Welcome to AST 112!

1. Welcome to AST 112! Instructor: Adam Blake

2. Planets • Earth is a planet in the solar system. • The planets in the solar system revolve around the Sun.

3. The Solar System • The Solar System consists of: • The Sun • All objects that have been captured by the Sun’s gravity (these objects orbit the Sun) • Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune • Asteroid Belt • The Kupier Belt • The Oort Cloud

4. Stars Are stars the largest “element” in the Universe?

5. Galaxies

6. The Milky Way • The Sun is one star among one hundred BILLION in the Milky Way Galaxy: The Milky Way NOT the Milky Way (why not?)

7. Structure of a Galaxy • Galaxies generally consist of: • A supermassive black hole • 100,000 solar masses to 18 billion solar masses (largest known) • The central bulge • The disk • Spiral arms (sometimes) • The halo • Large galaxies often have smaller satellite galaxies in orbit • Sometimes they get absorbed by the larger galaxy

8. Nebulae live in galaxies.

9. Star clusters also live in galaxies.

10. Galactic Collisions Sometimes they duke it out for millions of years!

11. Galaxy Clusters • The Milky Way Galaxy is one galaxy among 30+ in the Local Group

12. Galaxy Clusters

13. Galaxy Superclusters • The Local Group is one galaxy cluster among 100+ in the Virgo Supercluster

14. Hubble Ultra Deep Field

15. The Universe • Do superclusters form larger-scale structures? • What are the largest-scale structures in the Universe?

16. Cosmology

17. How it’s Built • The hierarchy: • Planets • Stars • Galaxies • Galaxy Clusters • Galaxy Superclusters • The rest of the Universe

18. Two questions to ponder… • When you look at the night sky, what is and what is not in our galaxy? • Why don’t galaxies look like a pile of sprinkles? They’re composed of lots of stars, right?

19. The Scale of the Solar System (Size Comparison)

20. The Scale of the Solar System(Orbit Comparison) • From the Sun to the Earth: 93 million miles • From the Sun to Neptune: 2.79 billion miles • The solar system is conveniently measured in Astronomical Units (AU) • 1 AU = 93 million miles • Distance from Sun to Earth

21. The Scale of the Galaxy • We need to use light years to describe the galaxy. • 1 LY is how far light travels in 1 year • Light travels 186,000 miles / second • 1 LY = 5.88 trillion miles

22. The Scale of the Galaxy • The star nearest to the Sun is Alpha Centauri • It is 4.4 light years from the Sun! • Side note: many of the stars that you can see are multiple stars

23. The Scale of the Galaxy • The diameter of the Milky Way is 100,000 LY • If the Milky Way were a football field: • Solar System becomes microscopic dot • Alpha Centauri is 4.4mm away • Millions of star systems are within arms reach

24. The Nearest Galaxy • The nearest “heavyweight” galaxy is the Andromeda Galaxy • 2.1 million light years away!

25. The Farthest Galaxy (that we can see) 13+ billion light years away and 600 million years old

26. Looking Back In Time Light travels 186,000 miles per second. On Earth, it seems instantaneous. But if we observe light from an object 2.1 million light years away, we see the object as it was2.1 million years ago.

27. “The Universe is full of magical things, patiently waiting for our wits to grow sharper.”