Twentieth day of a brightening year

It’s January 20, for America a symbolic day in the calendar of each fourth year.  I imagine that around the middle of the day, workers will be swabbing all the furniture in the White House with disinfectant, as we saw them doing a few days ago to the chairs in a medical office, to which we had been invited so as to receive our Pfizer-BionTech coronavirus vaccinations.  It’s a painless and friendly process that will help to protect others beside yourself.  All of which is to say: look up!  Better times are coming.  Jump at the chance, when you get it, to get that jab.  Believe no demented conspiracy theories.

So here is the sky at the conclusion of Inauguration Day.

See the end note about enlarging illustrations.

The Moon comes past Mars and Uranus just as they pass each other.  There may be symbolism to extract from that, but I think not.

The sky scene is drawn for around 10 PM, four hours after sunset, so as to make a more convenient picture by bringing the active region down lower, to about 40° above the horizon.  But on this winter evening you can take a look hours earlier, when Moon and planets are in the south and higher up.

You’ll be able to spot Mars, nearer to the curve of the three Aries stars than to the Moon.  With binoculars you should be able to find Uranus, like a faint star, on the Moonward side of Mars.

The magnitudes of Uranus, Mars, and Moon are 5.8, 0.2, and -10.  This means that Mars is sending us about 170 times more light than Uranus, and the Moon about 12,000 times more than Mars.

Here is the series of events (with times given in Universal Time, and “Moon” referring to the Moon’s center):

January 20, Wednesday
20: Mars closest (1.6°) north of Uranus
21: Moon at First Quarter
January 21, Thursday
10: Moon closest (3.1°) south of Uranus
10: Moon, Mars, and Uranus in tightest grouping (within circle of diameter 4.65°)
11: Moon closest (4.7°) south of Mars
13: Moon at apogee (farthest from Earth, 63.4 Earth-radii)

It all happens at an elongation of 96 to 95° eastward from the Sun.  Notice that it happens near the “antapex of Earth’s way,” the point away from which Earth is moving.  As we hurtle onward, we look back along our orbit at the Moon, crossing outward behind us, and the planets far out beyond the Sun.

January is the month of Janus, who looks backward and forward.

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ILLUSTRATIONS in these posts are made with precision but have to be inserted in another format.  You may be able to enlarge them on your monitor.  One way: right-click, and choose “View image”, then enlarge.  Or choose “Copy image”, then put it on your desktop, then open it.  On an iPad or phone, use the finger gesture that enlarges (spreading with two fingers, or tapping and dragging with three fingers).  Other methods have been suggested, such as dragging the image to the desktop and opening it in other ways.

Sometimes I make improvements or corrections to a post after publishing  it.  If you click on the title, rather than on ‘Read more’, I think you are sure to see the latest version.

This weblog maintains its right to be about astronomy or anything under the sun.