Night owls and astronomy enthusiasts will want to look up in the skies late tonight in Colorado, and hope there aren’t too many clouds to see the moon.
For the first time in three years there will be a total lunar eclipse, which will give the moon a blood-red glow.
Bruce Bookout, professor of astronomy at Pikes Peak State College and a member of the Colorado Springs Astronomical Society, talked with CPR’s Colorado Today podcast about what to expect.
This transcript has been edited for clarity and length.
Colorado Today: What is a lunar eclipse?
Bruce Bookout: A lunar eclipse is simply when the moon has fallen into the path of the Earth's shadow.
CT: How common are these?
BB: They happen periodically. About every six months we will get eclipses around the world, but because of the odd geometries of the Earth's orbit and the moon's orbit, [they don’t always look like this]. This particular lunar eclipse is in an alignment where we are hitting the moon's orbit where it intersects with the Earth's orbit around the sun, and it's in a line called the line of nodes. When we align on the nodes and there's a full moon, boom, we get [the red moon].
CT: Why does the moon appear red, instead of being blacked out, for example?
BB: You'd think falling into the shadow of something, it would go completely black. What's really happening is, as we fall into the darkest part of our shadow, we're actually catching light that has been bent by the Earth's atmosphere.
It's bent because of a property called refraction, like a setting sun does, where as it bends, it strips out all the blues and yellows and greens and what penetrates through and gets slightly bent back onto the moon is this red light. So the full lunar eclipse appears red, or if you want to be dramatic, ‘blood red’.
CT: Do we need a telescope to see it?
BB: No, not really. A pair of binoculars is probably the most powerful thing you’d want if you want to see some pretty details. But the naked eye does very, very well to be able to take a look at it.
The hard part is this one is occurring later in the evening [around 1 a.m.].
