Chapter 1 – Our Place in the Universe 1. Can you define the Astronomical Unit? A Light-Year? Astronomical unit- The mean distance between the Earth and the sun, about 98 million miles or 150 million kilometers. It is often abbreviated as AU. Light-year-A unit of astronomical distance equivalent to the distance that light travels in one year, which is 9.4607 × 1012 km (nearly 6 trillion miles). 2. What is a planet, a solar system, the Milky Way, a galaxy, the universe? The largest scale is the universe…
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