Heading into the final days of September and first week of autumn sky-watchers will find the moon dancing with celestial luminaries like planets and stars.
Mercury and Spica. Within a half hour after sunset on Tuesday, September 24, look toward the very low southwest horizon for planet Mercury making a remarkably close encounter with Virgo constellation’s brightest star Spica.
The cosmic pair will appear to squeak past each other—well within 1 degree—the closest conjunction between a planet and such a bright star in 2013.
This cosmic duo, however, will be a real observing challenge because of its proximity to the horizon—so find a location that has a totally clear view of the southwest horizon and use binoculars. Also use Venus and Saturn as a convenient guidepost to tracking down Mercury/Spica. They will be about 22 degrees apart—little more than the width of two side-by-side fists at arm’s length.
The further south your observing location, the higher the pair will appear in local skies.
Moon and Aldebaran. Near midnight on Tuesday, and into the early morning hours of Wednesday, September 25, look towards eastern and southern skies for a stunning waning moon passing the left of the red giant Aldebaran—the bright “eye” of Taurus.
Earth’s natural satellite will appear less than three degrees from the 68 light-year distant star—equal to the width of your three middle fingers at arm’s length.
Continue watching the moon during daytime Wednesday as it glides through the southern sky and try your hand at catching sight of Aldebaran with the help of binoculars.
Last Quarter Moon. Last-quarter moon occurs on Thursday, September 26 at 11:56 pm EDT (Friday, 3:56 am UT). The moon rises in the east around midnight, so look for it passing between winter constellations Gemini, to the left, and Orion, on its right.
Moon joins Jupiter. At dawn on Saturday, September 28 the waning crescent Moon glides only five degrees south of the beacon-like Jupiter. The two will appear particularly pretty with binoculars, which if you hold steady enough will show off the gas giant’s four biggest moons.
Worlds Align. By next morning, Sunday, September 29, early bird skywatchers gazing towards the eastern sky will notice that the moon will have sunk between bright Mars, near the eastern horizon, and Jupiter, more than halfway near the zenith, forming a diagonal alignment of neighboring worlds not to be missed.