When people started paying attention to those little points of light in the night sky, it didn’t take long to notice that there’s something a little different about a few of them.
Most of those points maintain the same relative positions from night to night — they don’t move with respect to each other. Those came to be known as the “fixed” stars, and the brightest of them formed the classical outlines of the constellations.
But a few of them did change position — they “wandered” through the background of fixed stars from month to month, or even night to night. So these objects were given special designations. The Greeks called them planetes — the wanderers. And today, we still know them as “planets” — objects that spice up the night sky with their roving ways.
In fact, two planets are wandering past each other in the morning sky — Venus and Saturn. Venus is the brilliant “morning star,” low in the eastern sky at first light. Much-fainter Saturn is close to its left or lower left tomorrow, but will stand above Venus on Tuesday.
It made sense to early skywatchers that the planets were closer to Earth than the “unmoving” stars. But it took millennia to work out just how much closer. While the visible planets are all within about a billion miles of Earth, the visible stars are typically millions of times farther — so remote that they provide a stationary background for the motions of the wandering planets.
Script by Damond Benningfield, Copyright 2012
For more skywatching tips, astronomy news, and much more, read StarDate magazine.