2.  Astronomy is everything in the universe such as planets, stars, moons, sun and asteroids.  2 theories explain the beginning of the Universe. Science really only focuses on one of those theories.  Big Bang Theory is where a cloud of rotating gases condensed, heated then cooled and collapsed. As a result this created our galaxy and solar system.

3.  As this cloud of gases condensed and exploded, several things formed.  The first thing that formed was the different Galaxies. There are 3 types of galaxies. Our Galaxy is the Milky Way. Yummmmm!  The second thing that formed was the Sun. It provided heat for the planets, including earth.  Next and last they earth began to take shape, form and grow.

5.  The time it takes for light to travel from the sun to earth is 1 AU.  Light Year- The distance light travels in 1 year  Light Minute- The distance light can travel in 1 minute  Light Hour- The distance light can travel in 1 hour.

6.  Geocentric- the model of the universe where the earth is the center and everything revolves around us.  Heliocentric- the model or theory that the sun is the center of the universe and everything revolves around the sun. This is the model that we use and has been proven.  We now know that Heliocentric is correct and has been proven by using technology such as telescopes.

9.  Two Scientist helped to explain why our solar system works the way it does.  Nicklaus Copernicus created the Heliocentric model and theory. This theory said that the sun was the center of the solar system.  He didn’t publish his findings. A man by the name of Johannas Kepler was his apprentice and he continued the research and published the research. Galileo had a big part in helping to prove the Heliocentric theory.  Ptolemy created the Geocentric theory. This explained that the earth was the center of the solar system and all planets orbited earth.

12.  Laws of Gravity say that if the sun is the center of our solar system then the sun holds the planets in order because of gravitational pull. Also that each planet has a gravitational pull on each other. Each planet that has moons hold gravitational pull on them in order to keep everything in place.

14.  Isaac Newton explained that gravity is and inertia holds the planets in orbit around the sun.  Inertia is when an object in in motion until forced to stop.  Gravity depends on the distance and mass of the object. For example the earth has more gravity than the moon because the earth has more mass(size).

15.  The earth orbits in an ellipse! Not a circle!  It takes 365 day for the earth to revolve 1 time around the sun. We call 1 revolution 1 year!  Rotation is different from revolution!  It takes 24 hours to rotate 1 time. This is the same as 1 day!  All planets rotate and revolve.

16.  1 rotation Is equal to 1 day

18.  One of the first major technologies of the time period.  The Hubble telescope is a telescope that is a satellite that allows us to explore the universe and our solar system. This helped to prove that the Heliocentric theory is correct.  We still use this telescope today. Many improvements have been made.  From hand held telescope, tripod scope, Hubble telescope.

19.  The telescope was used to help prove that star patterens and constellations' existed along with proving the heliocentric model.  Constellations are stars that are in patterns.  The Hubble telescope is used to explore other planets and galaxies.

21.  Spiral- these galaxies are huge in shape and contain stars, dust and gases. They are held together by gravity and are the like the shape of a pinwheel. They have large amounts of gases and dust. It has both young and old stars.  Elliptical- these galaxies also contain dust, stars and gases. They are held together by gravity and have a round to oval shape. The gases and dust are in small amounts and consist of mostly old stars.  Irregular-these galaxies are huge with large amounts of dust, stars, and gases held together by gravity. Has an irregular shape and contains old and young stars.