light travel distance calculator

Speed of Light Calculator

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With this speed of light calculator, we aim to help you calculate the distance light can travel in a fixed time . As the speed of light is the fastest speed in the universe, it would be fascinating to know just how far it can travel in a short amount of time.

We have written this article to help you understand what the speed of light is , how fast the speed of light is , and how to calculate the speed of light . We will also demonstrate some examples to help you understand the computation of the speed of light.

What is the speed of light? How fast is the speed of light?

The speed of light is scientifically proven to be the universe's maximum speed. This means no matter how hard you try, you can never exceed this speed in this universe. Hence, there are also some theories on getting into another universe by breaking this limit. You can understand this more using our speed calculator and distance calculator .

So, how fast is the speed of light? The speed of light is 299,792,458 m/s in a vacuum. The speed of light in mph is 670,616,629 mph . With this speed, one can go around the globe more than 400,000 times in a minute!

One thing to note is that the speed of light slows down when it goes through different mediums. Light travels faster in air than in water, for instance. This phenomenon causes the refraction of light.

Now, let's look at how to calculate the speed of light.

How to calculate the speed of light?

As the speed of light is constant, calculating the speed of light usually falls on calculating the distance that light can travel in a certain time period. Hence, let's have a look at the following example:

• Source: Light
• Speed of light: 299,792,458 m/s
• Time traveled: 100 seconds

You can perform the calculation in three steps:

Determine the speed of light.

As mentioned, the speed of light is the fastest speed in the universe, and it is always a constant in a vacuum. Hence, the speed of light is 299,792,458 m/s .

Determine the time that the light has traveled.

The next step is to know how much time the light has traveled. Unlike looking at the speed of a sports car or a train, the speed of light is extremely fast, so the time interval that we look at is usually measured in seconds instead of minutes and hours. You can use our time lapse calculator to help you with this calculation.

For this example, the time that the light has traveled is 100 seconds .

Calculate the distance that the light has traveled.

The final step is to calculate the total distance that the light has traveled within the time . You can calculate this answer using the speed of light formula:

distance = speed of light × time

Thus, the distance that the light can travel in 100 seconds is 299,792,458 m/s × 100 seconds = 29,979,245,800 m

What is the speed of light in mph when it is in a vacuum?

The speed of light in a vacuum is 670,616,629 mph . This is equivalent to 299,792,458 m/s or 1,079,252,849 km/h. This is the fastest speed in the universe.

Is the speed of light always constant?

Yes , the speed of light is always constant for a given medium. The speed of light changes when going through different mediums. For example, light travels slower in water than in air.

How can I calculate the speed of light?

You can calculate the speed of light in three steps:

Determine the distance the light has traveled.

Apply the speed of light formula :

speed of light = distance / time

How far can the speed of light travel in 1 minute?

Light can travel 17,987,547,480 m in 1 minute . This means that light can travel around the earth more than 448 times in a minute.

Speed of light

The speed of light in the medium. In a vacuum, the speed of light is 299,792,458 m/s.

 Math and Physics Calculators

Please enter distance or time, the other value will be calculated. One year is counted as 31557600 seconds (365 1/4 days). Examples: the average distance of the moon from earth is 384400 kilometers. The light takes just under 1.3 seconds to get there. For one centimeter, light takes 3.3e-11 seconds. These are 0.000000000033 seconds (first digit ≠0 at the 11. decimal place).

The Distance Light Traveled calculator computes the distance ( D ) based on the duration of travel ( t ) and the Speed of Light .

INSTRUCTIONS:  Choose the preferred units and enter the following:

• ( t )   Duration of Travel
• ( v )  Travel Velocity (speed traveled with a default of 1 c,  the speed of light )

Distance Traveled (D):  The calculator returns the distance ( D ) in astronomical units or light years.  However, this can be automatically converted to other distance units via the pull-down menu.

The Math / Science

The formula for the distance that light has traveled  is:

• D is the distance that light has traveled
• t is the time it has traveled
• v is the speed of light .

Astronomy Distance Units

Astronomical Unit (au): Within our solar system, a common measure of distance is au , which stands for  astronomical units .  A single astronomical unit is the mean distance from the Sun's center to the center of the Earth . The following picture is NOT to scale.

Light Travel in Time:  Light is a primary observable when studying celestial bodies.  For this reason, the distance to these objects are measured in the amount of time it would take light to travel from there to the Earth.  We can say that an object is one light-year away, and that means that the object is at a distance where it took an entire year for light from the object to travel to Earth.  Since the  speed of light is 299,792,458.0 meters per second, one can compute the distance equal to a light year as follows:

1 light year = 299,792,458.0 (meters / second) x 31,536,000 (seconds / year) = 9,460,528,405,000,000 meters

The same exercise can be used for light traveling shorter periods of times, light seconds , light minutes , light hours and light days .  Since even these units are not enough when computing distances across the universe, there is also a light relative distance of  kilo-light years ( 1000 light years ), or the distance light travels in a thousand years!

Angle Shift Seen from Earth : Because the Earth goes around the Sun, our observation of distant objects such as stars results in an angular shift when observed at opposite sides of the elliptical orbit.  This shift is used as the basis of a unit knows as a parsec .  A parsec was traditionally defined as the distance where one astronomical unit subtends an angle of one arcsecond.  A parsec was redefined in 2015 to 648000/π  astronomical units .  Proxima Centauri, is the nearest star to the Sun and is approximately 1.3 parsecs (4.2 light-years) from the Sun. A mega-parsec  is a million parsecs .

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Speed of Light Calculator

Harness the power of light speed calculations with newtum.

Embark on a journey to comprehend the cosmos with our Speed of Light Calculator, meticulously crafted by Newtum. Unveil the mystery of light's velocity and quench your scientific curiosity.

Discover the Essence of This Revolutionary Computational Tool

The Speed of Light Calculator, a tool as luminous as its subject, allows you to effortlessly compute the universe's speed limit, the speed of light. With this calculator, the complex becomes accessible, turning the abstract into the attainable.

Unraveling the Formula Behind Light's Prowess

Gain insight into the pivotal formula that governs the speed of light, an essential constant in the realm of physics that shapes our understanding of time and space.

• Define the constants and variables involved in the calculation.
• Illustrate the relationship between light's velocity, frequency, and wavelength.
• Detail the application of the formula in different contexts and mediums.

Step-by-Step Mastery of the Speed of Light Calculator

Our Speed of Light Calculator is incredibly user-friendly. Just follow the simple steps below, and you'll swiftly calculate light's velocity with impeccable accuracy.

• Select the medium in which light is traveling.
• Input any necessary parameters such as frequency or wavelength.
• Click 'Calculate' to receive the speed of light in your chosen medium.

Why Choose Our Speed of Light Calculator: A Feature-Rich Experience

• User-Friendly Interface: Navigate with ease.
• Instant Results: Get calculations in a flash.
• Data Security: Your data never leaves your device.
• Accessibility Across Devices: Use it on any device with a web browser.
• No Installation Needed: Access directly online.
• Examples for Clarity: Understand with practical examples.
• Transparent Process: See how calculations are performed.
• Educational Resource: Learn more about the speed of light.
• Responsive Customer Support: We're here to help.
• Regular Updates: Benefit from the latest features and improvements.
• Privacy Assurance: No server-side data processing ensures your privacy.
• Efficient Age Retrieval: Quick and accurate.
• Language Accessibility: Available in multiple languages.
• Engaging and Informative Content: Enjoy the learning process.
• Fun and Interactive Learning: Engage with the tool interactively.
• Shareable Results: Easily share your findings.
• Responsive Design: Works seamlessly on various screen sizes.
• Educational Platform Integration: A valuable addition to educational resources.
• Comprehensive Documentation: Understand every aspect of the tool.

Exploring the Multifaceted Applications of the Speed of Light Calculator

• Analyze light's speed in different mediums for educational purposes.
• Use in scientific research to explore the properties of light.
• Assist in physics classroom demonstrations and experiments.
• Provide a reference for engineers working with light-based technologies.
• Offer an interactive learning experience for students and enthusiasts.

