Last Quarter, Regulus, and the direction ahead

There is a grouping – two bright objects plus a geometrical abstraction – to be seen in the night between Sunday and Monday, November 20/21: the Moon, the star Regulus, and the Earth’s direction of travel.

Sky scebe 2016 Novenber 21 in earlymorning

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Cascade

Tomorrow morning, you can see the Moon about to eat Mars.

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But, the morning after, Mars will still be there, as the Moon continues on its way down the row of planets in the morning sky.

It passes Mars very closely, then Venus less closely, then Saturn rather widely. The separations (between the Moon’s center, as seen from the Earth’s center) and the planets are 0.13, 1.1, and 3.1 degrees.

The Mars encounter happens at Dec. 6, 3 hours Universal Time, thus for Europe and America in deep night between Dec. 5 and 6. So on the morning of Dec. 5 we see the Moon before it reaches Mars, and on the next morning, after. The Mars conjunction is so close that the Moon occults (covers) the planet as seen across a central band of the Earth. Because of the timing in Earth’s rotation, the only region favorably placed to see the occultation in a dark sky is eastern Africa. Skilled Australian observers may, in their afternoon sky, be able to pick up the bright pinpoint of Mars just before it hits the scimitar-like curve of the Moon’s advancing edge.

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Detail from the “Occultations” section of Astronomical Calendar 2015.

Venus, too, will be occulted, on Dec. 7 at 17 UT, which means the occultation track passes over North America, but in daylight.

By the time the Moon reaches Saturn, on Dec. 10 at 15 UT, they are impractically low to the sunrise horixon, only about 10 degrees from the Sun, the Moon extremely thin because it will be at its New position the next day. 11.

Comet C/2013 US10 Catalina, now appearing near to Venus, is, we hope, in its climb toward perceptibility with the naked eye. It is also climbing northward, to pass near Arcturus on January 1.