Last modified: Wednesday, May 7, 2003
STAR TRAK/May 2003
May offers lunar and solar eclipses
A total lunar eclipse on the night of May 15-16 will be the top attention-getter in May, even for those who don't normally watch the night sky. Observers in most of North America and all of South America, as well as western Europe and Africa, will see the full moon's color change from bright silver to dull copper as it passes through Earth's shadow. The event will not be visible in Asia and Australia.
The moon will first edge into our shadow at 10:03 p.m. EDT (2:03 Universal Time), but that won't be noticeable at first to casual observers. It will take a while for the moon to darken enough for anyone to see that something unusual is happening. The actual total eclipse will begin at 11:14 p.m. EDT (3:14 Universal Time) and end at 12:07 a.m. EDT (4:07 Universal Time). The moon will gradually regain its normal color as it emerges from the shadow, and finally it will be in the clear once more at 1:18 a.m. EDT (5:18 Universal Time).
For details about where the eclipse will be visible, see http://sunearth.gsfc.nasa.gov/eclipse/.
The moon's unusual color during a total lunar eclipse is caused by the orange light of sunsets and sunrises around Earth's rim being bent into Earth's shadow by the atmosphere (the same way a prism works). This orange light then reflects from the moon's surface the way sunlight normally does, making the moon appear anywhere from dark red to bright orange.
Weather can have varying effects on the moon's color during an eclipse, and so can atmospheric pollution of several kinds, so an exact prediction of the moon's appearance is not possible. The moon's northern side will probably be lighter than the southern part this time, since the moon will not be in the center of Earth's shadow.
The last total lunar eclipse was in January 2000. If weather conditions are poor for this one, you'll get another chance just six months from now when the next lunar eclipse occurs on the evening of Nov. 9.
On the morning of May 31, the moon will pass between Earth and the sun, causing a partial solar eclipse for most of Europe (except Spain and Portugal) and the Middle East as well as central and northern Asia, Alaska and the Canadian Arctic region. An annular (ring-shaped) eclipse of the sun will be visible beginning in northern Scotland and sweeping across Iceland and parts of Greenland. For details, see http://sunearth.gsfc.nasa.gov/eclipse/. Remember to use protective equipment whenever you look directly at the sun, even if it is partly covered. A good choice is a piece of number 14 welder's glass, which can be obtained for a few dollars at welding supply outlets.
Earth will plow through dust left behind in space by Comet Halley, causing the Eta Aquarid meteor shower that will peak on the night of May 5-6. Viewing conditions will be favorable, since the moon will be only a few days past new and will not interfere. This meteor shower is active for three or four days before and after its peak, but most of the activity happens an hour or two before dawn for observers in North America. Many of the meteors skim through the top of the atmosphere, producing long paths. In a dark, clear sky there should be about 15 meteors per hour, most of them high overhead. They will appear to come from a point in the constellation Aquarius, which will rise in the east after midnight.
As evening twilight falls during May, Jupiter will appear high in the west-southwest. Brilliant white as always, it will remain in view until well past midnight all month before setting in the west.
Between Jupiter and the point on the horizon where the sun disappeared you'll find Saturn, still bright yellow but fading as the weeks go by. Saturn will set more than three hours after the sun in early May but only about one hour after sunset by month's end. In June it will pass behind the sun and be lost in the solar glare.
Around the time that Jupiter is setting in the west after midnight, Mars will rise in the east. The red planet is getting closer to Earth each week and therefore appearing bigger and brighter to us as well. This glowing orange object will be high in the southeast by dawn, outshining all the stars in the sky at that time.
Venus will still be the brightest planet, but it will rise only one hour before the sun, appearing very low in the east about a half hour before sunrise.
Mercury will be even lower than Venus and much fainter, perhaps visible in binoculars to the lower right (east) of Venus during the last week of the month.
The moon will be new on May 1, at first quarter on May 9, full on May 16 (when it will be eclipsed), at third quarter on May 23 and new again on May 31.