Demystifying the Speed of Light: Formula Examples in Action

Example 1: If the frequency (f) of light is 5 x 10 14 Hz and the wavelength (λ) is 600 nm, the speed (c) can be calculated using c = f * λ, resulting in 3 x 10 8 m/s.

Example 2: For light traveling through water with a refractive index (n) of 1.33, and using the known speed of light in a vacuum (c 0 ), the speed in water (v) is v = c 0 / n, giving us approximately 2.25 x 10 8 m/s.

Securing Your Data with Our Speed of Light Calculator

Concluding our exploration of the Speed of Light Calculator, we emphasize the unparalleled security of your data. As an entirely client-side tool, calculations are performed without data ever leaving your computer. This ensures that your inputs and results remain confidential, fostering a safe and private environment for your scientific inquiries. Harness the speed of light with the confidence that your data is safeguarded, reflecting Newtum's commitment to your privacy and the integrity of educational tools.

Frequently Asked Questions: Enlightening Your Path

• What is the Speed of Light Calculator? It's an online tool that calculates the speed of light based on various parameters.
• Can I use the calculator on my mobile device? Yes, it's designed to be accessible across all devices.
• Is it necessary to install any software to use the calculator? No, it operates directly in your web browser.
• How does the calculator ensure the privacy of my data? Calculations are processed locally, meaning your data never leaves your device.
• Does the calculator provide immediate results? Yes, it delivers instant calculations for an efficient experience.

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Light Speed Distance Calculator

Enter the total time of travel at light speed.

• Total Time of Travel at Light Speed s
• Calculate Reset
• Light Speed Distance m
• Where LS D is the Light Speed Distance (m)
• T is the total time of travel at light speed (s) 
• L S is the speed of light (299,792,458 m/s ≈ 3 x 10 8 m/s)

The speed of light in vacuum, commonly denoted c, is a universal physical constant that is exactly equal to 299,792,458 metres per second(≈ 3 x 10 8 m/s). According to the special theory of relativity, c is the upper limit for the speed at which conventional matter or energy can travel through space

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Light - Calculate Distance per Time

Stopwatch and calculator for calculating the distance light travels in a medium in a given time. The speed of light is constant and is almost 300000 kilometers per second in a vacuum. The light therefore covers a very large distance in a short time. It takes a little over a second to get to the moon and about 8 minutes from the sun to us.

The calculator can also be used without the stopwatch, simply enter time or distance and press Calculate.

Physics commonly uses SI units. Here is a calculator to convert units .

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How to Calculate Distance of Light

Distances of the Planets From the Sun in Light Years

Many people misunderstand what a “light-year” is. Although it sounds like a measure of time, because it includes year, it’s actually a distance. In a sense, it’s a distance expressed in terms of the speed of light, so you can also have other measures like a light-day or even a light-second. However, this is only part of the story, because distances on a cosmic scale are complicated by the expansion of the fabric of space-time. Calculating a light-year is easy, simply multiply the speed of light by the number of seconds in a year, but calculating cosmological distances isn’t quite so easy. The redshift of the object is the easiest thing to objectively define, but there are other concepts like the comoving distance that can be useful too.

TL;DR (Too Long; Didn't Read)

Find the distance in terms of light using the formula:

​ d ​ L = ​ ct ​

Where ​ c ​ is the speed of light, ​ d ​ L is the distance, and ​ t ​ is the time period. For a light year:

Light year = speed of light × number of seconds in a year

Cosmological distances can be found using a cosmological calculator and the redshift of the object in question.

How to Calculate a Light Year or Other Light Distance

Calculate a light year using the simple formula:

The speed of light is usually given the symbol ​ c ​, and if you multiply it by any length of time (​ t ​), you’ll get that “distance of light” (​ d ​ L ) out of the calculation. So you could write:

The speed of light is approximately 2.998 × 10 8 m/s, so a light-year is:

That calculation used 365.25 days per year to account for leap years. Similarly, a light-day is:

Cosmological Distances and Redshift

Distances over a cosmological scale are complicated because the whole fabric of space-time is constantly expanding. So, for example, if a light signal from a distant galaxy comes toward us, it moves at the speed of light and probably takes hundreds of millions of years to complete the journey. During that time, space itself has expanded, and so the distance is even farther than it would have been at the start of the journey. This makes it really hard to define what it really ​ means ​ to say something has traveled a certain distance through space. The “comoving” distance expands along with space, so it accounts for this problem, but it still isn’t right for all purposes.

The most objective measure of distance in space is the “redshift.” This measures how much the light wave has “stretched out” (moving it closer to the red end of the spectrum) because of the expansion of space during its journey. If it travels farther, it will have shifted the wavelength of the light more.

Redshift (​ z ​) is defined as:

Where ​ λ ​ is the symbol for wavelength and the “obs” and “rest” subscripts mean the wavelength you observe, and the wavelength in the reference frame where it was emitted, respectively. You can find the wavelength when it was emitted based on standard values obtained in a lab because different substances absorb and emit light in specific parts of the spectrum.

Finding the Cosmological Distance

Finding cosmological distances is pretty challenging. Although you can calculate it, the best approach is to use a cosmological calculator with some standard parameters already input. Enter the redshift of the object you want to find the distance to, using the parameters suggested by the calculator, and it will return many distance measures, including the comoving distance and the light travel time. You can multiply the light travel time (converted into seconds, as in the first section) by the speed of light to find the distance traveled by the light itself.

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• NASA: What is a Light Year and How is it Used?
• University of Florida: Distance Measures in Cosmology
• Swinburne University of Technology: Cosmological Redshift
• UCLA Division of Astronomy and Astrophysics: Ned Wright's Javascript Cosmology Calculator

About the Author

Lee Johnson is a freelance writer and science enthusiast, with a passion for distilling complex concepts into simple, digestible language. He's written about science for several websites including eHow UK and WiseGeek, mainly covering physics and astronomy. He was also a science blogger for Elements Behavioral Health's blog network for five years. He studied physics at the Open University and graduated in 2018.

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• Speed of light FAQs
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Bibliography

The speed of light traveling through a vacuum is exactly 299,792,458 meters (983,571,056 feet) per second. That's about 186,282 miles per second — a universal constant known in equations as "c," or light speed. 

According to physicist Albert Einstein 's theory of special relativity , on which much of modern physics is based, nothing in the universe can travel faster than light. The theory states that as matter approaches the speed of light, the matter's mass becomes infinite. That means the speed of light functions as a speed limit on the whole universe . The speed of light is so immutable that, according to the U.S. National Institute of Standards and Technology , it is used to define international standard measurements like the meter (and by extension, the mile, the foot and the inch). Through some crafty equations, it also helps define the kilogram and the temperature unit Kelvin .

But despite the speed of light's reputation as a universal constant, scientists and science fiction writers alike spend time contemplating faster-than-light travel. So far no one's been able to demonstrate a real warp drive, but that hasn't slowed our collective hurtle toward new stories, new inventions and new realms of physics.

Related: Special relativity holds up to a high-energy test

A l ight-year is the distance that light can travel in one year — about 6 trillion miles (10 trillion kilometers). It's one way that astronomers and physicists measure immense distances across our universe.

Light travels from the moon to our eyes in about 1 second, which means the moon is about 1 light-second away. Sunlight takes about 8 minutes to reach our eyes, so the sun is about 8 light minutes away. Light from Alpha Centauri , which is the nearest star system to our own, requires roughly 4.3 years to get here, so Alpha Centauri is 4.3 light-years away.

"To obtain an idea of the size of a light-year, take the circumference of the Earth (24,900 miles), lay it out in a straight line, multiply the length of the line by 7.5 (the corresponding distance is one light-second), then place 31.6 million similar lines end to end," NASA's Glenn Research Center says on its website . "The resulting distance is almost 6 trillion (6,000,000,000,000) miles!"

Stars and other objects beyond our solar system lie anywhere from a few light-years to a few billion light-years away. And everything astronomers "see" in the distant universe is literally history. When astronomers study objects that are far away, they are seeing light that shows the objects as they existed at the time that light left them. 

