1. An Astronomical Tour Objects in the Universe

2. Objects in our Solar System l A solar system is a collection of objects that are gravitationally associated with a star l Objects in our solar system include star, planets, moons, asteroids, comets, meteors

3. Active Sun viewed in X-rays -> <- Coronal loops

4. Planets l Objects that orbits (revolve around) a star l Mercury l Venus l Earth l Mars l Jupiter l Saturn l Uranus l Neptune (Pluto is a minor planet) l My very excellent mother just served us nachos

5. Mercury

6. Venus (UV)

7. Earth

8. Earth’s Moon

9. Earth and its Moon

11. Mars

12. Jupiter and the four Galilean Moons

13. Saturn and Its Larger Moons

14. Uranus (true and false color)

15. Neptune

16. Pluto and Charon (from HST faint object camera)

17. Our Solar System

18. The Planets (in size perspective)

19. Asteroids (Phobos, Deimos, Gaspra)

20. Asteroid Belt l Between the orbits of Mars and Jupiter is a large “belt” of asteroids l There are also groups of asteroids that orbit the Sun and cross the orbit of the Earth from time to time.

21. Comets and the Oort Cloud l Comets are “dirty snowballs” composed of frozen water and dust. As they approach the Sun they melt and leave a stream of water vapor and dust that is a “tail” l Scientists believe that these originate from a large region filled with comet cores called the Oort cloud.

23. Comet Halley (March 1986)

24. Moving Out… l Our solar system is a small part of a large collection of stars, gas, and dust called a galaxy. l Our galaxy is called the Milky Way galaxy and is a spiral galaxy.

25. Galaxies

26. HST Deep Field Photo of Galaxies

27. Star Deaths l When stars finish their life cycle they may explode or throw out shells of gas. Such an object is referred to as a nebula (pl. nebulae) l Nebulae are common objects in a galaxy.

28. Eskimo Nebula Orion Nebula

29. Carina Nebula Cat’s Eye Nebula

30. Sting Ray Nebula (young) Bug Nebula

31. Section of the Eagle Nebula

32. Other Objects… l There are special classes of stars called variable stars, neutron stars, pulsars and black holes. These may be stars in the process of evolving or the result of a star explosion.