Vocabulary
asterism A group or cluster of stars that appear close together in the sky.
black hole The super dense core left after a supergiant explodes as a supernova.
constellation An apparent pattern of stars in the night sky.
light-year The distance that light travels in one year; 9.5 trillion kilometers.
main sequence star A star that is fusing hydrogen atoms to helium; a star in the main
portion of its ”life.”
nebula An interstellar cloud of gas and dust.
neutron star The remnant of a massive star after it explodes as a supernova.
nuclear fusion reaction When nuclei of two atoms fuse together, giving off tremendous
amounts of energy.
parallax A method used by astronomers to calculate the distance to nearby stars, using
the apparent shift relative to distant stars.
red giant Stage in a star’s development when the inner helium core contracts while the
outer layers of hydrogen expand.
supernova A tremendous explosion that occurs when the core of a star is mostly iron.
star A glowing sphere of gases that produces light through nuclear fusion reactions.
Points to Consider
- Although stars may appear to be close together in constellations, they are usually not
close together out in space. Can you think of any groups of astronomical objects that
are relatively close together in space? - Most nebulas contain more mass than a single star. If a large nebula collapsed into
several different stars, what would the result be like?