Measuring+Distances+in+Space


 * Measuring Distances in Space **



Scientists use several special units for measuring distances in space. Because distances in space are so far, we cannot use traditional forms of measurement (e.g., feet, miles, or even kilometers)! The numbers would become to large to work with and make calculations very difficult.

 Let's discuss two of the measurements we use for space:

**1. Astronomical Units or AUs **

**AUs are used when measuring distance inside the ** **Solar System (from planet to planet, for example). **

 Astronomical units are based on the distance from the Earth to the Sun. This distance (equal to 93 million miles) is 1 AU. Earth to Sun = 1 AU

As you can see from the above diagram, Mars is located 1.52 AU from the sun.

Based on this, do you think Mercury would be less than 1 AU or more than 1 AU from the sun?

//If you said "LESS," you are right! //

**2. Light Years **  Outside of Solar System, distances are extraordinary and even beyond comprehension. Here, we measure distance based on how far light travels. We call the distance that light can travel in one year a light year. Distances to stars and other galaxies are measured in light years. We abbreviate it as "ly."

**Nothing travels faster than light! NOTHING! **

Light travels at a rate of about 186,000 miles per second.