Introduction To Astronomy

1. Introduction ToAstronomy A little overview of what you might need to know for the 2011 STAR Test

2. Formed over 14 billion years ago Our Universe Our SOL-AR System Contains objects that: Reflect Light and Objects that give off light We live on a planet-an object that only reflects light from stars like our sun: SOL

3. Gravity • Gravity plays a big role in the SHAPES of objects in the universe. • It gives shape to the orbits of the planets, solar system, and even galaxies. The Sun’s gravity reaches the solar system and beyond, keeping the planets in their orbits. Gravity from Earth keeps the Moon and human-made satellites in orbit.

4. Milky Way Galaxy Our Solar system is located in one of the “spiral arms” of the Milky Way The Milky Way is just ONE of hundreds of billions of galaxies Each galaxy contains billions of stars

5. Types of Galaxies • Spiral • Elliptical • Irregular

6. Stars produce light • Stars are born in clouds of gas and dust called Nebulae • Nuclear Fusion creates Helium from Hydrogen • Helium can fuse to form Carbon • Heavier elements are formed from supernova explosions

7. Basic Star Types • Smaller red and yellow stars like the sun are called main sequence stars • Massive bright stars begin as white and blue stars • Supergiant stars form when massive stars die • Supernova is a massive explosion of a dying star

8. Color of Stars • The color of a star is related to the TEMPERATUE of the star • Hottest stars are blue and white • Yellow stars are medium temperature • Red stars are the COOLEST star…Cool meaning NOT HOT

9. Betelgeuse

10. Distances • AU (Astronomical Unit) the distance of the Earth from the Sun (1 AU ∼150 million km). Light Year is the distance that light can travel in year, which is 9.46 trillion km. • The Sun is about 93 million miles from the earth. The star nearest to the Sun is Proxima Centauri. Proxima Centauri is 4.3 light-years from the Sun (270,000 AU)

12. Our Solar System • Contains other objects that reflect light and orbit other bodies called satellites or moons. • Our moon: Luna has a lunar cycle of 28 days in which it revolves once around Earth and rotates on its axis in the same period. • Comets, asteroids and meteroids also reflect light.

13. Meteoroid A meteoroid is a sand to boulder-sized particle of debris. The visible path of a meteoroid that enters Earth'satmosphere is a meteor, commonly "falling star". If a piece impacts Earth it is called a meteorite.

14. Asteroids orbit within an area between Jupiter and Mars known as the asteroid belt

15. 1 Km diameter Meteor Crater, Arizona thought to have been formed by a 30m iron asteroid impacting at a speed 36 times speed of sound

16. Kuiper Belt The Kuiper Belt is a disk-shaped region past the orbit of Neptune extending roughly from 30 to 50 AU from the Sun containing many small icy bodies. It is now considered to be the source of the short-period comets.

18. Comet’s From The Oort Cloud The Oort Cloud is a spherical cloud of comets believed to lie roughly 50,000AU, or nearly a light-year, from the SunOort Cloud objects were formed closer to the Sun than the Kuiper Belt objects. Comets are never bigger than the size of a MOUNTAIN

19. Near Earth Objects • http://www.jpl.nasa.gov/news/spotlights/200702-neo.cfm

20. That’s All For Now…