Mars takes center stage for sky-watchers this week, enjoying a rendezvous with the moon and a pair of creatures straight out of the zodiac.
Moon and Mars
About 30 minutes after sunset on Monday, October 27, look toward the low southwest for the waxing crescent moon with orange-hued Mars to its left.
The red planet appears less than 10 degrees away from the moon, which is less than the width of your fist held away from you at arm's length.
By the next evening the moon will have risen above Mars.
As an added attraction for telescope users, the red planet will appear next to the famed Lagoon Nebula, located in the constellation Sagittarius. Also known as Messier 8, the giant star factory resides about 5,200 light-years from Earth. It is even visible as a hazy oval path in binoculars.
The Lagoon will appear less than 30 arc-minutes to the lower right of Mars. That's about equal to the width of the full moon.
Sea Goat Doubles
After nightfall on Thursday, October 30, look for the first-quarter moon to sit next to two fine double stars in the constellation of Capricorn, the Sea Goat.
Look to the right of the moon for the faint star system Beta Capricorni. Also known by its Arabic name of Dabih, this wide double star some 330 light-years away is faintly visible with the naked eye, but it really is best seen with binoculars. Binoculars will really show off the much fainter, 6.1 magnitude companion star.
The binary-system stars take some 700,000 years to orbit one another. The reason for this extremely long orbit is that they are 21,000 times farther from each other than Earth is from the sun. Meanwhile, to the upper right of the moon is another naked-eye double star known as Alpha Capricorni, or Algedi, meaning "the billy goat" in Arabic.
Physically unrelated to each other, the brighter member (3.6 magnitude) of this binary system lies 109 light-years away, while the other (magnitude 4.2) is 690 light-years distant.
The Eagle and Southern Fish
On Halloween Night, October 31, look for the moon be in line with two widely separated stars over the southern horizon.
Look toward the far lower left of the moon for the bright star Fomalhaut in the constellation Piscis Austrinus, the Southern Fish. To the far upper right of the moon will be the bright summer star Altair, the lead member of the constellation Aquila, the Eagle.
Mercury rising. Early-bird sky-watchers awake at dawn on Saturday, November 1, will find the solar system's innermost planet at its best morning appearance this year. On that day, it reaches its farthest separation from the sun, lying 19 degrees west of the sun and appearing about 9 degrees (less than the width of your fist held at arm's length) above the southeast horizon about 45 minutes before local sunrise.
Mercury now shines at magnitude -0.6, making it bright enough to spot with the naked eye, but binoculars will help in the hunt.
Telescope users may notice that Mercury now takes on the appearance of a quarter moon as it is lit from the side at this point in its orbit around the sun.
Mars and Snow Globe
As evening twilight sets in on Sunday, November 2, telescope users should look for the red planet parked next to the globular star cluster Messier 28 in the constellation Sagittarius, the Archer. M28 is about 18,000 light-years from Earth and stretches across some 60 light-years of the sky.