This document discusses key concepts relating to distances and motion in space: - Revolution is the orbit of an object around another body like a star, while rotation is spinning on its own axis. - Perihelion and aphelion refer to the closest and furthest points in an object's orbit around the sun. - According to Kepler's laws, planets move faster when they are closer to the sun at perhelion compared to farther away at aphelion. - The distances between objects in space are measured in astronomical units (AU) and light years. One light year is the distance light travels in one year.

1. Distances in Space

2. Rotation – the spinning of a body on it’s axis Revolution – the spinning of a body around another body (ex. sun)

3. Perihelion An object’s position closest to the sun along it’s orbit

4. Aphelion An object’s position furthest from the sun along it’s orbit

5. Draw and Label Draw the diagram and label APHELION and PERIHELION

6. Draw and Label Draw the diagram and label APHELION and PERIHELION

7. Think about Kepler’s Laws of Planetary Motion… At which position would the planets move faster? Perihelion of Aphelion? Why? Animation

8. ONE MINUTE PAPER (to be turned in) Answer the following question in about 1-2 minutes. Focus on your answer, since the time is limited. Is it possible for Earth to be at Perihelion and Mars to be at Aphelion? Explain. Draw a diagram of how this would look.

9. How do scientists measure Distance in Space Podcast /article Parallax – see change in apparent position based on location Newer technologies such as radar

10. The distance from Earth to the sun is 1 AU (Astronomical Unit) about 93 million miles We can compare the distances in the solar system by AU’s But what if something is extremely far away?

11. Light Years The distance it takes light to travel in one year Is the same as: 6.324×10 4 AU or 5.879×10 ¹² mi To Infinity…and Beyond