New Year, New Sky: A January Skywatching Guide
The New Year brings a great meteor shower, a rarely visible planet, a "blue moon," and a total lunar eclipse. Here are a few things skywatchers should be on the lookout for as they begin 2018.
JANUARY 1: VISIBLE MERCURY & WOLF SUPERMOON
Just before sunrise on New Year's Day, Mercury will be visible in the sky. Because of its proximity to the Sun, you can only see the planet on a handful of days every year—when Mercury reaches “greatest elongation”—and even then, you only have a narrow window of opportunity to see it. (For reference: In New York State, the magic hours are between roughly 5:30 a.m. and 6:00 a.m. Mercury will peak in the southeast a mere 10 degrees over the horizon. The times and maximum height over the horizon will vary based on your location. Check for your location here.) If you're pulling a New Year all-nighter anyway, be sure to make the effort.
Finding the southeast is easy. (Worst-case scenario, use the compass app in your phone.) But how do you calculate 10 degrees over the horizon? The easiest way is to hold your thumb out sideways at arm's length. The thickness of your thumb is about two degrees. A clenched fist, upright, is about 10 degrees. Hold the bottom of your fist at the horizon; the top of it will reveal an approximation of where Mercury should be.
That's not the only sky event on January 1. We'll also see the first full moon of 2018. It will be a “supermoon”—that is, it will be full while closest to Earth in its elliptical orbit. (Unless you are a devoted Moon watcher, you are unlikely to notice whether or not the Moon is a few percentage points larger than normal, so don't get too caught up in that.) According to the Old Farmer's Almanac, Native Americans called this first full moon in January the Wolf Moon, because winter has been in full swing for a while now, and wolves are hungry. There's a little extra longing in those customary howls.
JANUARY 3–4: QUADRANTIDS METEOR SHOWER
On January 3 at around 11:00 p.m., you can celebrate J.R.R. Tolkien's birthday (and mine) by finding an area of little light pollution, laying out a blanket, turning off your phone, opening a bottle of wine, and letting your eyes adjust to the darkness. Just before midnight, your eyes should be good and ready to enjoy the first major meteor shower of 2018: the Quadrantids. On a good year, you'll be able to catch around 70 meteors per hour. This, however, will not be a good year, because of an almost fully illuminated moon which will wash out the night sky. All is not lost, however: If the sky is clear and you've found a nice remote area, you're sure to see something through the predawn hours of January 4.
The Quadrantids are particularly interesting for two reasons: 1. They are named for Quadrans Muralis, a constellation “drawn” by an 18th-century French astronomer, but which fell out of favor in the late 1800s and does not formally exist today, according to the International Astronomical Union; and 2. The meteor shower is produced by 2003 EH1, a near-Earth asteroid that is believed to be an extinct comet. (With no volatiles left to sublimate and give it that distinct comet tail, or coma, the comet essentially becomes a hunk of space rock. We still love it, but it's no Halley.)
JANUARY 31: BLUE SUPERMOON ECLIPSE
Every month begins or ends with a full moon, more or less. The lunar phases are where we get the word "month" in the first place. Every so often, the lunar cycle so aligns as to give us two full moons in one month. This second full moon is called a "blue moon" (as in: "once in a … "). There's no cosmic magic about it, though it is a lovely way to acknowledge the beauty of celestial mechanics. The blue moon on January 31 will be a particularly good showing, as it is a supermoon, and in the western United States, across the Pacific, and into eastern Asia, there will be a total lunar eclipse! At moonset, the Moon will cross through the darkest part of the Earth's shadow and turn a reddish color. No telescopes or special protective glasses will be needed to enjoy this. (The eastern United States will experience a partial lunar eclipse, whereupon a part of the moon will darken. It's better than nothing!)
If your January skywatching is ruined with rain and alarm clocks that didn't go off, don't lose hope. Next month promises a minor meteor shower, a "black moon," and the always-romantic Valentine's Day star.
Editor's Note: This post has been updated.