This principle allows astronomers to see the universe as it looked after the Big Bang , which took place about 13.8 billion years ago. Objects that are 10 billion light-years away from us appear to astronomers as they looked 10 billion years ago — relatively soon after the beginning of the universe — rather than how they appear today.

Related: Why the universe is all history

Speed of light FAQs answered by an expert

We asked Rob Zellem, exoplanet-hunter and staff scientist at NASA's Jet Propulsion Lab, a few frequently asked questions about the speed of light. 

Dr. Rob Zellem is a staff scientist at NASA's Jet Propulsion Laboratory, a federally funded research and development center operated by the California Institute of Technology. Rob is the project lead for Exoplanet Watch, a citizen science project to observe exoplanets, planets outside of our own solar system, with small telescopes. He is also the Science Calibration lead for the Nancy Grace Roman Space Telescope's Coronagraph Instrument, which will directly image exoplanets. 

What is faster than the speed of light?

Nothing! Light is a "universal speed limit" and, according to Einstein's theory of relativity, is the fastest speed in the universe: 300,000 kilometers per second (186,000 miles per second). 

Is the speed of light constant?

The speed of light is a universal constant in a vacuum, like the vacuum of space. However, light *can* slow down slightly when it passes through an absorbing medium, like water (225,000 kilometers per second = 140,000 miles per second) or glass (200,000 kilometers per second = 124,000 miles per second). 

Who discovered the speed of light?

One of the first measurements of the speed of light was by Rømer in 1676 by observing the moons of Jupiter . The speed of light was first measured to high precision in 1879 by the Michelson-Morley Experiment. 

How do we know the speed of light?

Rømer was able to measure the speed of light by observing eclipses of Jupiter's moon Io. When Jupiter was closer to Earth, Rømer noted that eclipses of Io occurred slightly earlier than when Jupiter was farther away. Rømer attributed this effect due the time it takes for light to travel over the longer distance when Jupiter was farther from the Earth. 

How did we learn the speed of light?

As early as the 5th century, Greek philosophers like Empedocles and Aristotle disagreed on the nature of light speed. Empedocles proposed that light, whatever it was made of, must travel and therefore, must have a rate of travel. Aristotle wrote a rebuttal of Empedocles' view in his own treatise, On Sense and the Sensible , arguing that light, unlike sound and smell, must be instantaneous. Aristotle was wrong, of course, but it would take hundreds of years for anyone to prove it. 

In the mid 1600s, the Italian astronomer Galileo Galilei stood two people on hills less than a mile apart. Each person held a shielded lantern. One uncovered his lantern; when the other person saw the flash, he uncovered his too. But Galileo's experimental distance wasn't far enough for his participants to record the speed of light. He could only conclude that light traveled at least 10 times faster than sound.

In the 1670s, Danish astronomer Ole Rømer tried to create a reliable timetable for sailors at sea, and according to NASA , accidentally came up with a new best estimate for the speed of light. To create an astronomical clock, he recorded the precise timing of the eclipses of Jupiter's moon , Io, from Earth . Over time, Rømer observed that Io's eclipses often differed from his calculations. He noticed that the eclipses appeared to lag the most when Jupiter and Earth were moving away from one another, showed up ahead of time when the planets were approaching and occurred on schedule when the planets were at their closest or farthest points. This observation demonstrated what we today know as the Doppler effect, the change in frequency of light or sound emitted by a moving object that in the astronomical world manifests as the so-called redshift , the shift towards "redder", longer wavelengths in objects speeding away from us. In a leap of intuition, Rømer determined that light was taking measurable time to travel from Io to Earth. 

Rømer used his observations to estimate the speed of light. Since the size of the solar system and Earth's orbit wasn't yet accurately known, argued a 1998 paper in the American Journal of Physics , he was a bit off. But at last, scientists had a number to work with. Rømer's calculation put the speed of light at about 124,000 miles per second (200,000 km/s).

In 1728, English physicist James Bradley based a new set of calculations on the change in the apparent position of stars caused by Earth's travels around the sun. He estimated the speed of light at 185,000 miles per second (301,000 km/s) — accurate to within about 1% of the real value, according to the American Physical Society .

Two new attempts in the mid-1800s brought the problem back to Earth. French physicist Hippolyte Fizeau set a beam of light on a rapidly rotating toothed wheel, with a mirror set up 5 miles (8 km) away to reflect it back to its source. Varying the speed of the wheel allowed Fizeau to calculate how long it took for the light to travel out of the hole, to the adjacent mirror, and back through the gap. Another French physicist, Leon Foucault, used a rotating mirror rather than a wheel to perform essentially the same experiment. The two independent methods each came within about 1,000 miles per second (1,609 km/s) of the speed of light.

Another scientist who tackled the speed of light mystery was Poland-born Albert A. Michelson, who grew up in California during the state's gold rush period, and honed his interest in physics while attending the U.S. Naval Academy, according to the University of Virginia . In 1879, he attempted to replicate Foucault's method of determining the speed of light, but Michelson increased the distance between mirrors and used extremely high-quality mirrors and lenses. Michelson's result of 186,355 miles per second (299,910 km/s) was accepted as the most accurate measurement of the speed of light for 40 years, until Michelson re-measured it himself. In his second round of experiments, Michelson flashed lights between two mountain tops with carefully measured distances to get a more precise estimate. And in his third attempt just before his death in 1931, according to the Smithsonian's Air and Space magazine, he built a mile-long depressurized tube of corrugated steel pipe. The pipe simulated a near-vacuum that would remove any effect of air on light speed for an even finer measurement, which in the end was just slightly lower than the accepted value of the speed of light today. 

Michelson also studied the nature of light itself, wrote astrophysicist Ethan Siegal in the Forbes science blog, Starts With a Bang . The best minds in physics at the time of Michelson's experiments were divided: Was light a wave or a particle? 

Michelson, along with his colleague Edward Morley, worked under the assumption that light moved as a wave, just like sound. And just as sound needs particles to move, Michelson and Morley and other physicists of the time reasoned, light must have some kind of medium to move through. This invisible, undetectable stuff was called the "luminiferous aether" (also known as "ether"). 

Though Michelson and Morley built a sophisticated interferometer (a very basic version of the instrument used today in LIGO facilities), Michelson could not find evidence of any kind of luminiferous aether whatsoever. Light, he determined, can and does travel through a vacuum.

"The experiment — and Michelson's body of work — was so revolutionary that he became the only person in history to have won a Nobel Prize for a very precise non-discovery of anything," Siegal wrote. "The experiment itself may have been a complete failure, but what we learned from it was a greater boon to humanity and our understanding of the universe than any success would have been!"

Special relativity and the speed of light

Einstein's theory of special relativity unified energy, matter and the speed of light in a famous equation: E = mc^2. The equation describes the relationship between mass and energy — small amounts of mass (m) contain, or are made up of, an inherently enormous amount of energy (E). (That's what makes nuclear bombs so powerful: They're converting mass into blasts of energy.) Because energy is equal to mass times the speed of light squared, the speed of light serves as a conversion factor, explaining exactly how much energy must be within matter. And because the speed of light is such a huge number, even small amounts of mass must equate to vast quantities of energy.

In order to accurately describe the universe, Einstein's elegant equation requires the speed of light to be an immutable constant. Einstein asserted that light moved through a vacuum, not any kind of luminiferous aether, and in such a way that it moved at the same speed no matter the speed of the observer. 

Think of it like this: Observers sitting on a train could look at a train moving along a parallel track and think of its relative movement to themselves as zero. But observers moving nearly the speed of light would still perceive light as moving away from them at more than 670 million mph. (That's because moving really, really fast is one of the only confirmed methods of time travel — time actually slows down for those observers, who will age slower and perceive fewer moments than an observer moving slowly.)

In other words, Einstein proposed that the speed of light doesn't vary with the time or place that you measure it, or how fast you yourself are moving. 

Therefore, objects with mass cannot ever reach the speed of light. If an object ever did reach the speed of light, its mass would become infinite. And as a result, the energy required to move the object would also become infinite: an impossibility.

That means if we base our understanding of physics on special relativity (which most modern physicists do), the speed of light is the immutable speed limit of our universe — the fastest that anything can travel. 

What goes faster than the speed of light?

