Skywatch Line for Wednesday, January 13th, and Thursday, January 14th, 2021

This is the Dudley Observatory Skywatch Line for Wednesday, January 13th, and Thursday, January 14th, written by Louis Suarato.

The 0.6% illuminated, waxing crescent Moon sets at 5:23 p.m., Wednesday. Thursday night, a binocular challenge will be to see the 3% illuminated crescent Moon with Mercury over the west-southwestern horizon before they set around 5:35. Mercury will be about 7 degrees to the lower right of the Moon. At 6:43 p.m., Mars can be found about 60 degrees above the Southern horizon. You’ll require binoculars to see the planet Uranus about 8 degrees to Mars’ lower left. When you are viewing Uranus, you are observing a planet approximately 1.7 billion miles from Earth.

At 6:23 p.m., Sirius, in the constellation Canis Major, and the brightest star in the sky, rises over the east-southeastern horizon. Sirius, also known as Alpha Canis Majoris, is a binary star comprised of Sirius A, a main sequence star, and Sirius B, a faint white dwarf star. The two stars combined shine at magnitude -1.45. Sirius’ brightness is a factor of its luminosity, and its proximity to our solar system. Sirius is 25 times more luminous than our Sun, and is only 6.6 light-years away, making it one of the closest neighboring stars. A small telescope, such as a 4 inch refractor, can split the two stars of Sirius.

As Sirius climbs the sky, and clears the atmospheric interference, look 10 to 15 degrees to southeast to view no less than 10 open star clusters. The open clusters include M46 and M47, and the Heart-Shaped and Caroline Clusters. Open star clusters are relatively young stars formed near the plane of the Milky Way. M46 and M47 are about 1 degree apart, and about 5,400 light-years away. M46 contains a few hundred stars estimated to be 300 million years old. M47 contains about 50 stars aged 80 million years. Look within M46 for the colorful glow of gas which is the planetary nebula, NGC 2438, a billion year-old star in its final phase.

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