BLOOMINGTON, Ind. -- The annual Perseid meteor shower happens on warm summer nights, when gazing at the sky is a pleasure. This year the Perseids will peak on the night of Aug. 12-13. The moon will set around midnight, so moonlight will not interfere with observing meteors. In a clear sky there will be hours of dark viewing.
The Perseids will perform for most of August, though there will be fewer meteors to see the farther from the peak date you watch. If the peak is hidden by clouds, look for the bright streaks again as soon as the night sky is clear. Try to avoid artificial lights.
Face east and look about halfway up the sky from the horizon. You won't need binoculars or a telescope, because the meteors move much too fast for those instruments. The Perseids produce more of the extremely bright meteors called fireballs than any other shower. The chances of seeing a fireball will be greatest near dawn.
The Perseids may appear anywhere in the sky, but they will seem to originate from a point called the radiant in the constellation Perseus, which gives these "shooting stars" their name. The higher the radiant is above the northeastern horizon, the more meteors will be visible. Perseus is just north of the W-shaped constellation Cassiopeia in the Milky Way. Meteors near the radiant will have short trails because we see them nearly straight on, while those far from the radiant will look longer because they are seen from the side.
Most meteor showers happen when Earth crosses the orbit of a comet. The Perseids come from Comet Swift-Tuttle, and the meteors are caused by particles released from the comet's nucleus and left behind in space. As Earth plows through this stream of debris, ranging in size from sand grains to pebbles, each particle slams into our atmosphere at a speed of more than 30 miles per second and burns up almost instantly from friction with air molecules. The resulting heat momentarily creates a streak of glowing air that we see as a meteor. All of this happens about 60 miles above the ground, regardless of how close some meteors may appear.
Planets
Saturn will reach opposition on Aug. 27, and the ringed planet will be visible from dusk to dawn in the constellation Aquarius. At the start of the month it will rise by 9:30 p.m. local time and be 25 degrees above the southeastern horizon by midnight, well placed for viewing. A telescope will show the sunlit side of the rings, which will be tilted toward Earth.
Jupiter will dominate the morning sky, rising before 2 a.m. local time on Aug. 1 and at midnight on Aug. 31. An hour before dawn on Aug. 31, Jupiter will be 60 degrees high, a great target for visual observing. Its four Galilean moons will be visible in a small telescope.
Venus will be a bright evening star for a short period after sunset, standing 3 degrees high 30 minutes after sunset. It will be easy to find if you have a clear view of the western horizon. Venus is now on the far side of the solar system from Earth, so observers will have almost a full view of the planet.
Mercury will reach conjunction with the sun on Aug. 18. After that it will appear in the morning sky. On Aug. 31 Mercury will be about 10 degrees below the moon as the planet rises 80 minutes before the sun.
Mars will be north of Aldebaran, the brightest star in Taurus. Mars and Jupiter will gradually move closer until they are less than 1 degree apart on Aug. 14.
Moon phases
The moon will be new on Aug. 4, at first quarter on Aug. 12, full on Aug. 19, and at last quarter on Aug. 26.
Author: Hal Kibbey Email: hkibbey [at] gmail.com
The College of Arts