Starwatch Newsletter Minnesota Starwatch is a tape-recorded message describing the night sky in the Midwest, which can be called by telelphone number (612) 624-2001 It is updated montly, and is produced by the Department of Astronomy, University of Minnesota 116 Church Street SE, Minneapolis, MN 55455

April will be the best month in a long time to view the planets. In the evening sky just after sunset ALL the planets that are visible to the naked eye will appear. The brightest is Venus, which is low in the west near the horizon. Next brightest is Jupiter, which is much higher in the sky, and well around to the south of west. In between them are Mars and Saturn, with Mars a bit fainter, redder, and lower in the west. By the end of April even Mercury will appear, below Venus in the west, and setting just an hour after sunset. Mercury is always hard to spot, you'll need a clear western horizon, but this month the presence of the other planets will make it a little easier to find. The planets always make a pretty clear line on the sky, roughly following the ecliptic plane. Just follow this line past Venus in late April to look for Mercury.

The five planets we see together in the west this month are all that were known before the invention of the telescope. To ancient astronomers, these five planets were the great enigmas. The name planet means wanderer, and to the Greeks it was the way the planets wander relative to the stars that made them a puzzle. We can see that clearly this April, as Venus, Saturn, and Mars all converge on the constellation Taurus from day to day, 'till by the end of the month they will all be within about ten degrees of each other, the width of a fist held at arms length.

For astronomers like Aristarchus, Pythagoras, and Ptolemy the desire to be able to predict how the planets would wander in the sky led to some of the most sophisticated mathematical modeling of the ancient world. Their struggle was not just how to do the calculations, but to decide which paradigm was right: did the planets move around the sun, or around the earth? For 1500 years and more people argued, and sometimes executed each other, over the right explanation for the motion of the planets. Out of that conflict, modern astronomy was born, and with it the idea of scientific proof as a different way of knowing from the arguments based on religious or philosophical ideals that went before. Much of our modern world view stems from the revolution that transformed astronomy in the late Renaissance, when planetary orbits were finally explained correctly by Copernicus, Kepler, Galileo, and Newton. When we watch the planets moving together this month, we can remember how mysterious this was to so many people for so long.

Friday night telescope viewing begins at 8:00pm. Please call 612/626-0034 for more information.

The Minneapolis Planetarium offers a wide variety of programs for all ages. For more information, call 612/630-6150.

For those interested in the Minnesota Astronomical Society, call 651/649-4861 for information on their upcoming events.

Minnesota Starwatch is available on-line at http://www.astro.umn.edu/Outreach/pub_out.html.

This has been Minnesota Starwatch, produced by the University of Minnesota Astronomy Department in cooperation with WCCO Weather Center.

Last Updated: Wed Mar 27 12:23:13 2002