Meteor Showers, a Supermoon, and the Solstice: A Guide to the December Night Sky

Thomas Coex/AFP/Getty Images
Thomas Coex/AFP/Getty Images

This has been a fantastic year for sky watching. Eclipses in particular had their day in the Sun, with celestial objects blotting each other out as if in competition. There was a penumbral lunar eclipse and an annular solar eclipse in February, and then in August, a partial lunar eclipse was followed up by a mind-blowing total solar eclipse. If you missed any or all of those events, don't lose heart: they will happen again and again and again, in your lifetime and beyond. Celestial mechanics guarantee it. The year isn't over yet, though, and December has a few wonderful events up its sleeve. Here are four things you should be on the lookout for in the skies above.

DECEMBER 3: THE ONLY SUPERMOON OF 2017

I know, supermoons are so 2016. There were six that year, if you don't recall. (I do, because I had to think of new things to write about every single one of them.) This year has been a bit less active in terms of super lunar events, with a total of zero must-see giant moons for your viewing pleasure. That changes on December 3 with the first and only supermoon of the year, and it has a great name at that: the Full Cold Supermoon. The "cold" part of the name, according to the Old Farmers Almanac, derives from Native American tradition. (They weren't being creative here; it's just really cold in December.) The "super" part is because the Moon will be at perigee—that is, the closest to Earth it's going to get in its orbit. The moon's orbit is not a perfect circle, meaning it sometimes appears larger in the sky than others.

Expect a moon that's about 14 percent larger than when it is at apogee (farthest from Earth), though, unless you are an obsessive moonwatcher, the larger size will be nearly imperceptible. My advice is to point at the moon when your friends are around and say something like, “Hey, check that out. I think that's a supermoon! You might not notice a difference, but I sure do. Compared to the moon at apogee, it's huge! Why, it's got to be 14 percent larger, at least. Wow!” Then change the subject quickly, because nobody likes a know-it-all.

DECEMBER 13–14: MORE THAN 100 METEORS PER HOUR

The Geminid meteor shower is considered the best meteor shower of the year, and it peaks after midnight between December 13 and 14. If you are in an area of low (or no) light pollution, and if you give your eyes an hour to adjust to total darkness, and if the weather is good (a lot of "ifs," but worth it if you can arrange things), you can expect to see more than 100 meteors per hour. Geminid meteors are a result of the Earth colliding into the debris field of the asteroid Phaethon, an unusual "rock comet" that leaves behind dust- and sand-sized particles as it circles the Sun. A speck of dust might not seem like much, but when the atmosphere of a 13,170,000,000,000,000,000,000,000-pound planet plows into it at tens of thousands of miles per hour, it is vaporized in a beautiful streak of light.

As if that isn't cool enough, on December 16, Phaethon itself will make its closest approach to Earth in 43 years! Yes, the Minor Planet Center officially considers Phaethon to be a "potentially hazardous object," but before you dust off your Y2K prepper supplies, know that the asteroid will be 27 times farther away than the Moon generally is from the Earth. Sadly, it is unlikely to affect the meteor shower in any measurable way.

DECEMBER 21: THE WINTER SOLSTICE

December 21 will play host to the longest night of the year. Why? Because the Earth's axis is tilted by about 23.5 degrees, and as we orbit the Sun, different latitudes are in direct sunlight. Presently, the southern hemisphere is “closer” to the Sun than the northern. On the 21st, the Tropic of Capricorn (latitude -23.5 degrees) will be in the overhead sun and will receive 13 hours, 27 minutes of daylight. The higher in latitude you go from the Tropic of Capricorn, the less daylight that part of the Earth will receive. The equator will get 12 hours of sunlight. The North Pole will get zero seconds of daylight. The Tropic of Cancer will get about 10.5 hours.

We call this the Winter Solstice, and it's when you'll find some of the best parties of the year. That much night, after all, and anything can happen. Starting on the 22nd, the days will begin to get longer in the northern hemisphere, with spring soon to follow.

DECEMBER 22: THE URSID METEOR SHOWER

Just before sunrise on the morning of December 22, as you're stumbling home from that killer Winter Solstice party, look up. Well, first find a spot with low light pollution and give your eyes time to adjust, and then look up. You will be treated to the annual Ursid meteor shower, here to ring out 2017—and not a minute too soon.

