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# What is a light year?

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A light year is a measure of distance, or the distance a particle of light will travel through a pure vacuum in one Earth year.

This distance is approximately 5.8785 x 1012 [5.87 trillion] miles, or 9.4605 x 1012 [9.46 trillion] kilometers.

In a vacuum, light travels at almost 300,000 kilometers per second (more than 186,000 miles every second) so in a minute it will travel 60 times this amount (as there are 60 seconds in a minute). In 1 hour (60 mins) it will travel 60 times this amount. In 1 day (24 hrs) it will travel 24 times this amount. In 1 year (365 days) it will travel 365 times this amount. This amount is equivalent to almost 9.4605284 × 1012 kilometers or six million, million miles.

The nearest star (Proxima Centauri) is 4 1/4 light years away or approx. 25 million, million miles. The galaxy is 100,000 light years across The known universe is over 13 billion light years across. If a star is 10,000 light years away, we are seeing it today as it was 10,000 years ago - as the light that started out then is only just reaching us now. Similarly, if there were aliens looking at us through a powerful telescope on a planet 4 light years away, then they would just today be seeing what happened here 4 years ago.

The measurement of a light year is useful in finding distances to very distant objects, and as we're assuming that there is a pure vacuum between here and there, we can then determine how long ago, in Earth years, that light originated from its source. It is entirely possible that some of the stars we see from Earth are simply no longer there! A light year is a unit of distance. It is the distance that light can travel in one year. In one year, light can travel about 10 trillion km. One light-year is equal to 9,500,000,000,000 kilometers.
A light year is the distance covered by light in one year travelling at 186,000 miles per second.
Basically, a light year is the distance light would travel in a year. (Though I've often wondered what calender is used to define the length of the year, and has an adjustment been made for a leap year?)
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# What is a light year used for?

A light year is a measure of distance and is the distance light travels in one year's time. The light year is used to describe the enormous distances between various objects i

# What is a light year and how does it look?

It's a distance , and it looks 5.879x10^12 miles long.

# What is a light year distance?

The distance that light travels in a vacuum in 1 year is 5.88 (often rounded up to 5.9) trillion miles (or 9.46 trillion kilometers). A light-year is a unit of length, equal

# What is a light year and where is it used?

A light year is a unit of length: the distance light travels in one year, equal to about 9.461 x 1015 meters. It's used in astronomy to describe objects that are far enough aw

# What is a light year for space?

The distance light travels in a year is called a light year. hese are usually used to measure long distances in space.

# What is a light year in space?

Distance covered by light in one year.

# What is a light year according to astronomers?

A light-year is the distance light can travel in one year. Light travels at 186,000 miles per second. Multiply that by 3600 seconds in an hour and then by 24 hours in a day an

# What is a light year and how it is defined?

  A light year is how far light can travel in one year and is 9.461×10^12 km or 9,461,000,000,000 km

# What is a light year and why is it used?

It is a distance measurement. It is the distance light travels in one year in a vacuum like space, about 5,878,630,000,000 miles.

# What is a light year for a child to understand?

Its a distance, not a time. Light travels about a foot in a  millionth of a second, in a year it goes about 6 trillion miles.

# What is a light year and what is it a measurement of?

Scientists measure the distances in space in light-years. A light-year is the distance light-travels in 365 days. A light year is about 5,880 billion miles. The closest star t

# What is a light year in the solar system?

A light year is the distance light travels in a year. The orbit of Pluto ... the major solar system body that's farthest from the sun ... measures about 0.00124 light-yea

# What is a light year and the length of a light year?

A light year is a measure of distance, not velocity. It is the distance light travels in one year's time in the vacuum of space. This equates to 5,865,696,000,000 miles. Thi
In Science

# What is a light year what is an astronomical unit?

A light year is a measure of time, particularly time in space. A light year is simply the distance light travels in a year if nothing were to stop it, or slow it down.

# What is a light year in km and in AU?

1 light year = 9,460,730,472,580.8 km or 63,239.7263 Astronomical Units (AU).

# What is a light year away?

One light year away is equal to: 9,461,000,000,000 kilometers 9,461,000,000,000,000 meters 5,879,000,000,000 miles

Leap year