Lucky sky-watchers just got a cosmic three-for-one deal, as the second super-size full moon in a month underwent a dramatic total lunar eclipse on January 31. According to eclipse experts, the event marks the first time anyone on Earth has seen this celestial trifecta in 35 years—and the first time it’s been seen in the Americas in 150 years. (See pictures of the rare 2018 lunar eclipse.)
On the 31st, the moon officially reached its full phase at 8:27 a.m. ET (13:27 UT). This is the second full moon to occur in a calendar month, an event commonly referred to as a blue moon. Around the same time, the full moon made an especially close approach to Earth, a phenomenon popularly called a supermoon.
Adding to the space oddity, viewers in some parts of the world also saw a total lunar eclipse on the 31st. When a lunar eclipse hits its peak, the moon’s face can sometimes take on a reddish tone, earning it the moniker of blood moon.
Based on this cosmic combination, the unusual lunar sky show has been dubbed a super blue blood moon. (Check out five places that had good views of the super blue blood moon.)
So, what did sky-watchers actually see?
The nearly full moon reached its closest point to Earth at 6 a.m. ET (11:00 UT) on January 30, when the moon was just under 223,069 miles from our planet. This means the full moon on the 31st appeared about seven percent bigger and 14 percent brighter than usual.
But the most visually impressive part of this lunar show was the total eclipse. Lunar eclipses happen when Earth is between the moon and the sun, so that the moon passes through Earth’s shadow.
Eclipses don't happen every month, because the moon's orbit is tilted with respect to ours, so the lunar orb usually passes above or below Earth's shadow. Our planet's shadow completely engulfs the moon’s face twice a year, on average. (Find out about lunar eclipse myths from around the world.)
Where Will the Eclipse Be Visible?
For this month’s super blue blood moon, the best views were for people on the northern part of North America’s West Coast, as well for viewers across China, Japan, and most of Australia. Observers there witnessed the entire eclipse from beginning to end during the early morning hours of January 31.
The eclipse began when the moon entered the darkest part of Earth's shadow, called the umbra, at 3:48 a.m. PST (11:48 UT). From that point, the umbral shadow spread across the moon’s disk from left to right. Totality began at 4:52 a.m. PST (12:52 UT), when the moon became fully engulfed in the umbral shadow and turned a deep shade of orange-red.
Totality lasted as long as an hour and 12 minutes, depending on your location, with the rest of the visible eclipse ending at 7:11 a.m. PST (15:11 UT).
Observers in parts of western South America, most of North America, India, and eastern Eurasia got to see a partial eclipse, while sky-watchers in large swaths of Africa and South America missed the show.
What Makes the Moon Turn Red?
Although the moon is in shadow during a total eclipse, sunlight shining through Earth's atmosphere gets bent, or refracted, toward the red part of the spectrum and is cast onto the moon's surface. As a result, the lunar disk goes from a dark gray color during the partial phase of the eclipse to a reddish-orange color during totality.
The moon's color during totality can vary considerably depending on the amount of dust in Earth's atmosphere at the time. Active volcanoes spewing tons of ash into the upper atmosphere, for instance, can trigger deep blood-red eclipses.
While no one can predict exactly what color we'll see before each eclipse, based on current activity, astronomers expected that this total eclipse would be a dramatic brilliant orange.
What Happens If I Can’t See Totality?
If you got clouded out or it’s daytime where you are at the time of the eclipse, you could still tune in to the show online via webcasts such as the Virtual Telescope Project and Slooh. And if you missed out this time around, the next total lunar eclipse will arrive on July 27 and will be visible from Asia, Australia, Africa, Europe, and South America, while the next supermoon eclipse will roll around in January 2019.
Editor's Note: This story has been updated to add pictures of the super blue blood moon eclipse.