This is the Dudley Observatory Skywatch Line for Monday and Tuesday, November 23rd and 24th written by Joe Slomka.
The Sun sets at 4:26 PM; night falls at 6:06. Dawn begins at 5:18 and ends with the Sun rising at 6:58.
As the sky darkens, only one bright object is seen – the Moon. The twelve-day-old Moon rises in the afternoon and appears about 94 percent illuminated. It borders Pisces and Taurus. Tuesday’s Moon appears fatter and rises about 4 PM. The Moon is due South between eleven and twelve PM on both nights. The Moon sets between five and six AM.
The night sky also contains outer planets Neptune and Uranus, along with asteroid 4Vesta. Neptune is located in Aquarius; Uranus is in Pisces. Vesta lies about two-and-a-half degrees from the star Iota Ceti. The almost “full Moon” is bright enough to make observations of these Solar System members difficult. Neptune sets at 11:47 PM, 4Vesta at 1:24 AM, and Uranus at 3:12 AM.
The famous variable star Algol, in Perseus, dims for about two hours centered on 12:15 AM Wednesday. All night observers can witness the star fade from second to third magnitude.
Pre-dawn skies continue the planetary parade. Bright Jupiter rises first near Leo’s hind leg at 12:48 AM. By 3 AM, it is high enough for observation. On Tuesday at 3:39 AM, sky watchers can see Jupiter’s moon Europa reappear from behind its planet. Wednesday, at 3:22 AM, astronomers can see the Great Red Spot, a giant storm, on Jupiter.
Mars rises, in Virgo, at 2:13 AM. Mars appears much dimmer than Jupiter. However, it brightens a little this month. The Red planet appears about sixteen degrees below Jupiter. Venus is the last to rise, at 3:06 AM, and lies about 11 degrees below Mars. Venus, at minus 4.2 magnitude, is second only to the setting Moon in brilliance. By Dawn, all three are in ideal heights for observation.
Followers of the Skywatch Line know that the Milky Way, which tonight stretches from horizon to horizon, represents the rim of our galaxy. They also know that the faint glow in Andromeda is that of a giant galaxy, similar to ours. However, these “island universes” are not isolated from each other. Their gravitational fields clump galaxies into groups. The Local Group is made of our Milky Way, Andromeda, M 33 in Triangulum, and about a dozen other galaxies. This group is traveling together through space. Some galaxies also interact with each other. A prime example is M 51, off the Big Dipper’s Handle. A telescope shows one galaxy stealing material from another. Some astronomers think that giant galaxies like our own grow by absorbing smaller ones. Colliding galaxies are common telescope sights. It is thought that two spiral galaxies will merge to form an elliptical galaxy. In about three billion years, Andromeda and the Milky Way will probably collide and merge. The result will be a giant galaxy marked by very active star formation.