Although the speed of light is often referred to as the universe's speed limit, the universe actually expands even faster. The universe expands at a little more than 42 miles (68 kilometers) per second for each megaparsec of distance from the observer, wrote astrophysicist Paul Sutter in a previous article for Space.com . (A megaparsec is 3.26 million light-years — a really long way.) 

In other words, a galaxy 1 megaparsec away appears to be traveling away from the Milky Way at a speed of 42 miles per second (68 km/s), while a galaxy two megaparsecs away recedes at nearly 86 miles per second (136 km/s), and so on. 

"At some point, at some obscene distance, the speed tips over the scales and exceeds the speed of light, all from the natural, regular expansion of space," Sutter explained. "It seems like it should be illegal, doesn't it?"

Special relativity provides an absolute speed limit within the universe, according to Sutter, but Einstein's 1915 theory regarding general relativity allows different behavior when the physics you're examining are no longer "local."

"A galaxy on the far side of the universe? That's the domain of general relativity, and general relativity says: Who cares! That galaxy can have any speed it wants, as long as it stays way far away, and not up next to your face," Sutter wrote. "Special relativity doesn't care about the speed — superluminal or otherwise — of a distant galaxy. And neither should you."

Does light ever slow down?

Light in a vacuum is generally held to travel at an absolute speed, but light traveling through any material can be slowed down. The amount that a material slows down light is called its refractive index. Light bends when coming into contact with particles, which results in a decrease in speed.

For example, light traveling through Earth's atmosphere moves almost as fast as light in a vacuum, slowing down by just three ten-thousandths of the speed of light. But light passing through a diamond slows to less than half its typical speed, PBS NOVA reported. Even so, it travels through the gem at over 277 million mph (almost 124,000 km/s) — enough to make a difference, but still incredibly fast.

Light can be trapped — and even stopped — inside ultra-cold clouds of atoms, according to a 2001 study published in the journal Nature . More recently, a 2018 study published in the journal Physical Review Letters proposed a new way to stop light in its tracks at "exceptional points," or places where two separate light emissions intersect and merge into one.

Researchers have also tried to slow down light even when it's traveling through a vacuum. A team of Scottish scientists successfully slowed down a single photon, or particle of light, even as it moved through a vacuum, as described in their 2015 study published in the journal Science . In their measurements, the difference between the slowed photon and a "regular" photon was just a few millionths of a meter, but it demonstrated that light in a vacuum can be slower than the official speed of light. 

Can we travel faster than light?

— Spaceship could fly faster than light

— Here's what the speed of light looks like in slow motion

— Why is the speed of light the way it is?

Science fiction loves the idea of "warp speed." Faster-than-light travel makes countless sci-fi franchises possible, condensing the vast expanses of space and letting characters pop back and forth between star systems with ease. 

But while faster-than-light travel isn't guaranteed impossible, we'd need to harness some pretty exotic physics to make it work. Luckily for sci-fi enthusiasts and theoretical physicists alike, there are lots of avenues to explore.

All we have to do is figure out how to not move ourselves — since special relativity would ensure we'd be long destroyed before we reached high enough speed — but instead, move the space around us. Easy, right? 

One proposed idea involves a spaceship that could fold a space-time bubble around itself. Sounds great, both in theory and in fiction.

"If Captain Kirk were constrained to move at the speed of our fastest rockets, it would take him a hundred thousand years just to get to the next star system," said Seth Shostak, an astronomer at the Search for Extraterrestrial Intelligence (SETI) Institute in Mountain View, California, in a 2010 interview with Space.com's sister site LiveScience . "So science fiction has long postulated a way to beat the speed of light barrier so the story can move a little more quickly."

Without faster-than-light travel, any "Star Trek" (or "Star War," for that matter) would be impossible. If humanity is ever to reach the farthest — and constantly expanding — corners of our universe, it will be up to future physicists to boldly go where no one has gone before.

Additional resources

For more on the speed of light, check out this fun tool from Academo that lets you visualize how fast light can travel from any place on Earth to any other. If you’re more interested in other important numbers, get familiar with the universal constants that define standard systems of measurement around the world with the National Institute of Standards and Technology . And if you’d like more on the history of the speed of light, check out the book " Lightspeed: The Ghostly Aether and the Race to Measure the Speed of Light " (Oxford, 2019) by John C. H. Spence.

Aristotle. “On Sense and the Sensible.” The Internet Classics Archive, 350AD. http://classics.mit.edu/Aristotle/sense.2.2.html .

D’Alto, Nick. “The Pipeline That Measured the Speed of Light.” Smithsonian Magazine, January 2017. https://www.smithsonianmag.com/air-space-magazine/18_fm2017-oo-180961669/ .

Fowler, Michael. “Speed of Light.” Modern Physics. University of Virginia. Accessed January 13, 2022. https://galileo.phys.virginia.edu/classes/252/spedlite.html#Albert%20Abraham%20Michelson .

Giovannini, Daniel, Jacquiline Romero, Václav Potoček, Gergely Ferenczi, Fiona Speirits, Stephen M. Barnett, Daniele Faccio, and Miles J. Padgett. “Spatially Structured Photons That Travel in Free Space Slower than the Speed of Light.” Science, February 20, 2015. https://www.science.org/doi/abs/10.1126/science.aaa3035 .

Goldzak, Tamar, Alexei A. Mailybaev, and Nimrod Moiseyev. “Light Stops at Exceptional Points.” Physical Review Letters 120, no. 1 (January 3, 2018): 013901. https://doi.org/10.1103/PhysRevLett.120.013901 . 

Hazen, Robert. “What Makes Diamond Sparkle?” PBS NOVA, January 31, 2000. https://www.pbs.org/wgbh/nova/article/diamond-science/ . 

“How Long Is a Light-Year?” Glenn Learning Technologies Project, May 13, 2021. https://www.grc.nasa.gov/www/k-12/Numbers/Math/Mathematical_Thinking/how_long_is_a_light_year.htm . 

American Physical Society News. “July 1849: Fizeau Publishes Results of Speed of Light Experiment,” July 2010. http://www.aps.org/publications/apsnews/201007/physicshistory.cfm . 

Liu, Chien, Zachary Dutton, Cyrus H. Behroozi, and Lene Vestergaard Hau. “Observation of Coherent Optical Information Storage in an Atomic Medium Using Halted Light Pulses.” Nature 409, no. 6819 (January 2001): 490–93. https://doi.org/10.1038/35054017 . 

NIST. “Meet the Constants.” October 12, 2018. https://www.nist.gov/si-redefinition/meet-constants . 

Ouellette, Jennifer. “A Brief History of the Speed of Light.” PBS NOVA, February 27, 2015. https://www.pbs.org/wgbh/nova/article/brief-history-speed-light/ . 

Shea, James H. “Ole Ro/Mer, the Speed of Light, the Apparent Period of Io, the Doppler Effect, and the Dynamics of Earth and Jupiter.” American Journal of Physics 66, no. 7 (July 1, 1998): 561–69. https://doi.org/10.1119/1.19020 . 

Siegel, Ethan. “The Failed Experiment That Changed The World.” Forbes, April 21, 2017. https://www.forbes.com/sites/startswithabang/2017/04/21/the-failed-experiment-that-changed-the-world/ . 

Stern, David. “Rømer and the Speed of Light,” October 17, 2016. https://pwg.gsfc.nasa.gov/stargaze/Sun4Adop1.htm . 

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Vicky Stein is a science writer based in California. She has a bachelor's degree in ecology and evolutionary biology from Dartmouth College and a graduate certificate in science writing from the University of California, Santa Cruz (2018). Afterwards, she worked as a news assistant for PBS NewsHour, and now works as a freelancer covering anything from asteroids to zebras. Follow her most recent work (and most recent pictures of nudibranchs) on Twitter. 

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Light Speed Calculator + Online Solver With Free Steps

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What Is a Light Speed Calculator?

How does the light speed calculator work, application of light year.

The calculator outputs the numerical value of distance with appropriate units.

Light Speed Calculator is an online handy tool that is designed to determine the distance light covers in a specified time.

