A group of single stars, star systems, star clusters, dust, and gas bound together by gravity
What is a galaxy?
200
the shortest main type of electromagnetic radiation
What are radio waves?
200
color, temperature, size, composition, and brightness.
What are the four characteristics used to classify stars?
200
Stars will more mass live shorter than stars with less mass.
What determines how long a star will exist?
200
about five billion years ago, a giant cloud of gas and dust collapsed to form our solar system.
How did the universe form?
300
The three types of galaxies are spiral, elliptical, and irregular.
What are the three types of galaxies?
300
refracting and reflecting
What are the two major types of telescopes?
300
to determine the chemical composition of a star.
Why do astronomers use pictographs?
300
it becomes a white dwarf, a neutron star, or a black hole.
What happens when a star runs out of fuel?
300
the observation that the farther away a galaxy is, he faster it is moving away from Earth, and cosmic background radiation, which is radiation left over from the big bang.
What are two pieces of evidence that support the big bang theory?
400
The name of our galaxy is the milky way.
What is our galaxy called?
400
because it is clearer on mountaintops than at sea level and light from cities do not interfere
Why are many large observatories located on mountaintops or in space?
400
Absolute brightness is the brightness of a star if it were at a standard distance from Earth.
Compare and contrast absolute and apparent brightness.
400
its outer layers will expand and it will become a red giant. Eventually, the outer layers of the red giant will drift into space and the remaining hot core will be a white dwarf.
What will happen to the sun when it runs out of fuel?
400
it will likely expand forever.
What do scientists conclude about the future of the universe?
500
To describe sizes and distances in the universe since those numbers are often very large or very small.
Why do astronomers use scientific notation?
500
a curved mirror is used to collect and focus light
How does a reflecting telescope work?
500
the apparent change in postion of an object when viewed from different places.
What is a parallax?
500
an object with gravity so strong that nothing, not even light, can escape. Astronomers can detect black holes indirectly. Gas near a black hole is pulled so strongly that it revolves faster and faster around the black hole. Friction heats up the gas and X-Rays can be detected.
What is a black hole and how can it be detected?
500
the expansion rate of the universe appears to be increasing.
What evidence has led scientist to predict that the universe will continue to expand forever?