The sun, moon and Earth line up every month. That, in itself, is nothing extraordinary.
For most of those months, the moon’s orbit is at a slight angle from the Earth’s shadow.
"The moon is either too high or too low, and we just have a normal full moon," said Andy Veh, a physics professor at Kenai Peninsula College. "But every six months, every six full moons, the moon actually orbits through the moon’s shadow. And that’s when we have a lunar eclipse.”
There’s going to be a total lunar eclipse late Tuesday night ― or, early Wednesday morning ― which will be visible in much of Alaska. Those who can stay awake until 3:18 a.m., when the eclipse peaks in Kenai, will see a red-tinted full moon just over the horizon.
Lunar eclipses happen every six months. But observers from any given spot on Earth will see them more infrequently, depending on whether they’re experiencing night or day at the time.
The moon will appear slightly red during this week’s eclipse, because the Earth’s atmosphere scatters, or refracts, the light coming through from the sun. Red is the least refracted of all the colors of light, which is why it’s the one we can see.
As is the case with the aurora, the color comes out more vibrantly in photos. Also, like the aurora, it’s more a cool phenomenon to witness than anything else.
But Veh said there did used to be a greater significance to the lunar eclipse.
"The shadow on the moon is somewhat round. It’s not a straight line," he said. "So way back when — I’m talking 2,000, 3,000 years ago, when people really didn’t know how the Earth was shaped — during the lunar eclipse, they saw it. They saw a round shadow of the Earth on the moon during the lunar eclipse, and concluded from that, we must be living on a round Earth.”
It’s a treat to have a visible astronomical event during the summer. The lack of darkness makes it so there’s usually not much to see.
"In the summer, it's not much worth doing astronomy," Veh said. "Because you have like two hours and kind of twilight going out, and you’re not going to see much.”
Still, this viewing is not without its obstacles.
The moon will be low to the horizon. Veh recommends getting somewhere you can see clearly, like a beach, and looking south.
"If you go to your backyard, it’s actually not going to work," Veh said. "Because you have trees in the way.”
The partial lunar eclipse starts close to 2 a.m. and ends near 5 a.m. on May 26. Note that’s after midnight Tuesday, in the early hours of Wednesday.
Peak eclipse ― when the moon is most entirely covered ― will start around 3:11 a.m. and end at 3:25 a.m.
Unlike the solar eclipse, you don’t need any sort of eye protection to watch this one.
For exact timing on this eclipse, click here.
