The Moon, imaged 2021 April 20, 01:31 UT from Alexandria, Virginia
with an Explore Scientific AR102 10.2-cm (4-inch) f/6.5 refractor, Antares 1.6X Barlow lens, and a ZWO ASI224MC CCD imager.
The Moon waxes as she arcs through the stars of the Great Winter Circle this week. Full Moon occurs on the 16th at 11:56 am Eastern Standard Time. February’s Full Moon is popularly known as the Snow Moon, since February is typically the snowiest month of boreal winters. Abundant snow and cold temperatures also impact provisions stored for the season, so another name is the Hunger Moon. On the evening of the 9th you will find the Moon between the ruddy star Aldebaran and the Pleiades star cluster; on the 13th she passes close to Pollux, the brighter star of the Gemini twins.
Although February is the year’s shortest month, it is the one when most of us really begin to notice the increasing length of daylight. This week the length of day is one hour longer than it was back on the winter solstice, and we tack on nearly another hour by the month’s end. On average each day is about two and a half minutes longer than its predecessor, and this rate will be maintained through the upcoming equinox in March. If you enjoy early evening stargazing, take advantage of the next few weeks. The switch to Daylight Time will happen on March 13.
This is a great week to take long, leisurely looks at our only natural satellite, the Moon. I often say the Luna is “looked over, then overlooked” by neophyte astronomers. It is often the first target that new telescope owners look at, but often that first look is rarely followed up. The Moon’s surface is frozen in geological time; it has hardly changed over the course of the last billion years. However, these features offer a testament to the violent beginnings of the solar system itself. The large, seemingly flat features dubbed “seas” by early telescopic observers are the remnants of colossal collisions with planet-sized objects that abounded in the formative days of our planetary system. These collisions allowed molten rock from the proto-Moon’s interior to flood large areas of its surface. The brighter “highland” terrain provides a record of the ferocity of this early bombardment as countless smaller “planetessimals” pockmarked the surface shoulder-to-shoulder. As the terminator line slowly moves across the Moon’s face these features are gradually revealed, and it is always interesting to examine them as the lighting conditions change. What I enjoy in my evenings with the Moon is the sheer number of these ancient scars of violent formation, and the uniqueness of each one.
As the Moon brightens, though, she washes out the fainter stars of the night sky. Fortunately, about one third of the brightest stars in the night occupy this part of the sky, so the Moon won’t be the only thing to attract your attention. As much as I enjoy looking at the Moon through my smaller telescope, sweeping past all of the bright stars of the Great Winter Circle is also a rewarding experience. Starting with the bright stars of Orion, then moving around the circle counter-clockwise, each star shines like a brilliant gemstone. Betelgeuse and Aldebaran remind me of garnets, Capella is a blazing point of amber, while Rigel and Sirius are dazzling sapphires.
Jupiter can still be seen shortly after sunset in the southwest, but he beats a hasty retreat before the end of evening twilight, setting at around 7:00 pm. He will disappear by the end of the month, passing behind the Sun in early March.
Venus has seemingly vaulted into the morning sky. After the recent string of cloudy days I was surprised by her glowing presence in the southeast when I arose at 6:00 am. She will linger in this area of the sky for the next few weeks, drifting eastward against the dim autumnal constellations.
You will find ruddy Mars several degrees below Venus’ bright glow. The two planets will move in tandem for the rest of the week, gradually edging closer together. They will remain a “duo” through most of March.