Download Galaxies and Stars Questions KEY

Grade 8
Science
Unit: 11 Lesson: 02
Galaxies and Stars Questions KEY
1. What are galaxies?
Galaxies are massive systems, bound by gravity, and consisting of stars and remnants of dead stars;
galaxies are an interstellar medium of gas and dust.
2. What are the types or categories for galaxies?
There are three major types of galaxies: spiral, irregular, and elliptical. Also, there is a quasar galaxy.
3. What is a nebula?
A nebula is a cloud of interstellar gas and dust from which stars form.
4. Where do stars begin their life?
Stars begin their life in a stellar nebula.
5. What force helps a star begin to form?
Gravity is the force that helps a star to begin to form.
6. What is the relationship between mass and the lifespan of a star?
Generally, stars with more mass have shorter life spans because they burn their fuel more quickly than
smaller stars do. The mass also determines which direction the lifespan goes and ultimately, determines
what the star becomes when it dies.
7. What is the outcome of a star that runs out of hydrogen?
The center of the star shrinks increasing the internal temperature. This extra heat and pressure allows helium
to fuse, which causes the outer part of the star to expand forming a red giant or supergiant, depending on its
original mass.
8. What kind of stars become white dwarfs?
Main sequence stars, specifically small and medium stars, become white dwarfs.
9. What causes neutron stars to form?
After a high mass star becomes a red giant or super red giant, the gravity is so strong it causes the star to
contract again. This contraction causes new and different types of nuclear fusion to take place, which
causes the star to explode into a supernova. If the left over remains are about three times the mass of the
Sun or less, the remaining mass will contract back into a very small ball of neutrons. Neutron stars are so
dense that a section the size of a grain of sand will have the mass of a large plane. *Note - This explanation
is much more detailed than what is needed for a student, but has been done to provide teachers a detailed
explanation of what is happening.
10. What forms black holes?
The remnants of the most massive stars that collapse upon themselves form black holes.
11. What are the stages of a low/medium sized main sequence star?
Nebula, protostar, star, red giant, white dwarf, and black dwarf are the stages of a main sequence star’s life.
12. What are the stages of a massive main sequence star?
Nebula, protostar, star, supergiant, supernova, and neutron star or black hole are the stages of a massive
star’s life.
13. What is the closest star to the Earth?
Sun
14. What size star is our Sun?
Medium
15. Where is our Sun located in the Milky Way galaxy?
Our Sun is located at the edge of the galaxy.
©2012, TESCCC
06/03/13
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