DSST Astronomy Review Questions and Answers

Astronomy the study of everything in the universe, from all the celestial bodies to space itself; greek for "law of the stars" (astron = star; nomos = law) Sun the star at the center of the Solar System, 27 million degrees at core, 99.8 % of mass in SS Nuclear Fusion Hydrogen atoms fuse together to make Helium (happens in core of Sun) Solar System the gravitationally bound system comprising the Sun and the objects that orbit it, either directly or indirectly Mercury the smallest and innermost planet in the Solar System; orbit 88 days; Roman = messenger to the gods; terrestrial planet Venus second planet from the Sun; orbit 224.7 days; Roman = goddess of love; spins opposite direction; terrestrial planet Earth the third planet from the Sun and the only object in the Universe known to harbor life, densest planet; orbit 365.2 days; terrestrial planet Meteorite a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the Earth's atmosphere and impact with the Earth's surface or that of another planet Space debris (junk, waste, trash, or litter) the collection of defunct man-made objects in space International Space Station a space station, or a habitable artificial satellite, in low Earth orbit; first component launched into orbit in 1998, now the largest artificial body in orbit Moon an astronomical body that orbits a planet or minor planet; often refers to an astronomical body that orbits planet Earth, being Earth's only permanent natural satellite Mars fourth planet from the Sun and the second-smallest planet in the Solar System; orbit 687 days; Roman = god of war; terrestrial planet