Comet, Planets, and Eclipse in Winter Sky

Closing Out 2018

Comets are notoriously fickle, so predicting the brightness of an approaching celestial interloper can be a risky bet. Nonetheless, follow Comet 46P/Wirtanen, a recurring visitor that is marking the end of 2018 as a possible naked-eye apparition. More realistically, though, look in binoculars for the fuzzy blur. The comet's changing location against the background stars is also shown on the interactive map at https://www.timeanddate.com/astronomy/night/usa/south-bend.

On the night of December 13-14 the Geminid meteor show peaks near the same chunk of sky that the comet traverses. On December 15, the comet is at closest approach to earth and will be well located for viewing in the constellation of Taurus, just above the prominent winter constellation Orion to the south. Keep looking for the comet on subsequent clear nights, too.

At morning twilight on December 21 you can find two planets in conjunction in the odd constellation Ophiuchus. The serpent-bearer is actually the 13th constellation of the zodiac these days, even though it's lesser known, because the ecliptic (the line along which the planets appear) cuts through the edge of its boundaries. While many people know the standard constellations of the zodiac (e.g., Gemini, Leo, Virgo, etc.), Ophiuchus is barely a member of that elite club. And on December 21, Jupiter and Mercury pass each other against the background stars within Ophiuchus.

As you wait for December 21, Venus is blazing in the morning sky, with Mercury lower to its left. Each morning at the same time Mercury appears to move slightly eastward, meeting the king of the planets, Jupiter, on the solstice and then sinking out of sight in subsequent days.

Winter solstice occurs December 21, which is a good time to start (or retrieve) a solargraph. When you include the seasonal extremes, the pinhole camera captures the entire path of the sun between the solstices, from a low arc in the winter sky to a high arc in the summer sky.

New Year 2019

January 1 begins with a morning twilight alignment of the moon, Venus, Jupiter, and Mercury. The size of the planets in the illustration are not to scale; rather, the size depicts the relative brightness of the planets. Hence, the moon appears "less bright" than Venus in the illustration, with Venus dominating the apparent brightness compared even to Jupiter. By January, Mercury has nearly disappeared in the morning twilight.

Early in the the new year is an easy-to-observe treat. On the night of January 20-21 a total lunar eclipse is visible from South Bend, IN, in its entirety from start to finish. See the animation at https://www.timeanddate.com/eclipse/in/usa/south-bend for local circumstances around South Bend, IN, or adjust it for your location. It's an excellent depiction showing times of key eclipse stages, with the key local moments being 10:34 pm when the partial eclipse becomes obvious and from 11:41 pm to 12:43 am when the moon is wholly within the shadow of earth--totality.

9:36 pm Penumbral Eclipse begins; faint outer shadow is harder to discern

10:34 pm Umbral Eclipse begins; at the "public start" it's more obvious that the eclipse is underway

11:41 pm Total Eclipse begins; moon is reddish while totally in earth's shadow

12:12 am Maximum eclipse; essentially the midpoint of the spectacle

12:43 am Total Eclipse ends; brighter moon edge appears

1:50 am Umbral Eclipse ends; I start packing up gear, for the outer shadow is hard to notice

2:48 am Penumbral Eclipse ends; end of the show

Looking forward, 2019 will mark the 50th anniversary of the Apollo 11 moon landing. Expect more hype as June 20 approaches. Meanwhile, if you're looking for an activity that re-enacts the moon landing, see my blog post Land on the Moon 50 Years Later.

Wishing you clear and dark skies as we begin a new orbit around the sun.

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