Exploring The Night Sky: What’s Out There?

1. Exploring The Night Sky: What’s Out There?

2. Celestial Objects • Any object in space is a celestialobject comets planets asteroids and meteoroids stars moons

3. Planets • Planet = a large, round, celestial object that travels around a star • Orbit = the path that a celestial object takes around another object • Solar system = the sun and all the celestial objects that travel around it

4. Planets • Recall that there are 8 planets in our solar system • Outer Planets • Jupiter, Saturn, Uranus, Neptune • Gaseous (called “Gas Giants”) • Mostly gas, ice and dust • Inner Planets • Mercury, Venus, Earth, Mars • Terrestrial (solid cores and rocky crusts)

5. So, what makes it a Planet? • Remember, a planet must: • Orbit a star (like the sun) and no other celestial object • Contain enough mass so gravity pulls it into a round shape • Clear other celestial objects out of its orbit • A dwarfplanet does not clear its orbit (sorry, Pluto ) • Planets are not luminous (they only reflect light, and do not produce it)

6. Stars • A star is a massive collection of gases that emit large amounts of energy • Stars are luminous (they produce their own light) • Our sun has a mass 340,000X larger than the Earth!

7. The Sun • Nuclear reactions occur in the core of the sun • Atoms of hydrogen (H) fuse to form atoms of helium (He) • These reactions release huge amounts of energy • The sun’s core reaches temperatures of ~15 million °C!

9. Features of the Sun • Sunspots = Dark area on the sun’s surface that is cooler than the surrounding areas • Solar Flare = Large explosions of gas and charged particles

10. Auroras • Auroras are produced when charged particles released by the sun come into contact with Earth’s magnetic field and atmosphere • Aurora Borealis at the North Pole • Aurora Australis at the South Pole

11. Why is our Sun Important? The Sun is important because: • It is the source of energy for ALL living organisms on Earth • Energy from the sun drives the climate and weather patterns we experience on Earth

12. But what about other stars out there? • Our Sun is the closest star to Earth (This is why it appears to us to be the brightest and largest star) • Constellation= group of stars in the sky

13. Constellations – Big Dipper & Little Dipper (Ursa Major & Ursa Minor)

14. Constellations - Orion

15. Constellations - Cassiopeia

16. Moons • Moon = a celestial body in orbit around a planet • Moons are not luminous • Reflect light from the sun • Scientists believe that 4.6 billion years ago Earth collided with an object the size of Mars • Molten rock from Earth flew out into space, forming the moon

18. The Moon • The moon has a nearly solid interior • Craters are created when asteroids collide with the moon • The moon is the only celestial object that humans have landed on

19. So, what else is out there? • Asteroids = small, rocky, irregular shaped celestial objects • Meteoroid= piece of rock or metal smaller than an asteroid • Streak of light when a meteoroid enters Earth’s atmosphere is called a meteor • Comet = large chunk of ice, dust and rock that orbits the sun • Glowing head and long tail Video of 2013 Russian Meteor

20. So, just how small are we? • Galaxy = a huge grouping of stars, planets and dust clouds • Galaxies are HUGE! • Contain between a billion (1,000,000,000) to a trillion (1,000,000,000,000) stars!! • We are part of the Milky Way Galaxy Lenticular Galaxy Irregular Galaxy Elliptical Galaxy Spiral Galaxy

21. Astronomical Measurements Objects in space measured using: Astronomical Units (A.U.) = The distance between the Earth and the Sun; about 150 million km Light years (ly)= the distance that light travels in one year; 9.46 X 1012km or 63241 A.U. Earth’s closest star (after the Sun) Proxima Centauri is still 4.2 ly away!! Earth’s next closest galaxy is thousands of light years away!!!

22. And, because you asked… A Black Hole…. • Black hole = a region of space with gravitational pull so strong that even light cannot escape What would it feel like to go through a black hole? (click to find out!) Do you think other life exists in the universe? (click)