Yes, three supermoons will grace the night sky on December 3, 2017, January 1, 2018, and January 31, 2018. And for its encore, the January 31st supermoon will feature a total lunar eclipse, with totality viewable from western North America across the Pacific to Eastern Asia.
“The supermoons are a great opportunity for people to start looking at the Moon, not just that once but every chance they have!” says Noah Petro, a research scientist from NASA’s Goddard Space Flight Center. The moon will appear to be 14 percent larger and about 30 percent brighter.
When seeing the supermoon suspended low on the horizon, it appears close enough that you might want to reach out and grab the giant orb, but then you will realize your eyes have deceived you. But it is an amazing celestial event worth taking the time to watch.
The December 3 supermoon
Sunday night’s “Full Cold Moon” is appropriately named because December is the month when winter truly begins in most of the Northern Hemisphere. This full moon is also known as the Long Nights Moon and the Moon before Yule.
It’s also the year’s one and only full supermoon. In other words, it comes close enough to Earth -222,443 miles or 357,987 kilometers – to be called a supermoon. The astrologer Richard Nolle, who is credited with coining the term, defines a supermoon as: “a new or full moon which occurs with the moon at or near (within 90 percent of) its closest approach to Earth in a given orbit.
For those who can’t get outdoors, you can watch Sunday’s supermoon live online here, courtesy of the online astronomy service Slooh or directly from Slooh.com here.
The two supermoons in January
The two full moons in January 2018 also are considered supermoons, based on the definition. However, the second of these three full moon supermoons, in January, most closely coincides with lunar perigee, showcasing the closest and largest supermoon in this series of three.
Basically, the perigee is the point in the moon’s elliptical orbit around the Earth when the moon is closest to the planet. Conversely, the point in the moon’s orbit where it is furthest from the Earth is called the apogee. As a result of the orbit being elliptical, the moon’s distance from Earth varies throughout the year.
Full moon distance (2017 Dec 3 at 15:47 UTC): 357,987 km
Lunar perigee distance (2017 Dec 4 at 8:42 UTC): 357,492 km
Full moon distance (2018 Jan 2 at 2:24 UTC): 356,846 km
Lunar perigee distance (2018 Jan 1 at 21:54 UTC): 356,565 km
Full moon distance (2018 Jan 31 at 13:27 UTC): 360,199 km
Lunar perigee distance (2018 Jan 30 at 9:54 UTC): 358,995 km
The “Must See” encore on January 31
The January 31st supermoon is also called the “Blue Moon,” only because it’s the second full moon in the same month. So while you can get one more look at a supermoon, this one will be extra special because it is paired up with a total lunar eclipse. Usually, the moon’s orbit around Earth is slightly tilted, so it falls a little above or below the shadow of the Earth.
However, about two times a year, the full moon lines up perfectly with the Earth and the sun so that the Earth’s shadow totally blocks the sun’s light, which would normally reflect off the moon. “The lunar eclipse on January 31 will be visible during moonset. Folks in the Eastern United States, where the eclipse will be partial, will have to get up in the morning to see it,” notes Petro. “But it’s another great chance to watch the Moon.”
Because of the way the Earth’s atmosphere bends light, the January 31 supermoon could appear to be a reddish hue. This is why a totally eclipsed moon is sometimes called the “Blood Moon.” “We’re seeing all of the Earth’s sunrises and sunsets at that moment reflected from the surface of the Moon,” says Sarah Noble, a Program Scientist at NASA headquarters.
Bottom line, folks – Way too often, we get so tied up in political, social and other worries too numerous to mention, we forget to take notice of the amazing natural events right before our eyes. So take the time to step outdoors on one of these three nights. You might just see something extraordinary.
