Distances in Space

Earth and Moon From here on earth it is difficult to fathom the huge distances that exist between the stars and planets. The circumference of the earth (38,500 km) may seem like a long way to us but is an insignificant distance in space. The nearest celestial object to earth, the moon, is approximately 400, 000 km away (more than 10 times the earth’s circumference).

Earth and Sun The sun, which is by far the closest star to earth, is 150 million km away. That is so far aways that it takes light over 8 minutes to travel from the sun to the earth

Light Years As we leave the solar system, distances become so great that astronomers no longer refer to them kilometres. Instead they use light years. Light travels at a speed of 300,000 km/second (that’s 7.5 times around the earth in one second!). A light year is the distance that light travels in a year (9,460,800,000,000 km).

Closest Star The closest star to our solar system, Alpha Centauri, is 4.3 light years away. There are only 11 stars (not including the sun) that are less than 10 light years away from earth. Check out this scale diagram!!

Distant Stars Most stars are much farther away than that. Many stars that we see at night are several thousand light years away. This means that from earth we can only see these stars as they existed thousands of years ago. In fact, some of the stars we see at night no longer exist!

How Big Is The Universe? The most distant objects that have been detected are approximately 14 billion light years away.