SKYLIGHTS

Astronomy news for the week starting Friday, March 26, 1999.

The Moon brightens to full this week, reaching the phase the night of Wednesday the 31st just about moonrise in the US. This full Moon is the second in the month and the so-called "blue moon." There are usually three full Moons is a season, and all have a variety of names associated with them ("Egg Moon,", "Harvest Moon," etc.). According to an article in the May issue of "Sky and Telescope" by D. W. Olson, R. T. Feinberg, and R. W, Sinnott, the term "blue moon" was originally used in the "Maine Farmers' Almanac" to describe the third full Moon in a season that contained four full Moons so that the names would come out right. Articles written in the magazine in the 1940s, and subsequent propagation, mistakenly converted the term into the second full Moon in a month, which is how it is used today. March's "blue Moon" is oddly the second in the year (the first one last January), a rare event. As a corollary, there were no full Moons in February. Since the Sun just passed the vernal equinox, this full Moon (we could call it either the Sap Moon or the Egg Moon as it takes place just as March turns to April) is the closest of the year to the autumnal equinox in Virgo, the full Moon rising just up and to the right of Spica. As the seasons turned to Spring, Jupiter was being overtaken by the Sun. This week, on Thursday, April 1, the planet passes conjunction with the Sun and is totally invisible. It will next be seen in morning twilight later in April. But while missing Jupiter, we can admire far brighter Venus. Climbing ever higher in twilight and becoming brighter each night, the planet is the first object after the Moon to be visible as the sky darkens. Below it, you can still see Saturn, the two planets getting farther apart as Venus pulls away from the Sun and Saturn moves toward it.

With most of the planets bunched rather near the Sun, Mars and Pluto are the oddballs. Mars, now moving retrograde in western Libra to the east of the first magnitude star Spica, rises around 8:30 PM and glows redly (and brighter than all the stars but Sirius) to the south around 2 AM, by which time the planet's rival in color, Antares in Scorpius, will be above the southeastern horizon.