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The big yellow covering depicts a light-year; the smaller sized yellow shell depicts a light-month. Read much more about this photo at Wikimedia Commons.

You are watching: How many miles is a lightyear

Objects in our universe are exceptionally far away. They’re so much away the kilometers or miles aren’t a helpful measure of their distance. So us speak of an are objects in terms of light-years, the distance light travels in a year. Irradiate is the fastest-moving stuff in ours universe. It travel at 186,000 miles per second (300,000 km/sec). And also thus a light-year is 5.88 trillion miles (9.46 trillion kilometers).

But stars and also nebulae – not to mention distant galaxies – room vastly farther 보다 one light-year away. And, if we try to to express a star’s street in miles or kilometers, us soon end up v impossibly vast numbers. However miles and kilometers room what many of us use to understand the street from one ar on planet to another. In the so late 20th century astronomer Robert Burnham, Jr. – writer of Burnham’s Celestial Handbook – devised one ingenious way to portray the distance of light-years in terms of miles and kilometers.

Keep reading, because that a method to recognize the vastness that the universe, using units of street we know and use every day.

Burnham began by relating the light-year come the expensive unit – the Earth-sun distance.

One astronomical unit, or AU, equals about 93 million mile (150 million km).

Another method of looking in ~ it: the astronomical unit is a bit more than 8 light-minutes in distance.

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A light beam take away 8 minutes to travel the 93 million mile (150 million km) native the sunlight to the Earth. Photo via Brews Ohare/ Wikimedia Commons.

A light-year, pictured as a mile

Robert Burnham i found it that, fairly by coincidence, the number of astronomical units in one light-year and also the number of inches in one mile are virtually the same.

For general reference, there space 63,000 expensive units in one light-year, and also 63,360 inches (160,000 cm) in one mile (1.6 km).

This exorbitant coincidence enables us to lug the light-year under to Earth. If we range the astronomical unit – the Earth-sun distance – in ~ one inch, then the light-year ~ above this range represents one mile (1.6 km).

The the next star to Earth, other than the sun, is Alpha Centauri at some 4.4 light-years away. Scaling the Earth-sun street at one inch locations this star at 4.4 mile (7 km) distant.

See?

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The red star in the facility of this photo is Proxima Centauri, our sun’s nearest neighbor amongst the stars. A beam of irradiate from this star takes around 4 year to take trip to Earth. Picture via Max Planck Institute for Extraterrestrial Physics.

Familiar room objects, conceptualized

Scaling the astronomical unit in ~ one customs (2.5 cm), here are ranges to various bright stars, star clusters and galaxies:

Alpha Centauri: 4.4 miles (6.4 km)

Sirius: 8.6 mile (14 km)

Vega: 25 mile (40 km)

Pleiades open star cluster: 444 miles (715 km)

Antares: 555 mile (893 km)

Hercules globular star swarm (aka M13): 22,200 mile (35,700 km)

Center of our Milky way galaxy: 26,100 miles (42,000 km)

Great Andromeda galaxy (M31): 2,540,000 miles (4,100,000 km)

Sombrero galaxy (M104): 28,000,000 miles (45,000,000 km)

Whirlpool galaxy (M51): 31,000,000 mile (50,000,000 km)

And therefore on, earlier to approximately 13 billion+ light-years come the the furthest galaxies: 13,000,000,000 miles (21,000,000,000 km)

Okay, the numbers are still pretty big! but hopefully they can assist you see that our cosmos is an extremely vast.

There are 33 stars in ~ 12.5 light years of our sun. Click right into Atlas that the universe to discover an interactive web page that’ll allow you store zooming farther and farther out. Picture via Atlasoftheuniverse.com.

The fastest-moving stuff in the universe

As stated above, light travels at an significant 186,000 miles per second (300,000 km/sec). That’s an extremely fast. If you might travel in ~ the rate of light, girlfriend would have the ability to circle the Earth’s equator around 7.5 times in simply one second!

In various other words, a light-second is the street light travel in one second, or 7.5 times the distance roughly Earth’s equator. A light-year is the street light travels in one year.

How much is that? multiply the number of seconds in one year through the number of miles or kilometers the light travels in one second, and there you have it: one light-year. It’s around 5.9 sunshine miles (9.5 trillion km).

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This scale starts close come home however takes us all the means out come the Andromeda Galaxy, the most distant object most world can see through the unaided eye. Photo via Bob King/ Skyandtelescope.com.

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Bottom line: Here’s a means to recognize the range of light-years in miles and kilometers.