The big yellow shell depicts a light-year; the smaller sized yellow shell depicts a light-month. Read an ext about this image at Wikimedia Commons.

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Objects in our universe are extremely far away. They’re so much away the kilometers or miles aren’t a advantageous measure of your distance. So we speak of room objects in terms of light-years, the street light travels in a year. Light is the fastest-moving stuff in our universe. It travel at 186,000 mile per 2nd (300,000 km/sec). And also thus a light-year is 5.88 trillion miles (9.46 sunshine kilometers).

But stars and nebulae – no to point out distant galaxies – room vastly farther than one light-year away. And, if we try to refer a star’s distance in miles or kilometers, us soon finish up with impossibly huge numbers. However miles and kilometers space what many of us use to understand the street 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 method to understand the vastness the the universe, using units of street we know and use every day.

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

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

Another means of looking at it: the expensive unit is a bit an ext than 8 light-minutes in distance.

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

A light-year, pictured as a mile

Robert Burnham noticed that, quite by coincidence, the variety of astronomical devices in one light-year and also the number of inches in one mile are virtually the same.

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

This exorbitant coincidence allows us to bring the light-year under to Earth. If we range the astronomical unit – the Earth-sun street – at one inch, then the light-year top top this range represents one mile (1.6 km).

The closestly star to Earth, 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 center of this photo is Proxima Centauri, our sun’s nearest neighbor among the stars. A beam of light from this star takes about 4 year to take trip to Earth. Picture via Max Planck Institute for Extraterrestrial Physics.

Familiar an are objects, conceptualized

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

Alpha Centauri: 4.4 mile (6.4 km)

Sirius: 8.6 mile (14 km)

Vega: 25 mile (40 km)

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

Antares: 555 mile (893 km)

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

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

Great Andromeda galaxy (M31): 2,540,000 mile (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 so on, ago to approximately 13 billion+ light-years to the farthest galaxies: 13,000,000,000 miles (21,000,000,000 km)

Okay, the numbers space still quite big! but hopefully castle can aid you check out that our universe is very vast.

There are 33 stars within 12.5 irradiate years of our sun. Click right into Atlas the the cosmos to uncover 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 mentioned above, light travels at an tremendous 186,000 miles per 2nd (300,000 km/sec). That’s very fast. If you could travel in ~ the speed of light, friend would have the ability to circle the Earth’s equator around 7.5 times in just one second!

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

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

This scale starts close come home however takes united state all the means out come the Andromeda Galaxy, the most remote object most human being can see with the unaided eye. Photo via Bob King/ Skyandtelescope.com.

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