1. Our Place in Space

2. The Scale of the Universe Imagine (don’t write down): – You are driving on the 401 at 100km/h – You accelerate until you are going 280 times as fast – You head toward Neptune. How long do you think it will take you to get there? Answer: 50 years

3. The Scale of the Universe https://www.youtube.com/watch?v=The Scale of the Universe AMNHThe Scale of the Universe AMNH

4. Measuring Distances One of the biggest challenges astronomers face in modeling and mapping the universe is measuring distances. Astronomical RangeTypical Units Distances to satellites kilometres Planetary distances astronomical units Distances to nearby stars parsecs, light-years Distances at the galactic scalekiloparsecs Distances to nearby galaxiesmegaparsecs

5. Measuring Distances Astronomical Unit (AU): ~150 million kilometers (average distance from Earth to Sun) – Useful for measuring distances in the solar system

6. Measuring Distances Astronomical units are a more manageable way to measure distances.

7. Measuring Distances Light Year (ly): The distance that it takes light to travel in one Earth year = 63 241.077 astronomical units = 9.46 x 10 12 km

8. Measuring Distances The Sun is ~0.000016 ly away from Earth. Light from the Sun takes ~0.000016 years (or 8 minutes) to reach us.

9. Measuring Distances Parsec (pc): equal to 3.26 light years – Good for measuring large distances (galaxies, galaxy clusters

10. Think-Pair-Share What unit might you use to measure the distance to? A meteor burning up in Earth’s Atmosphere The next nearest star to our sun The distance to the Andromeda galaxy Distance to Neptune Kilometers Light years Parsecs Light years

11. Parallax Parallax is a tool used to measure distances to stars. Parallax is the change in position of an object viewed from two different locations Example: pointing to an object, closing an eye As the distance increases, the parallax angle decreases.

12. Overview of Our Solar System Consists of: – The sun – Eight Planets & their moons – Dwarf planets – All other celestial objects travelling around the sun (e.g. Comets, meteors, etc.)

13. The Planets To be a ‘planet’, a celestial object must: – Be in orbit around a star (eg. The sun) – Have enough mass to be pulled into a stable shape by gravity – Dominate its orbit

14. Dwarf Planets A dwarf planet is a celestial object that orbits the sun and has a spherical shape but does not dominate its orbit

15. Dwarf Planets There are currently 5 dwarf planets: – Ceres – Pluto – Haumea, – Makemake – Eris

16. Dwarf Planets Astronomers estimate there may be up to 2000 dwarf planets, with many located in the Kuiper Belt region of the solar system.

17. Moons and Satellites A moon is a type of satellite: a celestial object that travels around a planet in a closed path. To date, Saturn has had 53 moons identified!

18. Try This: Page 314 #1-5 (A,B,C)