The Ursids are no Geminids; at best you'll only catch 10 meteors an hour, but because the Moon will be but a sliver, the natural skies should be nice and dark. Weather not cooperating? Don't worry. You should be able to catch an Ursid or two through December 25. (Note that on the night of the 24th, what you suspect is an Ursid might be a sleigh carrying cargo and an elderly, bearded man. A distinct red hue will help you distinguish the two. One is a shooting star. The other is Rudolph's nose.)

A Rare ‘Full Cold Moon Kiss’ Is Coming This Week—Here’s How to See It

jamesvancouver/iStock via Getty Images
jamesvancouver/iStock via Getty Images

Every year ends with a cold moon—the name given to a full moon that appears in December. The full cold moon that's lighting up skies in 2019 will come with a bonus spectacle for sky-gazers. As Forbes reports, a planetary "kiss" between Saturn and Venus will coincide with the last full moon of the year. Here's what you need to know about the astronomical events.

What is a Full Cold Moon Kiss?

The full moon of each month has a unique nickname associated with the time of year it occurs. A cold moon happens as temperatures drop and winter settles in, hence the name. December's full moon has also been called the long nights moon by some Native American tribes and the moon Before Yule in Europe, according to Travel and Leisure.

This year's moon will be visible the night of December 11 through the morning of December 12. On this same night, the planets Venus and Saturn will appear closer than usual in the night sky. The celestial bodies will be less than 2° apart and share a celestial longitude, a phenomena known as a conjunction or a planetary "kiss."

How to See the Full Cold Moon Kiss

During twilight on Tuesday, December 10, the bright planet Venus and the dimmer planet Saturn will arrive at their closest conjunction, 1.8° apart, above the southwestern horizon. The following evening, they'll be just .01° further away. Stick around the night of Wednesday, December 11 to catch the full cold moon, which reaches peak illumination at 9:12 p.m. on the West Coast and at 12 minutes after midnight on the East Coast.

Not planning on staying up late to see the moon reach its fullest state? Moonrise on December 11 will be just as spectacular. When the moon surfaces around sunset, it will appear larger and more reddish in color in the sky. Meanwhile, Venus's and Saturn's kiss will be visible 180º away.

[h/t Forbes]

First-Ever Map of Titan Reveals That Saturn’s Moon Is a Lot Like Earth

NASA/JPL-Caltech/Univ. Arizona/Univ. Idaho
NASA/JPL-Caltech/Univ. Arizona/Univ. Idaho

If there's any life in this solar system outside Earth, we likely won't find it on Mars or even on another planet. Saturn's moon Titan is the place in our celestial neighborhood that's most similar to our own home, and it's where scientists think we have one of the best chances of discovering life. Now, as Nature reports, newly visualized data shows just how much Titan has in common with Earth.

Between 2004 and 2017, the NASA spacecraft Cassini performed more than 100 fly-bys of Saturn's moon. Titan is unique in that it's the only moon in the solar system with clouds and a dense, weather-forming atmosphere. This has made it hard to study from space, but by flying close to the surface, Cassini was able to capture the landscape in an unprecedented level of detail.

Map of Titan.
The first global geologic map of Titan.
NASA/JPL-Caltech/ASU

NASA's new map of Titan, published in the journal Nature Astronomy, reveals a varied world of mountains, valleys, plains, and sandy dunes that starkly contrast with the desolate wastelands we've seen on neighboring planets. It's also home to seas and lakes, making it the only place in the solar system other than Earth with known bodies of liquid. But instead of water, the pools mottling the moon's surface consist of liquid methane.

Even with its Earth-like geology and atmosphere, chances of finding life on Titan are still slim: Temperatures on the surface average around -300°F. If life does exist there, it's likely limited to microbes in the moon's craters and icy volcanoes.

It will be a while before NASA is able to study Titan up close again: NASA's next drone mission to the body is set for 2034. Until then, scientists have plenty of data recorded by Cassini to teach them more about how the moon formed and continues to change.

[h/t Nature]

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