Astronomy news for the week starting Friday, May 27, 2005.
The week begins with the Moon in its waning gibbous
phase. Always true to form, it passes third quarter on
Monday, May 30, about the time it crosses the meridian to the
south, then thins in its waning crescent
phase towards new, which it will reach next week. As day-to-day
the crescent descends the morning sky into dawn, watch for the
growth of earthlight on the lunar
nighttime side.
As it orbits Earth, the Moon passes three planets. The tilt of the
orbit brings the Moon as much as five degrees north and south of
the ecliptic (the apparent
path of the Sun). As the Moon passes the two outer planets, Uranus and Neptune, it is
on the south side of the ecliptic, and therefore goes five degrees
south of Neptune on Saturday the 28th, and three degrees south of
Uranus on Monday the 30th. Far more obvious is the conjunction of
the Moon with Mars
the morning of Tuesday May 31, the Moon passing just barely to
the south of the red planet. The Moon will actually occult (or
cover) it, as seen from southern South America and parts of
Antarctica. Closest passage takes place in the midwest around 4 AM
CDT, about an hour and a half after Mars rises in the southeast.
Closest passage is in bright twilight in Eastern time, and about
the time Mars rises in the far western US and Canada.
Two other passages of note have Saturn,
lingering in Gemini, moving
seven degrees south of Pollux the
night of Monday the 30th, and Mercury in
superior conjunction with the Sun (when it is on the other side of
the Sun) the morning of Friday, June 3. Saturn, setting ever
earlier, is now down by 11:30 PM Daylight Time, leaving the evening
planetary sky to Jupiter, which
transits the meridian to the south in mid-twilight. Though still
a difficult catch, you might put on a serious watch for Venus, which sets
in the west-northwest also in mid-twilight, about an hour and a
half after the Sun. A
clear horizon is mandatory.
Late spring-early summer is the season of the Dippers, the Big one seen going over the north celestial pole in early evening,
the seven star figure among the most beloved of the sky. As the
Big Dipper (the main component of Ursa
Major) descends toward the northwest, the Little Dipper (in Ursa Minor) climbs yet higher, the
tail of Draco the Dragon in
between them. Far down below the pole is Cassiopeia, a remnant of fall, which though low, is
still visible for anyone north of about 35 degrees north latitude,
which includes most of the US and all of Canada. To the south of
the Dipper's handle find the two stars that make the modern
constellation Canes Venatici, and
to the south of that, the faint lacy cluster of Coma Berenices, "Berenices Hair."