The concept of calculating distance is an elementary topic in the field of physics . When the numerical value for the speed of light was determined, the researchers focused to calculate the distance light covers.

This led to the discovery of numerous theories like Einstein’s famous equation $e=mc^{2}$ which states that mass and energy are interchangeable. Then the concept of the light-year describes how much light can travel in one year.

Also, the speed of light is used in many formulas like $c=f\lambda$. Therefore it’s important to determine the distance light covers. It is an easy method to calculate the distance as it is the product of speed and time(d=vt).

But in the era of modern technology, you don’t need to perform calculations by hand. You need a speedy calculator that can solve these distance problems for you. That’s why we offer an advanced calculator which is known as Light Speed Calculator .

It gives you the exact value of the distance traveled by the light in a few seconds. An interesting feature about this calculator is that it can accept time values in any unit like day, week or month, etc. It saves you from the hectic process of unit conversion too.

This calculator does not require any downloading and installation. You can get it in your browser at any time and place.

How To Use the Light Speed Calculator?

You can use the Light Speed Calculator by putting various values of time in the calculator to get the distance for each value. The operation is pretty straightforward as you need to enter only one element and just by clicking a button you can get the result.

There are two simple steps that you need to follow while using the calculator. The steps are as follows:

First of all, enter the amount of time in the input box. This can be in any unit like minutes, hours or days, weeks, etc.

Then simply press the Calculate tab to obtain the solution. It will display the value of distance with its unit(m/s).

This calculator works by finding the distance the light travels in the given time. The required distance is calculated when we insert the time into the calculator. This distance is calculated using the following formula:

Where s is the distance that light travels, c is the speed of light which is equal to 3.0 x $10^{8}$ m/s , and t is the time to cover the required distance.

The distance that light covers at different times are of great importance. Light can travel in space because of this property of light, these distances have applications in astronomy systems.

Since the galaxy is so huge, there is a need for some reference unit that describes the distances the light travels in space. Finally, they came up with the unit called a light-year.

A light-year is a distance that light travels in one year . This distance can be found by using the formula:

The speed of light is constant and the time of one year in seconds is given as:

1 year= 365*24*60*60

1 year= 31,536,000 s

Hence one light-year can be calculated as:

1 light year= 3.0 x $10^{8}$ m/s * 31,536,000 s

1 light year= 9.46 x $10^{15}$ m

The distance is not only confined to a year but with the same approach, the distance that light travels in one second are called One light-second, or the distance traveled in one minute is called One light-minute can also be calculated.

This unit of distance makes it feasible to measure the distance of the earth to the sun or other planets. These distances, when measured in kilometers or miles, give very large numbers which are cumbersome to use in the calculations.

However, these distances can be measured in light-years or light minutes. For instance, the earth is about eight light minutes from the sun and Mars is about 12.7 light minutes away from the sun.

Light-year is a unit of distance and it has many applications. This unit helps to determine the age of the celestial bodies. Suppose that a star is one million light-years away. The light from this star is traveled at the speed of light.

Hence it took one million years to reach the light of the star to us. We can conclude that this star’s light was lightened up million years ago. So the star we see today is not in its actual shape but it is in that shape in which it looks a million years ago.

Similarly, the distance of our earth from the sun is about eight light minutes. The rays from the sun that we see in the daytime are generated eight light minutes ago. But we can see these rays after eight light minutes.

Solved Examples

Let’s discuss some problems solved by Light Speed Calculator to understand how it works.

A college student while working on the celestial bodies is asked to find the distance that light travel from earth to that celestial body in five years.

The distance can easily be found by inserting the given time in the light speed calculator.

Distance light travels in five years:

3.0 x $10^{8}$ m/s * 157,680,000 s

4.7304 x $10^{16}$ m

Determine the distance that light covers in 12 hours. Use the calculator to find the exact value of distance.

The solution using the calculator is given below:

The distance light covers in twelve hours:

3.0 x $10^{8}$ m/s * 43200  s

1.296 x $10^{13}$ m

An astrologist working on a mega project needs to know how much distance light can travel within 3 weeks?

The distance that light traveled in 3 weeks is given by the calculator as follows:

The distance light travels in three weeks:

3.0 x $10^{8}$ m/s * 1.814 x $10^{6}$  s

5.442 x $10^{14}$  m

Valence Electron Calculator < Math Calculators List > Bps Calculator

CalculatorGem

Light Speed Distance Calculator

In the vast expanse of the cosmos, where distances are measured in light-years and the scale of the universe seems incomprehensible, tools like the Light Speed Distance Calculator become indispensable for astronomers and enthusiasts alike. Imagine being able to fathom the distance to a star, a galaxy, or even a distant quasar within seconds. This blog post delves into the intricacies of this remarkable tool and how it revolutionizes our understanding of the universe.

Understanding Light Speed

Before delving into the calculator itself, it’s crucial to grasp the concept of light speed. Light travels at a mind-boggling speed of approximately 299,792 kilometers per second (or about 186,282 miles per second) in a vacuum. This speed is the cosmic speed limit, beyond which nothing can surpass. It forms the foundation of our understanding of distances in space.

The Light Speed Distance Calculator: Unraveling the Universe

The Light Speed Distance Calculator harnesses the fundamental constant of the universe, the speed of light, to determine the distance between celestial objects and us. Its functionality is elegantly simple yet immensely powerful. Users input the time it takes for light to travel from the celestial object to Earth, and the calculator swiftly computes the corresponding distance.

Practical Applications

Stellar distances.

One of the most common applications of the Light Speed Distance Calculator is measuring the distance to stars. Astronomers observe a star’s brightness fluctuations over time, known as its luminosity, and then use this data to calculate the time it takes for light to reach Earth from that star. With this time value, the calculator can unveil the star’s distance from us, offering insights into its nature and characteristics.

Cosmic Proximity

Beyond stars, the Light Speed Distance Calculator extends its reach to galaxies, nebulae, and even distant quasars. By analyzing the light emitted by these cosmic entities, astronomers can discern their distance from Earth, painting a clearer picture of our cosmic neighborhood.

Limitations and Considerations

While the Light Speed Distance Calculator is a remarkable tool, it does have its limitations. It assumes that light travels in a vacuum at a constant speed, neglecting factors such as gravitational lensing or the expansion of the universe, which can subtly distort measurements over vast distances. Additionally, the accuracy of distance measurements decreases as we peer deeper into the cosmos due to the inherent limitations of our observational tools.

In the grand tapestry of the cosmos, the Light Speed Distance Calculator serves as a guiding light, illuminating the vast expanses of space and unraveling the mysteries of the universe. Its ability to effortlessly compute distances to celestial objects revolutionizes our understanding of the cosmos, allowing us to navigate the heavens with unprecedented precision and clarity. As we continue to explore the universe, tools like these will undoubtedly remain invaluable companions in our cosmic journey.

Space Travel Calculator

Prepare for launch and fasten your seatbelts because we’re about to take a galactic joyride into the cosmos! 🚀✨

Formula for Space Travel:

Now, let’s boldly go where no calculator has gone before!

Table of Contents

Categories of Space Travel

From short interplanetary jaunts to epic journeys across the universe, space travel can be categorized into mind-boggling types:

Examples of Space Travel Calculations

Hold onto your space helmets as we calculate some whimsical space journeys:

Different Methods of Calculation

Space travel calculations can be as diverse as the cosmos itself, each with its quirks and peculiarities:

Evolution of Space Travel Calculation

The history of space travel calculations is a journey in itself:

Limitations of Accuracy

Even in the vastness of space, accuracy has its limits:

• Complexity: Space travel equations can involve complex math and relativistic principles.
• Specific Scenarios: Some methods are limited to specific scenarios, like near-light-speed travel.
• Theoretical Speculation: Hyperspace theory remains speculative and unproven.

