This is the Skywatch Line for Monday and Tuesday, January 14th and 15th.
The Sun sets at 4:45 PM; night falls at 6:26. Dawn breaks at 5:43 AM and ends with the Sun rising at 7:23.
The First Quarter Moon dominates the sky. Monday’s Moon begins the evening in Pisces, but migrates into Cetus by nightfall. It blazes with minus 10th magnitude on both nights. The Moon sets at 1:14 AM on Tuesday and at 2:18 AM on Wednesday.
Mars, in Pisces, is the only easily seen planet. It appears about 88% lit, shines with zero magnitude and lies about 5º high in the South. It is best observed at 4:53 PM and sets at 11:10 PM.
Neptune occupies Aquarius, about 25º below and to Mars’ left. Neptune glows with 8th magnitude and appears a tiny 2.2 arc-seconds, 36º high; it sets at 9 PM. Uranus, in Pisces, is brighter with 5th magnitude and a larger 3.6 arc-seconds in our telescopes. However, it lies only 5º from the brilliant Moon, which hinders observation. Uranus is best observed at 6:06 PM and sets at 12:48 AM.
Comet P46/Wirtanen is still available for viewing. The comet is pulling away, so its image in telescopes is constantly shrinking and becoming dimmer. Wirtanen is quite close to the star Omega Ursae Majoris, which forms the nose of the Great Bear. Recent reports are the comet appears as a 6.6 magnitude haze. Up all night, it is best observed at 6:06 AM.
Finder charts for Neptune, Uranus and Wirtanen are available from various astronomy media.
Dawn brings new bright planets. Venus, in Ophiuchus, rises at 3:54 AM, flashing with minus 4th magnitude and about 16º high at Civil Dawn. Venus’ 22 arc-seconds in size appears as a 55% crescent. Jupiter shares Ophiuchus with Venus, but lies about 7º below. It glimmers with minus 1st magnitude and appears about 32 arc-seconds in size at an altitude of 9º above the eastern horizon.
Saturn returns to our skies by rising in Sagittarius at 6:39 AM. It glows at zero magnitude, appears about 15 arc-seconds in size, but is about 2º high in the East. It requires an unobstructed horizon to be seen.
By nightfall, Orion is already high in the southeastern sky. The bright white star Rigel marks the mighty hunter’s knee. A dim line of stars begins at Rigel and flows westward and downward until it disappears below the horizon. This is the river Eridanus. To see the full extent of this heavenly waterway, one must travel to Florida. There, Eridanus ends with the bright star Achernar, which literally means, “star at the river’s end.” The identity of this stream is a bit of a mystery. Ancient authors differ as to whether it refers to the Euphrates or the Nile. Both rivers were revered from time immemorial. Both were the sources of water and bountiful harvests. It is no coincidence that all civilizations and cities were founded along the banks of great rivers. The ancients thought of the Earth as an island surrounded by an immense body of water. The creation story in the Book of Genesis alludes to this view, as do Babylonian creation myths. The sky also bears out this vision. For the past several months we have been observing water related constellations. Delphinus (the Dolphin), and Capricornus (the Sea Goat), began the procession, followed by Aquarius, Cetus and Pisces. Eridanus spills its heavenly waters to sustain this celestial aquarium.
The Albany Area Amateur Astronomers hold their monthly meeting on Thursday, January 17th, at 7:30PM at miSci. Dr Evan Halstead will talk about “The Expanding Universe”. He earned bachelor degrees in physics and electrical engineering and a PhD in Physics all at the University of Buffalo. He is a cosmologist and professor of Physics at Skidmore College who has studied gravitational collapse, black holes, and Big Bang inflationary fields.
All club events are free and open to the public.