MELISSA BLOCK, HOST:
Tonight, everyone in America, where the skies are clear, will be able to experience a rare and beautiful thing - a super wolf blood moon in total lunar eclipse. Joining us to explain what that is and when you can see it is Pamela Gay. She's an astronomer with the Planetary Science Institute and co-host of the aptly named podcast Astronomy Cast. Pamela Gay, welcome to the program.
PAMELA GAY: Well, thank you so much for having me.
BLOCK: So a super wolf blood moon. Let's break that down into its individual parts - first, the supermoon part.
GAY: The supermoon just means the moon is closer than it is on other days during the month. As it goes around the Earth, sometimes, the moon's a little bit closer. Sometimes, it's a little bit further. And when it's a supermoon, it's at its closest point. It appears 14 percent larger than when it's furthest away. And this closeness makes it 30 percent brighter when it's full like it is this month.
BLOCK: OK. So this will be a supermoon, also, a wolf moon.
GAY: That is less interesting. We get a wolf moon every single January. It's just what we call the full moon of January.
BLOCK: OK. So supermoon, wolf moon and, also, tonight a blood moon.
GAY: Yes. With an eclipse, our moon passes into the Earth's shadow, which is something it doesn't do every single orbit. Usually, it's above the shadow, below the shadow, and we see a full moon. When that full moon, instead, passes through the Earth's shadow, it doesn't go completely dark. Instead, light from the sun gets bent around the Earth. It gets refracted around by our own atmosphere. And that atmosphere tends to scatter out a lot of the blue light leaving the red light to give us this blood red moon for the same reasons that our sunset is red.
BLOCK: Wow. It sounds incredible, and it will be visible if - assuming the skies are clear, visible all across the United States.
GAY: All across North and South America. It is really one of those great shared experiences for everyone on our hemisphere.
BLOCK: When are people going to be able to see the super wolf blood moon tonight?
GAY: So the very first moments of the eclipse are going to be at 10:10 p.m. Eastern Time. Totality will start at 11:41 p.m. Eastern with the middle of totality being at 12:12 a.m. as we go into Monday.
BLOCK: That's astronomer Pamela Gay of the Planetary Science Institute in Tucson. She hosts the Astronomy Cast podcast. Thanks so much for talking to us.
GAY: My pleasure. Transcript provided by NPR, Copyright NPR.