The Sun
Stars
Life Cycles of Stars
Groups of Stars
Vocab
100
The sun's energy is produced in its central region by the fusion of hydrogen nuclei into helium nuclei.
How does the sun produce energy?
100
Astronomers measures the parallax of nearby stars to determine their distance from Earth.
How can the distance to a star be measured?
100
A star is formed when a contracting cloud of gas and dust becomes so dense and hot that nuclear fusion begins.
How do stars form?
100
Astronomers have determined that more than half of all stars are members of star systems.
How are stars distributed in space?
100
The visible surface of the sun.
What is the photosphere?
200
The sun remains stable because the inward pull of gravity balances the outward push of thermal pressure from nuclear fusion.
Why does the sun remain stable over time?
200
Astronomers classify stars be their color, size, and brightness. Other important properties of stars include their chemical composition and mass.
How do astronomers categorize stars?
200
A star's mass determines the star's place on the main sequence and how long it will stay there.
What determines how long a star remains on the main sequence?
200
There are three basic kinds of star clusters: open clusters, associations, and globular clusters.
What are the characteristics of each type of star cluster?
200
A sudden release of energy from the sun.
What is a solar flare?
300
The sun's interior consists of the core, the radiation zone and the convection zone.
What is the structure of the sun?
300
Most stars have a chemical makeup that is similar to the sun, with hydrogen and helium together making up of 96 to 99.9 percent of the star's mass.
What elements are found in stars?
300
The dwindling supply of fuel in a star's core ultimately leads to the star's death as a white dwarf, neutron star, or black hole
What happens to a star when it runs out of fuel?
300
Astronomers classify galaxies into four main types: spiral, barred-spiral, elliptical, and irregular.
What are the four major types of galaxies?
300
The distance that light travels in a vacuum in a year.
What is a light year?
400
Features of the sun's atmosphere include sunspots, prominences, and solar flares.
What are some features of the sun's atmosphere?
400
H-R diagrams are used to estimate the sizes of stars and their distances, and to infer how stars change over time.
How do astronomers use H-R diagrams?
400
A white dwarf takes about 20 billion years to cool down completely.
How long does it take a white dwarf to cool down completely?
400
Astronomers estimate that the oldest globular clusters are about 12 billion years old.
How old do astronomers estimate the oldest globular cluster is?
400
How bright a star really is.
What is absolute brightness?
500
About 300,000km thick.
How thick is the Radiation Zone of the sun?
500
About 600,000 million kilometer
What is the distance of Earth's rotation around the sun?
500
A black hole is an object whose surface gravity is so great that even electromagnetic waves cannot escape from it.
What is a black hole?
500
The Milky Way is a spiral galaxy.
What kind of galaxy is the Milky Way?
500
An explosion so violent that the dying star becomes more brilliant that an entire galaxy.
What is a super nova?
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