Star Talk : The month of the planets
Posted on Sunday, March 30, 2008
URL: http://www.nwanews.com/bcdr/News/60249/
Now it is spring, and each season, indeed each month, brings its own celestial wonders into view. April is no exception.
One might well call April the month of the planets because these are well seen this month, and we will probably have better weather for observing these wanderers than we had in a very rainy March.
First, however, on the night of April 8, the waxing crescent moon crosses the bright Pleiades star cluster. This event would be best seen at a dark location with a good pair of binoculars. The Pleiades looks like “ a little Big Dipper. ”
What I mean is that the stars of the Pleiades star cluster form a sort of compact “ dipper-shaped” group of stars in themselves, with seven bright members. The Pleiades is a good test of your ability to detect faint light sources. It is easy to see the five brightest members of the cluster with the naked eye, and quite a few people can see a sixth star.
A few can see the seventh star of the ‘ Seven Sisters’ (another name for the Pleiades ) with the naked eye, but I am not one of them. When the moon passes in front of the Pleiades, this is not a good time to test your faintstar-detection abilities. The moon will be too bright, and it will blot out your attempts. Binoculars will reveal many more stars than the original seven identified in ancient times. It is interesting to see the moon, which is moving toward the east, blot out some of the stars, a phenomenon that binoculars and patience would reveal over a twohour period.
Mars hangs west of overhead in April, and has the ruddy appearance one would expect of the Red Planet. Alas, the distance between Mars and Earth is rapidly increasing. This makes Mars appear as a small red dot or tiny disk in amateur telescopes.
Saturn, the ringed marvel of the planets, will lie nearly overhead by the end of April. One way to look for it is by noting that when the moon is absent, Saturn will be the brightest point-like object in the night sky. Also, if the air is steady enough, Saturn will not twinkle as will the stars. In effect, stars are exceedingly small points of light that are quite affected by the turbulence in the night air. Saturn, indeed any visible planet, is a larger mote of light and is less disturbed by Earth’s atmosphere, even though these objects, too, are small to the naked eye.
Bringing up the end of the parade of planets in April is mighty Jupiter. It rises at 3 a. m., so one needs to really be intrepid to see it. A better time would be about 6 a. m. and after. It will be in the southeast to east as April comes on. Here again, with good binoculars, one could make out a disk, and one could also see four of Jupiter’s moons. Brace the binoculars against something solid to get a steady view. Uranus and Neptune are not really naked-eye planets, and Venus and Mercury, which can be seen with the naked eye, will be either too close or entirely behind the sun to be seen from our earthly viewing point. Fair skies to all and a wonderful new season — new flowers by day, stars by night.
• • • David Cater is a professor at John Brown University and has been an avid stargazer for more than 45 years. He can be reached at dcater @ jbu. edu.