Alternative Methods for Measurement

When it comes to space travel, alternative methods are often found in the realm of science fiction:

FAQs on Space Travel Calculator

• Can space travel be faster than the speed of light? According to current physics, traveling at or faster than the speed of light is impossible.
• What is time dilation in space travel? Time dilation is the effect where time passes differently for travelers moving at high speeds or in strong gravitational fields.
• Are wormholes real and can we use them for space travel? Wormholes are theoretical, and their existence is unproven. They remain a concept in the realm of science fiction.
• How does space travel affect time? Traveling at high speeds, as described by special relativity, can cause time dilation, where time passes more slowly for the traveler than for those at rest.
• What is the concept of hyperspace travel? Hyperspace is a theoretical concept where ships can travel faster than light by entering another dimension or space.
• Is it possible to travel back in time through space travel? Current scientific understanding suggests that traveling backward in time is highly unlikely and remains a subject of science fiction.
• How far can humans travel in space today? Human space travel is primarily limited to our solar system, with missions to Mars and beyond in planning stages.
• What is the closest star to Earth? The closest star to Earth is the Sun, which is part of our solar system. The closest star system is Alpha Centauri.
• How do scientists calculate travel time to other planets? Scientists use the principles of physics, including special relativity and rocket science, to calculate travel time to other planets.
• What is the ultimate goal of space travel? The ultimate goal of space travel is to explore, understand, and potentially colonize other planets, and to expand humanity’s presence in the universe.

Resources for Further Research

Explore more about space travel through these reputable government and educational resources:

• NASA’s Official Space Travel Page : Discover NASA’s missions, research, and the latest in space travel.
• Space.com – Space News : Stay updated with the latest news, articles, and information on space exploration.
• ESA – European Space Agency : Explore Europe’s contribution to space science, technology, and exploration.
• Caltech – Jet Propulsion Laboratory : Learn about space missions, robotics, and planetary exploration.

Chapter 15: Galaxies

Chapter 1 how science works.

• The Scientific Method
• Measurements
• Units and the Metric System
• Measurement Errors
• Mass, Length, and Time
• Observations and Uncertainty
• Precision and Significant Figures
• Errors and Statistics
• Scientific Notation
• Ways of Representing Data
• Mathematics
• Testing a Hypothesis
• Case Study of Life on Mars
• Systems of Knowledge
• The Culture of Science
• Computer Simulations
• Modern Scientific Research
• The Scope of Astronomy
• Astronomy as a Science
• A Scale Model of Space
• A Scale Model of Time

Chapter 2 Early Astronomy

• The Night Sky
• Motions in the Sky
• Constellations and Seasons
• Cause of the Seasons
• The Magnitude System
• Angular Size and Linear Size
• Phases of the Moon
• Dividing Time
• Solar and Lunar Calendars
• History of Astronomy
• Ancient Observatories
• Counting and Measurement
• Greek Astronomy
• Aristotle and Geocentric Cosmology
• Aristarchus and Heliocentric Cosmology
• The Dark Ages
• Arab Astronomy
• Indian Astronomy
• Chinese Astronomy
• Mayan Astronomy

Chapter 3 The Copernican Revolution

• Ptolemy and the Geocentric Model
• The Renaissance
• Copernicus and the Heliocentric Model
• Tycho Brahe
• Johannes Kepler
• Elliptical Orbits
• Kepler's Laws
• Galileo Galilei
• The Trial of Galileo
• Isaac Newton
• Newton's Law of Gravity
• The Plurality of Worlds
• The Birth of Modern Science
• Layout of the Solar System
• Scale of the Solar System
• The Idea of Space Exploration
• History of Space Exploration
• Moon Landings
• International Space Station
• Manned versus Robotic Missions
• Commercial Space Flight
• Future of Space Exploration
• Living in Space
• Moon, Mars, and Beyond
• Societies in Space

Chapter 4 Matter and Energy in the Universe

• Matter and Energy
• Rutherford and Atomic Structure
• Early Greek Physics
• Dalton and Atoms
• The Periodic Table
• Structure of the Atom
• Heat and Temperature
• Potential and Kinetic Energy
• Conservation of Energy
• Velocity of Gas Particles
• States of Matter
• Thermodynamics
• Laws of Thermodynamics
• Heat Transfer
• Thermal Radiation
• Radiation from Planets and Stars
• Internal Heat in Planets and Stars
• Periodic Processes
• Random Processes

Chapter 5 The Earth-Moon System

• Earth and Moon
• Early Estimates of Earth's Age
• How the Earth Cooled
• Ages Using Radioactivity
• Radioactive Half-Life
• Ages of the Earth and Moon
• Geological Activity
• Internal Structure of the Earth and Moon
• Basic Rock Types
• Layers of the Earth and Moon
• Origin of Water on Earth
• The Evolving Earth
• Plate Tectonics
• Geological Processes
• Impact Craters
• The Geological Timescale
• Mass Extinctions
• Evolution and the Cosmic Environment
• Earth's Atmosphere and Oceans
• Weather Circulation
• Environmental Change on Earth
• The Earth-Moon System
• Geological History of the Moon
• Tidal Forces
• Effects of Tidal Forces
• Historical Studies of the Moon
• Lunar Surface
• Ice on the Moon
• Origin of the Moon
• Humans on the Moon

Chapter 6 The Terrestrial Planets

• Studying Other Planets
• The Planets
• The Terrestrial Planets
• Mercury's Orbit
• Mercury's Surface
• Volcanism on Venus
• Venus and the Greenhouse Effect
• Tectonics on Venus
• Exploring Venus
• Mars in Myth and Legend
• Early Studies of Mars
• Mars Close-Up
• Modern Views of Mars
• Missions to Mars
• Geology of Mars
• Water on Mars
• Polar Caps of Mars
• Climate Change on Mars
• Terraforming Mars
• Life on Mars
• The Moons of Mars
• Martian Meteorites
• Comparative Planetology
• Incidence of Craters
• Counting Craters
• Counting Statistics
• Internal Heat and Geological Activity
• Magnetic Fields of the Terrestrial Planets
• Mountains and Rifts
• Radar Studies of Planetary Surfaces
• Laser Ranging and Altimetry
• Gravity and Atmospheres
• Normal Atmospheric Composition
• The Significance of Oxygen

Chapter 7 The Giant Planets and Their Moons

• The Gas Giant Planets
• Atmospheres of the Gas Giant Planets
• Clouds and Weather on Gas Giant Planets
• Internal Structure of the Gas Giant Planets
• Thermal Radiation from Gas Giant Planets
• Life on Gas Giant Planets?
• Why Giant Planets are Giant
• Ring Systems of the Giant Planets
• Structure Within Ring Systems
• The Origin of Ring Particles
• The Roche Limit
• Resonance and Harmonics
• Tidal Forces in the Solar System
• Moons of Gas Giant Planets
• Geology of Large Moons
• The Voyager Missions
• Jupiter's Galilean Moons
• Jupiter's Ganymede
• Jupiter's Europa
• Jupiter's Callisto
• Jupiter's Io
• Volcanoes on Io
• Cassini Mission to Saturn
• Saturn's Titan
• Saturn's Enceladus
• Discovery of Uranus and Neptune
• Uranus' Miranda
• Neptune's Triton
• The Discovery of Pluto
• Pluto as a Dwarf Planet
• Dwarf Planets

Chapter 8 Interplanetary Bodies

• Interplanetary Bodies
• Early Observations of Comets
• Structure of the Comet Nucleus
• Comet Chemistry
• Oort Cloud and Kuiper Belt
• Kuiper Belt
• Comet Orbits
• Life Story of Comets
• The Largest Kuiper Belt Objects
• Meteors and Meteor Showers
• Gravitational Perturbations
• Surveys for Earth Crossing Asteroids
• Asteroid Shapes
• Composition of Asteroids
• Introduction to Meteorites
• Origin of Meteorites
• Types of Meteorites
• The Tunguska Event
• The Threat from Space
• Probability and Impacts
• Impact on Jupiter
• Interplanetary Opportunity

Chapter 9 Planet Formation and Exoplanets

• Formation of the Solar System
• Early History of the Solar System
• Conservation of Angular Momentum
• Angular Momentum in a Collapsing Cloud
• Helmholtz Contraction
• Safronov and Planet Formation
• Collapse of the Solar Nebula
• Why the Solar System Collapsed
• From Planetesimals to Planets
• Accretion and Solar System Bodies
• Differentiation
• Planetary Magnetic Fields
• The Origin of Satellites
• Solar System Debris and Formation
• Gradual Evolution and a Few Catastrophies
• Chaos and Determinism
• Extrasolar Planets
• Discoveries of Exoplanets
• Doppler Detection of Exoplanets
• Transit Detection of Exoplanets
• The Kepler Mission
• Direct Detection of Exoplanets
• Properties of Exoplanets
• Implications of Exoplanet Surveys
• Future Detection of Exoplanets

