This is Dudley Observatory’s Skywatch Line for Friday, October 9, through Sunday, October 11, written by Sam Salem.
On Friday, Sun rises at 7:02am and sets at 6:22pm; Moon sets at 2:20pm and rises at 11:22pm. The Moon reaches its last quarter phase at 8:40pm on Friday. At last quarter, the Moon is illuminated on its western side, towards the pre-dawn Sun. On Saturday and Sunday before dawn, let the waning Moon guide you to the zodiacal constellations Gemini and Cancer. The Moon will be shining in front of the constellation Gemini the Twins. Get up before dawn to view the Moon and Gemini much higher up in the sky. To the north of the Moon will be Gemini’s two brightest stars, Castor and Pollux. The other bright star beaming to the south of the Moon is Procyon, the Little Dog Star. When the waning crescent Moon rises at about 1am on Sunday, it will be positioned four finger widths above of the large open star cluster Beehive, or Messier 44, in constellation Cancer. During the hours before dawn, the Moon’s orbital motion will carry it somewhat closer to the cluster. To see Messier 44’s stars more easily, hide the Moon just below your binoculars’ field of view.
Venus, at magnitude –4.1 in constellation Leo, rises in deep darkness, almost two hours before dawn begins, in the east-northeast. Spot Regulus above Venus or to its upper right. In a telescope, Venus continues to shrink slowly into the distance. It’s now only 15 arcseconds in diameter.
Mars is closest to Earth this week. It appears 22.6 arcseconds wide. It won’t be as close and big again until September 2035. Mars’s opposition comes on Tuesday, the 13th. Mars rises in early twilight. As night comes on it glares fiery orange, at magnitude –2.5, low in the east. It climbs higher as the hours pass, then blazes at its highest and telescopic best around 1:00am in the south in constellation Pisces.
Jupiter and Saturn shine in the south during dusk and early evening, then they move to the southwest as evening grows late. Saturn sits 7 degrees to the left of Jupiter. The two planets will pass just 0.1 degrees from each other at conjunction on December 21st, low in twilight.
On Friday, Io reappears out of eclipse from Jupiter’s shadow around 8:27pm. Watch it slowly glimmer into view a little east of Jupiter. Right around that same time, Jupiter’s Great Red Spot should be transiting Jupiter’s central meridian.
Moon rises late this weekend. It is the perfect time to seek out dimmer, deep-sky objects. Consider searching out several of Aquila’s planetary nebulae: NGC 6804, NGC 6781, NGC 6741, NGC 6772, and NGC 6751. They range from magnitude 11 to 13. These dim objects attract Astro-photographers to get these beautiful dying stars to show up in longer exposures. An Oxygen-III filter can further help bring out their soft glow. If you’re looking for slightly brighter targets, turn your scope to NGC 6755 and NGC 6756, two open clusters located about 4.5 degrees west-northwest of Delta Aquilae. Nearby are also two globular clusters NGC 6749 and NGC 6760, 3.2 and 4.8 degrees east of Theta (θ) Serpentis, respectively.