A crescent moon snuggles up to the innermost planets this week, while sky-watchers will also see mythical twins reveal two stellar wonders.
Zodiacal lights. With the moon out of the early evening sky this week, ideal sky conditions prevail for hunting down the elusive zodiacal lights. This ethereal glow across the sky is caused by sunlight glinting off countless dust particles scattered between the planets.
Ancient Romans thought that the ghostly glimmer was due to far-off campfires below the horizon. The ancient Greeks speculated that it must be caused by distant volcanic explosions.
This most subtle of astronomical phenomenon is best seen in mid-northern latitudes by observers who are far from city lights. Look for a pyramid-shaped glow—fainter than the Milky Way—rising above the western horizon after sunset.
Moon and Venus. Early risers at dawn on Wednesday, February 26, can soak in a pretty pairing between a thin, waning crescent moon and the brilliant Venus. The two celestial objects will appear to be within 5 degrees of each other—equal to the width of your three middle fingers held at arm’s length.
For lucky observers in parts of western and central Africa, southeastern Asia, and most of India, the pairing will be much more dramatic. Earth’s companion will appear to actually eclipse (or occult) Venus at 5 a.m. GMT (see Earth map of occultation).
Since this will occur in the late morning—where the occultation is visible—it will be best seen through binoculars. The moon should be an easy target to pick up with the naked eye, however, as it will hang high in the southwest. Venus will appear as a white star near the upper horn of the crescent. The view through a small telescope will be even more dramatic because Venus appears as a tiny crescent as well.
Moon and Mercury. Next stop for the moon is Mercury, at dawn on Thursday, February 27. Binoculars should show Mercury to the lower left of the super-thin crescent moon, hanging very low in the southeastern sky about 30 minutes before sunrise. Looking down on them, to their far upper right, will be a brilliant Venus.
Gemini’s jewel box. On Saturday, March 1, a new moon heralds a dark evening sky, perfect for hunting down two gorgeous open star clusters nestled within the Gemini constellation. The Twins, as they are called, are fun to explore with binoculars and small telescopes, even from bright city suburbs.
The Twins are easy to find riding nearly overhead in the southern sky in midevening this time of the year, marked by the two bright stars Castor and Pollux. You’ll find starlike Jupiter nearby, located toward the lower right of the twin stars.
Now scan the skies with binoculars to the right of the brilliant king of planets. The Messier 35 star cluster lies about 8 degrees away, a little less than the width of your fist held at arm’s length. That is just a bit more than the field of view in standard 7 x 50 binoculars.
Sitting some 2,800 light-years away from Earth, M35 is a loose conglomerate of at least 100 diamond-like stars that lie scattered across an area the size of the full moon. Bright enough to be glimpsed as a 5.1-magnitude hazy spot with the naked eye (from a dark site), higher magnification is needed to really appreciate M35’s beauty. Compared to our sun, which is estimated to be about five billion years old, it’s amazing to think that these remote stars are likely only a fraction of that age, at 150 million years old.
Look carefully and you may notice a tiny, fuzzy patch of light on the southwest outskirts of M35; that’s another open cluster called NGC 2158. It lies about a half-degree from the center of M35—equal to the width of the full moon. Shining at magnitude 8.6, this horde of orange-hued red giant stars resides nearly four times farther away than M35, at some 12,000 light-years away.