Chapter 10 Detecting Radiation from Space

• Observing the Universe
• Radiation and the Universe
• The Nature of Light
• The Electromagnetic Spectrum
• Properties of Waves
• Waves and Particles
• How Radiation Travels
• Properties of Electromagnetic Radiation
• The Doppler Effect
• Invisible Radiation
• Thermal Spectra
• The Quantum Theory
• The Uncertainty Principle
• Spectral Lines
• Emission Lines and Bands
• Absorption and Emission Spectra
• Kirchoff's Laws
• Astronomical Detection of Radiation
• The Telescope
• Optical Telescopes
• Optical Detectors
• Adaptive Optics
• Image Processing
• Digital Information
• Radio Telescopes
• Telescopes in Space
• Hubble Space Telescope
• Interferometry
• Collecting Area and Resolution
• Frontier Observatories

Chapter 11 Our Sun: The Nearest Star

• The Nearest Star
• Properties of the Sun
• Kelvin and the Sun's Age
• The Sun's Composition
• Energy From Atomic Nuclei
• Mass-Energy Conversion
• Examples of Mass-Energy Conversion
• Energy From Nuclear Fission
• Energy From Nuclear Fusion
• Nuclear Reactions in the Sun
• The Sun's Interior
• Energy Flow in the Sun
• Collisions and Opacity
• Solar Neutrinos
• Solar Oscillations
• The Sun's Atmosphere
• Solar Chromosphere and Corona
• The Solar Cycle
• The Solar Wind
• Effects of the Sun on the Earth
• Cosmic Energy Sources

Chapter 12 Properties of Stars

• Star Properties
• The Distance to Stars
• Apparent Brightness
• Absolute Brightness
• Measuring Star Distances
• Stellar Parallax
• Spectra of Stars
• Spectral Classification
• Temperature and Spectral Class
• Stellar Composition
• Stellar Motion
• Stellar Luminosity
• The Size of Stars
• Stefan-Boltzmann Law
• Stellar Mass
• Hydrostatic Equilibrium
• Stellar Classification
• The Hertzsprung-Russell Diagram
• Volume and Brightness Selected Samples
• Stars of Different Sizes
• Understanding the Main Sequence
• Stellar Structure
• Stellar Evolution

Chapter 13 Star Birth and Death

• Star Birth and Death
• Understanding Star Birth and Death
• Cosmic Abundance of Elements
• Star Formation
• Molecular Clouds
• Young Stars
• T Tauri Stars
• Mass Limits for Stars
• Brown Dwarfs
• Young Star Clusters
• Cauldron of the Elements
• Main Sequence Stars
• Nuclear Reactions in Main Sequence Stars
• Main Sequence Lifetimes
• Evolved Stars
• Cycles of Star Life and Death
• The Creation of Heavy Elements
• Horizontal Branch and Asymptotic Giant Branch Stars
• Variable Stars
• Magnetic Stars
• Stellar Mass Loss
• White Dwarfs
• Seeing the Death of a Star
• Supernova 1987A
• Neutron Stars and Pulsars
• Special Theory of Relativity
• General Theory of Relativity
• Black Holes
• Properties of Black Holes

Chapter 14 The Milky Way

• The Distribution of Stars in Space
• Stellar Companions
• Binary Star Systems
• Binary and Multiple Stars
• Mass Transfer in Binaries
• Binaries and Stellar Mass
• Nova and Supernova
• Exotic Binary Systems
• Gamma Ray Bursts
• How Multiple Stars Form
• Environments of Stars
• The Interstellar Medium
• Effects of Interstellar Material on Starlight
• Structure of the Interstellar Medium
• Dust Extinction and Reddening
• Groups of Stars
• Open Star Clusters
• Globular Star Clusters
• Distances to Groups of Stars
• Ages of Groups of Stars
• Layout of the Milky Way
• William Herschel
• Isotropy and Anisotropy
• Mapping the Milky Way

Chapter 15 Galaxies

• The Milky Way Galaxy
• Mapping the Galaxy Disk
• Spiral Structure in Galaxies
• Mass of the Milky Way
• Dark Matter in the Milky Way
• Galaxy Mass
• The Galactic Center
• Black Hole in the Galactic Center
• Stellar Populations
• Formation of the Milky Way
• The Shapley-Curtis Debate
• Edwin Hubble
• Distances to Galaxies
• Classifying Galaxies
• Spiral Galaxies
• Elliptical Galaxies
• Lenticular Galaxies
• Dwarf and Irregular Galaxies
• Overview of Galaxy Structures
• The Local Group

Light Travel Time

• Galaxy Size and Luminosity
• Mass to Light Ratios
• Dark Matter in Galaxies
• Gravity of Many Bodies
• Galaxy Evolution
• Galaxy Interactions
• Galaxy Formation

Chapter 16 The Expanding Universe

• Galaxy Redshifts
• The Expanding Universe
• Cosmological Redshifts
• The Hubble Relation
• Relating Redshift and Distance
• Galaxy Distance Indicators
• Size and Age of the Universe
• The Hubble Constant
• Large Scale Structure
• Galaxy Clustering
• Clusters of Galaxies
• Overview of Large Scale Structure
• Dark Matter on the Largest Scales
• The Most Distant Galaxies
• Black Holes in Nearby Galaxies
• Active Galaxies
• Radio Galaxies
• The Discovery of Quasars
• Types of Gravitational Lensing
• Properties of Quasars
• The Quasar Power Source
• Quasars as Probes of the Universe
• Star Formation History of the Universe
• Expansion History of the Universe

Chapter 17 Cosmology

• Early Cosmologies
• Relativity and Cosmology
• The Big Bang Model
• The Cosmological Principle
• Universal Expansion
• Cosmic Nucleosynthesis
• Cosmic Microwave Background Radiation
• Discovery of the Microwave Background Radiation
• Measuring Space Curvature
• Cosmic Evolution
• Evolution of Structure
• Mean Cosmic Density
• Critical Density
• Dark Matter and Dark Energy
• Age of the Universe
• Precision Cosmology
• The Future of the Contents of the Universe
• Fate of the Universe
• Alternatives to the Big Bang Model
• Particles and Radiation
• The Very Early Universe
• Mass and Energy in the Early Universe
• Matter and Antimatter
• The Forces of Nature
• Fine-Tuning in Cosmology
• The Anthropic Principle in Cosmology
• String Theory and Cosmology
• The Multiverse
• The Limits of Knowledge

Chapter 18 Life On Earth

• Nature of Life
• Chemistry of Life
• Molecules of Life
• The Origin of Life on Earth
• Origin of Complex Molecules
• Miller-Urey Experiment
• Pre-RNA World
• From Molecules to Cells
• Extremophiles
• Thermophiles
• Psychrophiles
• Acidophiles
• Alkaliphiles
• Radiation Resistant Biology
• Importance of Water for Life
• Hydrothermal Systems
• Silicon Versus Carbon
• DNA and Heredity
• Life as Digital Information
• Synthetic Biology
• Life in a Computer
• Natural Selection
• Tree Of Life
• Evolution and Intelligence
• Culture and Technology
• The Gaia Hypothesis
• Life and the Cosmic Environment

Chapter 19 Life in the Universe

• Life in the Universe
• Astrobiology
• Life Beyond Earth
• Sites for Life
• Complex Molecules in Space
• Life in the Solar System
• Lowell and Canals on Mars
• Implications of Life on Mars
• Extreme Environments in the Solar System
• Rare Earth Hypothesis
• Are We Alone?
• Unidentified Flying Objects or UFOs
• The Search for Extraterrestrial Intelligence
• The Drake Equation
• The History of SETI
• Recent SETI Projects
• Recognizing a Message
• The Best Way to Communicate
• The Fermi Question
• The Anthropic Principle
• Where Are They?

