The Sky This Week 13 – 20 June 2003
The Moon brightens the late evening and early morning sky this week. Last Quarter occurs on June 21st at 10:45 am Eastern Daylight Time. Luna’s path through the stars takes her through the southern summer constellations of Scorpius and Sagittarius. She skims along the southern horizon, basking in a golden glow caused by the attenuating effects of Earth’s atmosphere. By the week’s end she drifts into the star-poor reaches of the autumnal constellations, passing the brightening red planet Mars before dawn on the 19th.
The 15th marks the earliest sunrise for the year, and initiates a two-week series of events that define the summer solstice ìseasonî. Since the earth’s rotation speed is essentially constant and its revolution speed around the Sun is slightly variable, the times of earliest sunrise and latest sunset don’t coincide with the actual day of the solstice itself. This effect is more pronounced in the winter, when the interval between earliest sunset and latest sunrise is nearly a full month. In summer the interval is about two weeks, centered on the solstice, which occurs on the 21st at 3:10 pm EDT. Latest sunset occurs on the 28th, so we’ll still have the illusion that the days are getting longer even after the solstice occurs.
By the week’s end, late night and early morning skywatchers can perhaps take advantage of air swept clean by a summer thunderstorm to spot the rising cloud-like plume of the Milky Way. This is a sight best seen far from the city, but the summer Milky Way is bright enough to see from some suburban locations if the air is clear and dry enough. The Galaxy’s center lies just above the tail of Scorpius, and just to the right of the ìspoutî of the Sagittarius ìTeapotî asterism. Located some 30,000 light years from us, its mysteries are shrouded by dense fields of stars and interstellar dust. This is one of the most rewarding parts of the sky to ply with binoculars, so if you’re headed for the mountains or the shore, be sure to bring a pair with you.
Jupiter is now dropping perilously close to the horizon as evening twilight fades. Those of us who have followed his antics over the winter and spring months will be sad to see him go, and we must now be content with taking our last telescopic looks at him during the fading light of dusk. At 9:00 pm he’s only 30 degrees above the horizon, and by the week’s end he sets by 11:30 pm.
Planet watchers won’t have to wait too long to see another bright world enter the sky, however. Ruddy Mars rises by 12:30 am by the end of the week, and each passing night finds him up 3 minutes earlier. Mars is currently about half the brightness of Jupiter, but that will change dramatically over the next few weeks. Look for his distinctive ruddy glow in the south before sunrise for the next several weeks. He receives a call from the Moon in the wee hours of the 19th, when Luna will be just over two degrees away.
