The bright planets, having kept the night sky interesting for the last several months, retire during May. Mars, Venus, Jupiter, Saturn and Mercury all cluster near the sun, out of sight to casual observers, for most of the month. Star watchers will have to be content with stars, which is quite an unusual state of affairs. A similar close grouping of planets and sun happened 21 years ago. At that time, some people were afraid that the combined gravity of the celestial bodies would disrupt life on Earth, causing earthquakes and perhaps even sending parts of California sliding into the sea.
Tidal forces can be quite spectacular, however.
The moon's gravity deforms Earth a few inches every day, and the resulting friction slows down Earth's rotation ever so slightly. Our day is about 15 seconds longer than it was a million years ago. The tidal force of the sun controls the rotation of Mercury, and Earth's rotation keeps the moon rotating only about once a month. Farther out in the galaxy, many double stars are pulled into egg shapes by their mutual tidal forces. The five planets, the moon and the sun will come together May 3-5, when they will fit into 27 degrees of sky.