A full Moon rises over California’s Antelope Valley in July 2021. Credit: NASA/Preston Dyches
The next full Moon is a near-total lunar eclipse, the Beaver, Frost/Frosty, or Snow Moon; Kartik Purnima, the full Moon of the Festivals of Karthika Deepam, Karthikai Vilakkidu, Thrikarthika, Loi Krathong, Bon Om Touk, and Tazaungdaing; and Ill (or Il) Poya.
The next full Moon will be early on Friday morning, November 19, 2021, appearing opposite the Sun (in Earth-based longitude) at 3:58 a.m. EST. While this will be on Friday for much of the Earth, it will be Thursday night from Alaska’s time zone westward to the International Date Line in the Pacific Ocean. The Moon will appear full for about three days around this time, from Wednesday night through Saturday morning.
“This should be a good month for skywatching, with
On November 19, 2021 (late evening of the 18th in some time zones), the Moon passes into the shadow of the Earth, creating a partial lunar eclipse so deep that it can reasonably be called almost total. Credit:
An image of comet Leonard (C/2021 A1) taken November 13, 2021, from June Lake in California. Credit & Copyright: Dan E. Bartlett
Comet Leonard
Predicted to be the brightest comet of the year, comet Leonard (C/2021 A1) should be visible with binoculars, and it may become a naked-eye comet!
Discovered last January by G. J. Leonard at the Mount Lemmon Observatory, this comet will pass closest to Earth on December 12, 2021, at 8:54 a.m. EST and reach its closest to the Sun on January 3, 2022, after which it will speed away from the Sun on its way out of our solar system never to return again.
When and how bright a comet will appear is difficult to predict, because we don’t know how much dust and gas the comet will give off (this can vary day-to-day), and this will control how much sunlight is scattered and reflected toward us. Depending on the dust and gas, the modeled peak brightness is expected to be around December 13 or 14, 2021, about 1 to 2 days after its closest to the Earth. If the comet is giving off a lot of dust, this should make the peak brighter due to forward scattering which could shift the peak later toward December14.
Keep an eye on the sky and pay attention to the news, because sometimes comets can surprise us by giving large outbursts of gas and dust as they approach the Sun, and newer observations and better models can improve the predictions of how visible this comet might become.
Around its closest approach to the Earth, this comet will be visible just before dawn and just after dusk. Note that the times and angles I provide are based on a specific location. Although the timing relative to sunset and twilight should not change much for latitudes similar to that of Washington, the specific clock times and time zones may be different for your location. There are a number of online astronomy tools that allow you to enter your location and get information to guide your comet viewing. I recommend using one of these to guide your comet viewing.
For day-by-day predictions for comet Leonard, see the Detailed Daily Guide below.
Geminid Meteor Shower
One of the best and most reliable meteor showers of the year, the Geminids (004 GEM), is predicted to peak around 2 a.m. on December 14, 2021. The best time to look should be after moonset at 2:59 a.m. EST, but before the sky begins to show any sign of dawn (before 6:16 a.m.).
At its peak, under ideal conditions, this meteor shower should show 140 to 150 visible meteors per hour. This meteor shower is expected to be active from December 4 to December 17, with a fairly broad peak, so with good viewing conditions, you have a good chance of seeing some meteors in the mornings before and after the peak. Also, the radiant for this meteor shower is far enough north that those of us in the Northern Hemisphere should be able to see a few meteors that are bright enough to be seen despite interference from moonlight throughout most of the night.
Ideal conditions for viewing these meteors would be if the weather is clear with no clouds or high hazes, the Moon has set but before any sign of dawn interferes, you go to a place far from any light sources or urban light pollution, and you have a clear view of a wide expanse of the sky.
Be sure to give your eyes plenty of time to adapt to the dark. The rod cells in your eyes are more sensitive to low light levels but play little role in color vision. Your color-sensing cone cells are concentrated near the center of your view with more of the rod cells on the edge of your view. Since some meteors are faint, you will tend to see more meteors from the “corner of your eye” (which is why you need a view of a large part of the sky). Your color vision (cone cells) will adapt to darkness in about 10 minutes, but your more sensitive night vision rod cells will continue to improve for an hour or more (with most of the improvement in the first 35 to 45 minutes). The more sensitive your eyes are, the more chance you have of seeing meteors. Even a short exposure to light (from passing car headlights, etc.) will start the adaptation over again (so no turning on a light or your cell phone to check what time it is).
