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The Big Dipper is high in the sky at nightfall at this time of year, with W-shaped Cassiopeia low in the sky. If you look shortly before dawn, though, they’ve moved. The dipper is in the northwest, with Cassiopeia the same height in the northeast.
The stars haven’t moved at all, of course. Instead, they’ve changed position in our sky because Earth is turning on its axis. All the stars appear to revolve around the North Star — the point the axis aims at.
Except for the Sun, Moon, and planets, everything appears to turn together. The stars all maintain their relative positions from night to night, year to year, and even century to century. That unified rotation may have played a role in the name for everything there is: universe.
The word comes from Latin roots that mean “one” and “to turn.” So “universe” can be taken to mean “everything is turning together.” A 19th-century astronomy textbook, in fact, said that was what the word was intended to convey. Earth was a static platform around which everything else turned. Everything beyond Earth belonged to the universe.
A more-modern view of the word’s early meaning is “turned into one.” In other words, everything belongs to a single framework.
And today, universe means “everything there is” — including Earth. Our planet is no longer the hub of everything, but a part of it — bringing new vistas as it spins through the universe.
We’ll talk about a debate over the extent of the universe tomorrow.
Script by Damond Benningfield