Three moon cycles will line up over parts of the United States on Jan. 31 for an event so rare that it last occurred before the Civil War. A supermoon, a total lunar eclipse, and a blue moon converge for a celestial view that will produce a bright, red moon, according to Embry-Riddle Aeronautical University astronomy professor Jason Aufdenberg.
“It’s just a wonder to behold,” he said in a Jan. 24 news release. “We’ve had a lot of supermoons and we’ve had lunar eclipses, but it’s rare that it also happens to be a blue moon. All three of these cycles lining up is what makes this unusual.”
The news release noted that a supermoon "can happen four to six times a year" and "occurs when the full moon is at the closest point of its orbit around Earth." A lunar eclipse "occurs at least twice a year," and "happens when the Earth passes directly between the sun and the moon" and casts the Earth’s shadow on the moon. A blue moon refers to the occurrence of two full moons in one month and is seen every two years, eight months, and 18 days.
Aufdenberg’s research found that a supermoon, a blue moon, and a total lunar eclipse were visible from the eastern United States on May 31, 1844, and were visible from the entire United States more than five hundred years prior, on May 31, 1341.
Skygazers should get their cameras ready to document the phenomenon, called a "blue blood supermoon" or "super blue blood moon," although it will actually appear to be red. Aufdenberg explained the fiery hue is a result of “all the sunsets of the world” falling on the moon during the brief celestial window.
“For the (continental) U.S., the viewing will be best in the West,” NASA lunar blogger Gordon Johnston advised in a Jan. 18 news release. “Set your alarm early and go out and take a look.” He said skygazers along the West Coast, Alaska, or Hawaii “will have a spectacular view of totality from start to finish” because it will be visible before sunrise.
Viewing will also be favorable for those in the Central time zone, “since the action begins when the Moon is higher in the western sky.” At 4:51 a.m. "the penumbra—or lighter part of Earth’s shadow—will touch the Moon" and "the Earth's reddish shadow will be clearly noticeable on the Moon" by about 6:15 a.m. He said the best window for Midwestern viewers will be from about 6:15 to 6:30 a.m.
Johnston explained that lunar eclipse viewing "will be more challenging in the Eastern time zone" because it will be 5:51 a.m. when the moon sets in the western sky while the sky gets brighter to the east. He added that the "best opportunity if you live in the East is to head outside about 6:45 a.m. and get to a high place to watch the start of the eclipse—make sure you have a clear line of sight to the horizon in the west-northwest, opposite from where the Sun will rise.”
An Aug. 21 total solar eclipse brought thousands of aviation and astronomy enthusiasts together for viewing parties that popped up at airports across the United States.