Video Karl Gebhardt, HETDEX Project Scientist, explains how a McDonald Observatory telescope will look for dark energy. Play video |
GlossaryLight-year A unit of length used by astronomers to measure great cosmic distances. One light-year is equal to the distance light travels in one year, which is about 5.88 trillion miles or almost 800 times the diameter of our solar system. The nearest star is a mere four light-years away, while the nearest large galaxy lies about 2.5 million light-years from Earth. Astronomers also use another unit, the parsec, which is equivalent to 3.26 light-years. |
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