Galaxies
what is a Galaxies?
a huge collection of gas, dust, and billions of stars and their solar systems, all held together by gravity.
Parallax is used to determine a star's
Distance from Earth
The brightness of a star as seen from Earth is called what?
C. Apparent brightness
The most massive stars collapse to form __________ when they die.
Black Hole
Another word for absolute brightness: _________
Luminosity
Scientists classify stars based on temperature and size.
True
Which of the following is a major difference between elliptical galaxies and spiral galaxies?
Elliptical galaxies have almost no gas or dust between stars.
A dying high-mass can explode, becoming a what?
D. Supernova
A dying high-mass star can suddenly explode to become a ____________
Supernova
Name the scientist who supported the theory of the big bang.
Edwin Hubble
Where is the center of the universe?
Has no center
A star is born when
Nuclear fusion stars
Many stars belong to larger groups called what?
A. Star cluster
Astronomers have discovered we can only see very little of the mass of galaxies where the remaining mass is known as ___________.
Dark matter
What is the force that allows the planets to orbit the sun?
Gravity
Dark Matter is the force that is causing the expansion of the universe to accelerate.
False- Dark Energy
Which of the following is not a characteristic of stars?
C. Texture
What uses powers of ten to write very large or small numbers in shorter form?
B. Scientific notation
Galaxies that are active young galaxies with giant black holes at their centers are known as __________.
Quasars
What galaxy is Earth apart of?
Milky Way
How are Galaxies formed
out of immense clouds of gas that collapse and rotate
The theory astronomers have developed to describe the formation of the universe in known as what?
D. Big Bang Theory
Gravity pulled most of the gas into the center of the disk, where the gas eventually became hot and dense enough for nuclear fusion to begin and what was born?
The Sun
Galaxies that appear to have a bulge in the middle and arms that move outward are called ____________.
Spiral galaxies
When was the universe formed?
5 billion years ago