This meteor shower is called the Geminids because the meteors appear to radiate out from the constellation Gemini. The Geminids are relatively slow-moving meteors, entering the Earth’s atmosphere at about 35 kilometers per second (78,000 miles per hour). The Geminids appear to be one of only two annual meteor showers associated with asteroids rather than comets. The dust that causes the Geminids appears to come from the asteroid 3200 Phaethon, which has an eccentric 1.4 year-long orbit that takes it out as far as the main asteroid belt and much closer to the Sun than Mercury. The problem is that it is hard to explain why there is so much dust since we don’t see dust coming off this asteroid now. One possibility is that this asteroid may have shot out gas and dust in the past when it was close to the Sun. There are other possible explanations (and thanks to Bill Cooke at NASA MSFC for providing me with this information a few years ago). There is another asteroid, 2005 UD, that appears to be in a related orbit. It is possible that two asteroids collided with one another, producing 2005 UD, 3200 Phaethon, and the massive amounts of debris that cause the Geminids each year. It is also possible that a larger body in a similar orbit broke apart due to thermal stress or other reasons, producing these two asteroids and the Geminids’ stream.
There will be several other meteor showers during this lunar cycle, each expected to peak at about 15 visible meteors per hour. Given the difficulty urban skywatchers have in seeing these meteors (and how long these Moon Missives are already), I’ve opted not to include descriptions, but if you are in a good place for meteor watching, be sure to look these up!
Evening Sky Highlights
On the evening of Friday, November 19, 2021, the day of the full Moon, as evening twilight ends (at 5:53 p.m. EST), the brightest planet visible will be Venus, appearing 14 degrees above the southwestern horizon. The next brightest planet will be Jupiter, appearing 37 degrees above the southern horizon. The faintest of the visible planets in the sky will be Saturn, appearing to the right of Jupiter at 31 degrees above the south-southwestern horizon. The bright star closest to overhead will be Deneb, appearing 77 degrees above the northwestern horizon. Deneb is about 2,600 light-years from Earth and is the 19th brightest star in our night sky. The bright star Aldebaran will just be rising, appearing about 8 degrees below the full Moon on the east-northeastern horizon.
As the lunar cycle progresses, Jupiter, Saturn, and the background of stars will appear to shift toward the west each evening (although it is actually the Earth that is moving around the Sun toward the east). We are nearing the end of the evenings favorable for Jupiter and Saturn watching. Although both Jupiter and Saturn have been dimming as they move away from the Earth, they have also been shifting toward the west, making them easier to view in the evenings (and friendlier for backyard stargazing, especially if you have young ones with earlier bedtimes). The end of Daylight Savings Time means evening twilight ends earlier, closer to the bedtimes for younger children. At the start of this lunar cycle, Jupiter will appear about 37 degrees above the southern horizon as evening twilight ends at 5:53 p.m.
By the evening of the full Moon after next, Jupiter will appear about 34 degrees above the south-southwestern horizon as evening twilight ends (at 5:52 p.m.). With clear skies and a telescope, you should be able to see Jupiter’s four bright moons, Ganymede, Callisto, Europa, and Io, noticeably shifting positions in the course of an evening. For Saturn, you should be able to see Saturn’s rings as well as Saturn’s largest moon, Titan.
Unlike Jupiter, Saturn, and the background of stars, the bright planet Venus will appear to shift left along the southwestern horizon each evening until November 14, after which it will begin to start to shift back toward the right.
Venus will appear at its highest above the horizon as evening twilight ends around November 28, 2021. Venus will appear to brighten as it shifts closer to the Earth until it reaches its greatest brightness in early December, after which it will decrease in brightness as it continues to shift toward the horizon.
The waxing crescent Moon will appear near Venus on the evening of December 6, Saturn on December 7, and Jupiter on December 8.
December 15 will be the first evening that the planet Mercury will appear above the west-southwestern horizon 30 minutes after sunset (an approximation of when it may start being visible in the glow of dusk).
Comet Leonard will start appearing above the horizon about 30 minutes after sunset on the evening of December 9. It will become brighter and higher in the sky as it approaches its closest to the Earth on December 12 and will reach its predicted maximum brightness one or two evenings after that. For more details see the description above or the Daily Guide below.
By the evening of Saturday, December 18, 2021 (the day of the full Moon after next), as evening twilight ends (at 5:52 p.m. EST), the brightest planet visible will be Venus, appearing 11 degrees above the southwestern horizon. The next brightest planet will be Jupiter, appearing 34 degrees above the south-southwestern horizon. The faintest of the visible planets in the sky will be Saturn, appearing to the right of Jupiter at 21 degrees above the southwestern horizon. The planet Mercury will have already set by the time evening twilight ends, but it may be visible if you have a very clear view of the southwestern horizon from about 30 minutes after sunset (5:18 p.m.) until Mercury sets 9 minutes later. No particularly bright star will appear overhead, with Deneb still the closest at 58 degrees above the west-northwestern horizon.
Morning Sky Highlights
On the morning of November 19, 2021 (the day of the full Moon), as morning twilight begins (at 6:25 a.m. EST), the only visible planet in the sky will be (function(d, s, id){
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