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12/29/2021 – Ephemeris – Let’s search for the naked-eye planets for this week

December 29, 2021

This is Bob Moler with Ephemeris for Wednesday, December 29th. Today the Sun will be up for 8 hours and 50 minutes, setting at 5:10, and it will rise tomorrow at 8:19. The Moon, halfway from last quarter to new, will rise at 4:37 tomorrow morning.

Let’s search for the naked-eye planets for this week. Venus will be visible in the southwestern evening twilight by 6:00 tonight. It’s a crescent in telescopes, and even binoculars now. It is moving closer to us, and now appears larger than Jupiter in telescopes. Venus will set at 6:35 pm, 31 minutes earlier than it set a week ago, which means that the Sun is catching up with it faster and faster. It has only 10 days left in the evening sky, Mercury might be spotted just below left of Venus. By 5:45 pm, both Jupiter and Saturn should be able to be spotted in the southwestern sky. Saturn will be dimmer, and to its lower right, halfway between Jupiter and Venus. Saturn will set at 7:35 pm, with Jupiter setting later at 9:31 pm.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.


Evening planets at 6 pm 12/29/21

The evening planets in the southwest at 6 pm tonight, December 29, 2021. Created using Stellarium.

Mars and the Moon in the southeast at 7 am

Mars and the Moon in the southeast at 7 am, tomorrow morning, December 30, 2021. Note that Mars is near its rival in color, the red giant star Antares in Scorpius the scorpion. Sometimes Mars is dimmer than Antares, sometime it’s brighter. It depends on Mars’s distance. Currently, it’s quite far away, at 218 million miles (352 million kilometers). The Moon is shown at twice its actual size to better show its thin crescent phase. Created using Stellarium.

Telescopic views of naked-eye planets12/29/2021

Telescopic views of the bright planets and their brighter moons (north up) as they would be seen in a small telescope, with the same magnification, this evening at 7 pm, December 29, 2021. Apparent diameters: Venus, 59.89″, 3.7% illuminated; Saturn 15.49″, its rings 36.09″; Jupiter, 35.57″. Mercury is not shown, its apparent diameter is 5.68″ and is 82.4% illuminated. Mars also is not shown, its apparent diameter is 3.99″. The ” symbol means seconds of arc (1/3600th of a degree.) Created using Cartes du Ciel (Sky Charts).

In the above chart, I don’t show any planet that’s less than 10 seconds of arc in diameter due to the limitations of scale of what I can show that would be appropriate or small telescopes.

Planets and the Moon on a single night

The naked-eye planets and the Moon at sunset and sunrise on a single night, starting with sunset on the right on December 29, 2021. The night ends on the left with sunrise on the 30th. Click on the image to enlarge it. Created using my LookingUp program.

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