Astronomy test study guide
The Astronomy unit test will be on Tuesday, February 10th, 2015.
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. There is a massive black hole in the middle of our galaxy, but our
solar system is on the far outside edge and therefore we are in no danger.
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 star with
enough mass 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 and black holes never die.
Our sun is the
star that gives us light and heat. Life would not be possible without our sun.
It takes the Earth 365
days to revolve around the sun
(one year). It takes the Earth 24 hours
to rotate on its axis (one day).
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.
An eclipse occurs when something blocks the view of
something else in space. A lunar eclipse
is when the view of the moon is blocked by the shadow of the Earth: Sun, Earth, Moon. A Solar eclipse happens when the moon blocks our view (perspective) of the Sun: Sun, Moon, Earth.
Constellations
are groups of stars that create a picture. Constellations are used as a map of
the sky. Explorers used the North Star to help guide them. Constellations
appear to move as we travel through our season because we are revolving around
the sun. Because of this, some early societies used the constellations as a
calendar. The northern and southern hemispheres of Earth can see different
constellations.
