The huge yellow covering depicts a light-year; the smaller sized yellow covering depicts a light-month. Read an ext about this photo at Wikimedia Commons.

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Objects in our cosmos are extremely far away. They’re so far away the kilometers or mile aren’t a advantageous measure of your distance. So we speak of room objects in terms of light-years, the street light travel in a year. Irradiate is the fastest-moving stuff in ours universe. It travels at 186,000 mile per 2nd (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 – space vastly farther than one light-year away. And, if we shot to express a star’s street in miles or kilometers, we soon finish up through impossibly large numbers. Yet miles and kilometers are what many of us use to understand the distance from one place on planet to another. In the late 20th century astronomer Robert Burnham, Jr. – writer of Burnham’s Celestial Handbook – devised an ingenious means to portray the street of light-years in regards to miles and also kilometers.

Keep reading, because that a means to understand the vastness that the universe, using systems of street we know and use every day.

Burnham started by relating the light-year to the expensive unit – the Earth-sun distance.

One expensive unit, or AU, equals around 93 million miles (150 million km).

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

A light beam bring away 8 minute to take trip the 93 million mile (150 million km) native the sun 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 systems in one light-year and also the number of inches in one mile room virtually the same.

For basic reference, there are 63,000 astronomical units in one light-year, and 63,360 customs (160,000 cm) in one mile (1.6 km).

This exorbitant coincidence allows us to carry the light-year down to Earth. If we scale the astronomical unit – the Earth-sun street – at one inch, then the light-year ~ above this scale represents one mile (1.6 km).

The closest star to Earth, various other than the sun, is Alpha Centauri at part 4.4 light-years away. Scaling the Earth-sun street at one inch locations this star in ~ 4.4 miles (7 km) distant.


The red star in the facility of this picture is Proxima Centauri, ours 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 because that Extraterrestrial Physics.

Familiar room objects, conceptualized

Scaling the astronomical unit in ~ one customs (2.5 cm), below are distances to assorted bright stars, star clusters and galaxies:

Alpha Centauri: 4.4 mile (6.4 km)

Sirius: 8.6 miles (14 km)

Vega: 25 mile (40 km)

Pleiades open up star cluster: 444 miles (715 km)

Antares: 555 mile (893 km)

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

Center of our Milky method galaxy: 26,100 mile (42,000 km)

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

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

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

And for this reason on, ago to approximately 13 billion+ light-years come the farthest galaxies: 13,000,000,000 miles (21,000,000,000 km)

Okay, the numbers room still nice big! however hopefully castle can aid you view that our world is an extremely vast.

There room 33 stars within 12.5 light years of our sun. Click into Atlas that the universe to discover an interactive web page that’ll allow you store zooming farther and also farther out. Photo via Atlasoftheuniverse.com.

The fastest-moving ingredient in the universe

As pointed out above, irradiate travels at an incredible 186,000 miles per 2nd (300,000 km/sec). That’s really fast. If you could travel in ~ the speed of light, you would have the ability to circle the Earth’s equator about 7.5 times in simply one second!

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

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

This scale starts close come home however takes us all the means out come the Andromeda Galaxy, the most remote object most people can see with the unaided eye. Picture via Bob King/ Skyandtelescope.com.

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