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What is the modern explanation for "guest stars" that appear in the night sky and then disappear?
Stars that go nova or supernova and appear as bright objects during the event
What is the modern explanation for what the ancient Chinese called "guest stars"?
They are Nova or Supernova.
According to the Ptolemaic (Greek) system, the planets have circular orbits.
True
In the Ptolemaic (Greek) model of the universe, the stars are attached to the ________
celestial sphere
When viewing the planets, Mars appears to move backwards, or retrograde, because ________.
it is rotating around the sun slower than the earth's rotation
