1. Astronomic Distances

2. Solar system- planets and other objects like comets and asteroids that travel around the sun Background

3. Galaxy- a large grouping of stars in the universe – Made of multiple solar systems – There are billions and billions of galaxies. We live in the Milky Way Galaxy Galaxy

4. Universe Universe- everything in space that we know about – There’s only one universe – Made up of billions of galaxies

5. Putting it all together UniverseGalaxySolar System Made of many

6. AU- astronomical unit – The distance from the earth to the sun – 1AU=93 million miles Psst… earth is 93 million miles from the sun! – Used to measure closer objects in space (planets in our solar system) Distance

7. Light year—The amount of distance a beam of light will travel in one year – It’s a measure of distance, NOT time Can have light seconds, minutes, hours, days weeks, and months! – 186,282 miles per second/ 5,878,625,373,183 miles per year – Used to measure things really far away Galaxies, stars – When we see light from space, we’re looking back in time Light has to travel to get to us, so we’re seeing old light Distance

8. Parsec Parsec: a unit of length equal to 3.26 light years, or 30 trillion kilometers – Roughly 19 trillion miles

9. A final note In astronomy, scientists rarely use kilometers – Just too small! Like measuring a person in millimeters – Scientists only use kilometers to talk about the diameter of a planet, or how far away a moon is from the planet