In the everyday world, as perceived by the human senses, light seems to travel instantaneously from one place to another. In fact, the speed of light is not infinite, and light doesn't instantly jump from your ceiling light to your desk and then to your eye. We perceive light as moving instantly because its actual velocity is almost unimaginably high; light travels at 300,000 km/s, denoted c. Using the equation Rate × Time = Distance, you can divide any distance by this number to figure out the time it would take light to cross that distance. In this way, we can see that light takes 1.5 × 10 8 / 3 × 10 5 = 500 seconds to reach Earth from the Sun, or just over 8 minutes. It takes light about 40 times longer ( Pluto at a distance of 39.4 A.U.) to leave the Solar System or about 5 hours.

The speed of light is a built-in quality of our universe . All evidence to date indicates that light has always traveled at this speed, that the speed is exact, and that the same speed is observed for all observers. The vast size of the universe, coupled with the finite (albeit large) speed of light, means that as we look out in space, we look back in time. Distant light is old light.

The 5 hours it takes light to travel across our Solar System may seem like a short period to cross such a large distance, but we have to think about scale. While distances within the Solar System are large to us, they are dwarfed by the distances between the stars. Considering larger regions of the Milky Way, a natural distance unit is the distance light travels in one year. This is called a light year. We can easily calculate the size of this unit by remembering that distance has the units of velocity times time. So:

D ly = vt = c x 1 year = 3 × 10 5 x (3600 × 24 × 365) = 9.5 × 10 12 km

A light year is the typical distance between stars in the neighborhood of the Sun. It is nearly 10 trillion kilometers or 6 trillion miles! The fundamental unit of distance defined by geometry is the 13 km; defined as the distance corresponding to a parallax of 1 second of arc.">parsec , equal to 3.1 × 10 13 km. This is described in more detail in the article on parallax . Geometrically, one parsec is the height of a right triangle with an angle of 1 arcsec describing its apex , and a distance of 1 AU describing its base. The units are related by a small numerical constant D ly = 3.26 D pc . So to roughly convert from parsecs to light years, multiply by 3.3.

The following list gives the distance to various points within the Milky Way and beyond, both in terms of parsecs and the light travel time in years (which is also the distance in light years or 3.3 times the distance in parsecs). To fully appreciate how isolated we are in space, remember that light is the fastest thing we know of. The fastest spacecraft can not reach 1% of the speed of light. So you would have to multiply the numbers on the right-hand side of the table by at least 100 to estimate how long it would take to send a probe through the Milky Way and into the Local Group with current technology.

• Nearest star (α Centauri) - 1.3 pc, 4.2 years • Sirius - 2.7 pc, 8.8 years • Vega - 8.1 pc, 26 years • Hyades cluster - 42 pc, 134 years • Pleiades cluster - 125 pc, 411 years • Orion nebula - 460 pc, 1500 years • Nearest spiral arm - 1200 pc, 3900 years • Center of the 8 to 10 13 solar masses.">galaxy - 8500 pc, 29,000 years • Far edge of the galaxy - 24,000 pc, 78,000 years • Large Magellanic Cloud - 50,000 pc, 163,000 years • Andromeda galaxy (M31) - 670,000 pc, 2.2 million years

What does Andromeda look like now? Nobody knows. Since nothing travels faster than light (and this applies to all the colors of light across the electromagnetic spectrum ), there is no quicker way to send information from one place to another. We are stuck with collecting and measuring "old" light. While this seems like a limitation, scientists actually find that it turns out that light travel time is a wonderful tool. By looking further out in space we look further back in time. In this way, astronomers get to explore the earlier stages of the universe seeing firsthand (with a delay) what the early universe looked like.

Distance Calculator

Quick links, distance calculator.

Travelmath provides an online travel distance calculator to help you measure both flying distances and driving distances. You can then compare the two results to see the difference. Flight distance is computed from a GPS-accurate great circle formula, which gives you the straight line distance "as the crow flies". Driving distance by car is determined from the actual turn-by-turn driving directions. If you want to split the distance with a friend, you can use the halfway point calculator to find the best place to meet. For a long distance trip, you can plan a road trip with stops . Or browse the mileage charts for any state or country.

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Speed, Distance & Time Calculator

Use this speed calculator to easily calculate the average speed, distance travelled and the trip duration of a vehicle: car, bus, train, bike, motorcycle, plane etc. Works with miles, feet, kilometers, meters, etc..

Related calculators

• Speed, Distance & Time Calculation
• Average Speed formula
• Distance formula
• Duration (Time) formula
• How to calculate the average speed of a car?

    Speed, Distance & Time Calculation

In order to use the above speed, distance & time calculator, or do such math on your own, you will need to know two out of three metrics: speed, distance, time. You will need to convert the metrics to the same time and distance units, e.g. miles, kilometers, meters, yards, feet, and hours, minutes or seconds. For example, if you have speed in mph (miles per hour), time should also be in hours. If you have distance in kilometers, then speed should also be in km/h (kilometers per hour).

The unit of the result will depend on the units you input, but our speed calculator will conveniently display additional units where appropriate.

    Average Speed formula

The formula for average speed, also called average velocity in physics and engineering, is:

where v is the velocity, d is the distance, and t is the time, so you can read it as Speed = Distance / Time . As noted above, make sure you convert the units appropriately first, or use our speed calculator which does that automatically. The resulting unit will depend on the units for both time and distance, so if your input was in miles and hours, the speed will be in mph. If it was in meters and seconds, it will be in m/s (meters per second).

Example: If you took a plane from New York to Los Angeles and the flight was 5 hours of air time, what was the speed of the plane, given that the flight path was 2450 miles? The answer is 2450 / 5 = 490 mph (miles per hour) average speed. If you want the result in km/h, you can convert from miles to km to get 788.58 km/h.

    Distance formula

The formula for distance, if you know time (duration) and the average speed, is:

Example: If a truck travelled at an average speed of 80 km per hour for 4 hours, how many miles did it cover in that time? To find the miles covered, first, calculate 80 * 4 = 320 km, then convert km to miles by dividing by 1.6093 or by using our km to miles converter to get the answer: 198.84 miles.

    Duration (Time) formula

The time, or more precisely, the duration of the trip, can be calculated knowing the distance and the average speed using the formula:

where d is the distance travelled, v is the speed (velocity) and t is the time, so you can read it as Time = Distance / Speed . Make sure you convert the units so both their distance and time components match, or use our trip duration calculator above which will handle conversions automatically. For example, if you have distance in miles and speed in km/h, you will need to convert speed to mph or distance to kilometers. The time unit of the result will match the time unit of the speed measure, so if it is measured in something per hour, the result will be in hours. If it is measured in some unit per second, the result will be in seconds.

Example: If a train can travel 500 miles with an average speed of 50 miles per hour, how long it would take it to complete a 500-mile route? To find the answer, use the formula and substitute the values, resulting in 500 / 50 = 10 hours.

    How to calculate the average speed of a car?

Say you travelled a certain distance with a car or another vehicle and you want to calculate what its average speed was. The easiest way to do that would be by using the calculator above, but if you prefer, you can also do the math yourself. Either way, you need to know the distance to a satisfactory approximation, for which you can use a map (e.g. Google Maps) to measure the distance from point to point. Make sure you measure closely to the path you took, and not via a straight line, unless you travelled by air in which case that would be a good approximation. Of course, having a GPS reading of the distance would be more precise. Then you need to know the travel time. Make sure you subtract any rests or stops you made from the total trip duration.

If the total distance travelled was 500 miles and the time it took you was 5 hours, then your average speed was 500 / 5 = 100 miles per hour (mph). If the distance was 300 kilometers and it took you 5 hours to cover it, your speed was 300 / 5 = 60 km/h (kilometers per hour).

Cite this calculator & page

If you'd like to cite this online calculator resource and information as provided on the page, you can use the following citation: Georgiev G.Z., "Speed Distance Time Calculator" , [online] Available at: https://www.gigacalculator.com/calculators/speed-calculator.php URL [Accessed Date: 11 Apr, 2024].

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