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Lunar eclipse should be starting pretty soon The reddish color is caused by Rayleigh scattering, just like red sunsets and sunrises. |
I'm watching and waiting in Maui :D |
Still white, but it should just start entering the shadow of the Earth in about 5 minutes. It won't be fully in the shadow for a couple of hours though, I think. |
Haven't seen a full lunar eclipse since about 2007, as it always seems to be cloudy here when they happen. But a nice cold front yesterday cleared the skies down here for tonight! |
Look up and to the right of the moon right now and that's Mars. It's near the brightest it will be for another 2.5 years, as it was just in opposition last week. Mars has the longest synodic period (e.g., period as viewed from Earth) of any of the planets. |
Darn clouds are in the way, but windy so maybe they will blow away. |
The shadow has moved a lot in the 20 minutes I have been out here, but we won't see the orange or the red until the moon is completely in our shadow. |
If it wasn't cold as heck out there maybe I'd go outside to watch. It's just not quite as cool watching it through my kitchen window. |
Right now it's covering maybe 1/6 to 1/8 of the full moon. |
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The constellation Scorpius below and to the left of the moon is pretty tonight. |
More than 1/4 coverage now. |
Pretty close to 1/3 coverage now. |
Enough has been eclipsed that it's easy to see the shaded part of the moon now. |
I can see the faintest hues of red in the shaded part of the moon now. |
1/2 way there! Rayleigh scattering is so cool! |
More than 2/3 coverage now! |
A sliver of light left |
The orange color is obvious now. It's caused because the light from the Sun is pretty close to white, and white light is composed of all the colors. Our atmosphere is filled with tiny dust particles that scatter light in random directions when they're small enough; e.g., about 1/2 a micron. The probability of a photon being scattered in a random direction by such a particle is proportional to 1 over the fourth power of the wavelength. So since blue has a shorter wavelength, it gets scattered much more often, leaving long wavelength red light as what we see. So every beam of light from the Sun that hits the shadowed part of the moon passes through the Earth's entire atmosphere first, and all the violet, blue, and green light is scattered away in random directions,leaving only yellow, orange, and red to hit the moon and light it! |
It's the exact same thing that causes red sunsets: when the Sun is low on the horizon the light from it has to pass through a lot more of our atmosphere, so the dust and air particles scatter away most of the violet, blue, and green, leaving yellow, orange, and red mostly. |
Just a tiny bit of the moon still lit outside our shadow. Now is the time to get outside and see this! |
That little sliver just keeps hanging on. But in one minute it will be gone. |
100% coverage now! |
Thanks for the explanation! Wish I had a longer lens, but this 250 telephoto is better than nothing! |
What's crazy, the moon is huge in our sky, at about 1/2 degree angular diameter. But the Andromeda galaxy has 7 time larger diameter: 3.5 degrees. If only our eyes were good enough to see it all. All we can see of it naked eye is the center. Wish I could be here 4 billion years from now to see when it and our galaxy collide. But alas, our Sun will have ballooned into a red giant, boiled away all our water, fried every living thing, and maybe even have swallowed the Earth by then. If only I could go another 200 million years to see Betelgeuse's likely supernova. It's about 6 times closer than the Crab Nebula, so its supernova would be 36 times brighter. And when the crab nebula supernovaed ~1000 years ago it could be seen in the daytime for weeks! |
Definitely redder now than 15 minutes ago! |
How long's it supposed to stay dark? |
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Nice view of Mars 10 degrees or so West too (and maybe 1.5-2 degrees higher). |
I'm going to get to sleep now. What a spectacular sight to see this has been. Hopefully I'll have clear skies in 6 months when it happens again! |
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