Astronomy

Astronomy test study guide

The Astronomy unit test will be on Tuesday, December 11, 2012 for Ms. Whalen’s class.

One theory that scientists believe is that the universe was created with a “Big Bang”. There are other theories about how the universe was created.

 Our universe is so large, it is beyond imagination. It continues to get bigger all the time.

 Ptolemy believed that our solar system revolved around the Earth. This was believed until Copernicus (scaredy cat) published his book, right before he died, that stated we were heliocentric (sun centered).

We live in the Milky Way galaxy. Milky Way galaxy is a spiral galaxy. Other types of galaxies are barred, elliptical, and irregular.

 A star is a huge hot ball of glowing gasses. When a star dies it implodes creating a supernova. Black holes are created when a large enough star dies. The mass of the star packs into a dense ball but its weight is the same. This causes an extreme pull of gravity. Anything that comes close will be pulled in. Nothing can escape its pull.

Gravity is the force that holds our universe together. Gravity keeps our planets in their oval orbits around the sun. The amount of mass something has determines how much pull its gravity has: The heavier the planet/star/moon, the stronger the pull of gravity.

 Our nine planets orbit around the sun (eight planets and one dwarf planet). My Very Excellent Mother Just Served Us Nine Pizzas: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto. The inner planets are the rocky planets. Past the asteroid belt, we have the gas planets. Pluto is an icy ball, but classified as a rocky dwarf planet.

There are other things that orbit around our sun such as asteroids and comets. A comet is a ball of ice, dust and gas. As it gets closer to the sun it speeds up and begins to melt. As it melts, the solar winds of the sun create a “tail” on the comet. When we see a comet, the light is seen for days or a week at a time. A meteor is space dust. As this dust enters our atmosphere the friction creates a spark that we might call a “shooting star”. The spark only last a few seconds. There are two times of year when meteor showers happen: August and November. An asteroid is a large chunk of rocky material in space. There is a large collection of asteroids orbiting the sun between the Jupiter and Mars called the asteroid belt.