Skywatch Line for Wednesday, March 6th, and Thursday March 7th, 2019

This is the Dudley Observatory Skywatch Line for Wednesday, March 6th, and Thursday March 7th, written by Louis Suarato.

The New Moon phase occurs at 11:04 a.m., Wednesday. During this phase, with the Moon between the Sun and Earth, sunlight illuminates the side of the Moon facing the Sun, and, temporarily, leaves the side facing Earth without light. So, the idea of permanent dark side of the Moon is a myth. As the Moon’s orbit around the Sun gradually illuminates more of the lunar surface seen from our perspective, the amount of sunlight on the opposite side of the Moon decreases, and the amount of sunlight increases, or waxes, on the Earth side. When Moon and Earth form a 90 degree angle to the Sun, one quarter of the Moon is illuminated as we see it. A brief dark side of the Moon occurs on the far side only during a Full Moon, when the Earth is between the Sun and Moon.

A challenge will be to see the 1.6% illuminated, waxing crescent Moon before it sets at 6:54 p.m. Thursday. Mercury is briefly visible above the western horizon before it sets at 5:54 p.m. Wednesday. Mars, after spending the day between the constellations Cetus and Aries, sets 10:49 p.m. in the west-northwest. Three planets rise overnight. The first is Jupiter, rising at 1:54 a.m., followed by Saturn at 3:42 a.m., and Venus, the brightest, and last to rises, appears at 4:39 a.m., over the east-southeastern horizon.

The nights close to the New Moon are best for observing deep sky objects. Go to your favorite dark sky site, and search for the brightest galaxies, star clusters, and nebulae. Our Milky Way is part of 54 galaxies known as the Local Group. It is also part of a larger formation known as the Virgo supercluster. The closest spiral galaxy to the Milky Way is the Andromeda Galaxy, at the distance of 2.5 million light-years. Although Andromeda is the closest spiral galaxy, it is not the closest galaxy. That distinction goes to the Canis Major Dwarf Galaxy. The Canis Major Dwarf Galaxy is 42,000 light-years away from our galactic center, and 25,000 light-years from our solar system. Our solar system is 30,000 light-years away from the galactic center. This dwarf galaxy is in the process of merging with the Milky Way, with 200 to 400 billion of its estimated 1 trillion stars already part of the Milky Way galaxy. The Canis Major Dwarf Galaxy was discovered in 2003 by the Two Micron All-Sky Survey (2MASS), and using the data obtained from 1997 to 2001 observations from the Hopkins Observatory in Arizona. As this dwarf galaxy is being pulled into the Milky Way, it is leaving a long filament of stars behind as it orbits our galaxy. This trail is forming a ring-like structure, known as the Monocerus Ring, which wraps around the Milky Way three times. M79, discovered by Pierre Mechain in 1780, is believed to be a globular cluster absorbed from the Canis Major Dwarf Galaxy. You can find 8th magnitude M79 in the constellation Lepus about 10 to 12 degrees above the southwestern horizon, forming a V with the stars Sirius, in Canis Major, and Rigel, in Orion, above.

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