Dec21-2020-at-Local-Noon-Northern-Winter-Solstice
Northern Winter Solstice (Chris Vaughan, Starry Night Education)
This Week’s Sky: December 14 to 20, 2020

Watch Saturn and Jupiter as they come closer together. The winter solstice starts off next week with the pair’s conjunction.

Monday, December 14 – New Moon and Total Solar Eclipse (at 16:16 GMT)

New Moon and Total Solar Eclipse (Chris Vaughan, Starry Night Education)

Sorry, fellow Canucks — this one’s not for us.

At its new phase, the Moon is travelling between Earth and the Sun. Since sunlight can only reach the far side of the Moon, and the Moon is in the same region of the sky as the sun, the Moon becomes completely hidden from view for about a day. This new Moon will also produce a total solar eclipse visible inside a narrow track from the South Pacific Ocean, across southern South America, and ending at sunset in the South Atlantic Ocean. The areas of partial eclipse encompass about two-thirds of South America and much of the oceans to either side. The Moon’s shadow will first contact Earth at 14:33 GMT in the Pacific Ocean. During the 97 minutes required for the Moon’s umbra to reach landfall on the coast of Chile at 16:00 GMT, the path of totality widens to 90 kilometres. Totality lasts 2 minutes 8 seconds. Greatest eclipse occurs in Argentina at 16:13:29 GMT, with a totality of 2 minutes 10 seconds. The rest of the total eclipse will not see landfall, leaving the Earth at 17:54 GMT just 360 kilometres west of the coast of Namibia. Except during totality, proper solar filters will be required to view this eclipse.

Tuesday, December 15 – Jupiter and Saturn pass Messier 75 (early evening)

Jupiter and Saturn pass Messier 75 (Chris Vaughan, Starry Night Education)

As the gas giant planets prepare for their Great Conjunction on December 21, they will pass close to a magnitude 9.2 globular star cluster designated as Messier 75 (or M75) and NGC 6864. On Tuesday, December 15 and the surrounding evenings, Jupiter and Saturn will sit approximately a finger’s width to the upper right (or 1.25 degrees to the celestial north) of Messier 75 – allowing all three objects to appear together in the field of view of a backyard telescope at low magnification (red circle). To better see the dim, fuzzy cluster, try to view the trio as soon as the sky darkens, when they are higher in the sky. The meet-up will especially favor observers at southerly latitudes.

Wednesday, December 16 – Young Moon below Jupiter and Saturn (after sunset)

Young Moon below Jupiter and Saturn (Chris Vaughan, Starry Night Education)

Look low in the southwestern sky immediately after sunset on Wednesday, December 16, for the young crescent Moon sitting a slim palm’s width below the bright, close-together duo of Jupiter and Saturn. The grouping will make a wonderful photo opportunity when composed with some interesting foreground scenery. The fun continues the following day when…

Thursday, December 17 – Crescent Moon beside Jupiter and Saturn (early evening)

Crescent Moon beside Jupiter and Saturn (Chris Vaughan, Starry Night Education)

The Moon’s monthly visit with the gas giant planets Jupiter and Saturn will continue after sunset on Thursday, December 17. After 24 hours, the Moon’s orbital motion will carry it a fist’s diameter to the upper left (or 9.5 degrees to the celestial southeast) of Jupiter and Saturn. The trio will make a wonderful photo opportunity when composed with some interesting foreground scenery until the two close-together planets set at about 7:15 p.m. local time. The Moon will set 30 minutes after them.

Monday, December 21 – Northern Winter Solstice (at 10:02 GMT)

Northern Winter Solstice (Chris Vaughan, Starry Night Education)

Winter in the Northern Hemisphere will officially commence on Monday, December 21 at 10:02 GMT (or 5:02 a.m. EST and 2:02 a.m. PST). At that time the sun will reach the solstice – its southernmost declination for the year, resulting in the lowest noonday sun, the shortest amount of daylight of the year for the Northern Hemisphere, and the longest amount for the Southern Hemisphere. After the December solstice, the daylight hours will begin to increase for the Northern Hemisphere.

Chris Vaughan is a science writer, geophysicist, astronomer, planetary scientist and an “outreach RASCal.” He writes Astronomy Skylights, and you can follow him on Twitter at @astrogeoguy. He can also bring his Digital Starlab portable inflatable planetarium to your school or other daytime or evening event. Contact him through AstroGeo.ca to tour the universe together.

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