By Linda Weiford, WSU News
PULLMAN, Wash. – Skygazers in the western United States will get a special autumn treat when the full moon rises Sunday, Sept. 27. For the first time in 33 years, a “supermoon” combined with a lunar eclipse will grace the early evening sky, making the moon glow red and appear slightly bigger.
An unusual combination of planetary events will be behind the display, said Washington State University astronomer Michael Allen: “The moon’s dusky red color will probably be what appears most unique about it to the naked eye. The color should be impressive.”
Known informally as a blood moon, the reddish hue is caused when most sunlight is blocked from hitting the moon’s surface as the moon passes through the earth’s shadow during a total lunar eclipse.
Coincidently, the eclipse will occur during a supermoon, when the moon is closer to earth than at any other time of year. This lunar event can make the orb appear 14 percent larger and 30 percent brighter than a typical moon, according to NASA.
“It will be the moon’s closest distance to our planet during its elliptical orbit – what scientists call a perigee moon,” said Allen. At this point, the moon is roughly 26,000 miles closer than it is during its farthest point, he said.
On the night of this celestial show, the moon will rise just after 6:30 p.m. Pacific Standard Time. Look east, just above the horizon, Allen advised: “It will already be in full eclipse.”
Meaning that, under relatively clear skies, people will see something that last happened in 1982 and won’t happen again until 2033. A large blood moon will slide slowly up the sky for more than an hour before returning to its normal color, full and bright as a spotlight.
And unlike many cosmic performances, people won’t have to set their alarms to wake up and see it, said Allen.