Lunar triple sunset

Lunar triple sunset

Lunar triple sunset

Bad Astronomy
The entire universe in blog form
July 29 2010 7:00 AM

Lunar triple sunset

I never get tired of the stunning pictures being sent to Earth from the Lunar Reconnaissance Orbiter. This one is particularly cool:


Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  


It's a little weird, isn't it? What you're seeing is sunset over some mountains on the Moon, with only the peaks popping up into the sunlight. It might help to pull back a bit:


[Click to embiggen.]

That's a little better. You can see the long shadows of the two mountains on the hills farther back, giving the image a bit of context and relief.


But you're still missing the coolest part. Ready? Here's the entire shot: bhabha_sunset3

Whoa! Getting the picture now? Those three mountains are actually the central peaks of the crater Bhabha, a 64 kilometer (40 mile) wide impact scar on the far side of the Moon. With really big impacts, the shock waves bounce around inside the crater bowl, making the rock flow like a fluid. The rock flows outward, then sloshes back inward, splashing up to form peaks. Usually there's only one, but Bhaba has three.

This shot is from the west, facing east. It was taken just minutes before the Sun set over the peaks, throwing them into two weeks of darkness -- remember, the far side of the Moon gets light just like the near side; when we see a thin crescent Moon that means the Sun is shining down on the other side, just like day on one side of the Earth means night on the other.

This picture is a vivid reminder that the Moon is a world in its own right. Eventually, I hope, people will once again get to see views like this by simply looking out the window. Until that time, LRO will provide us with these amazing pictures.

Image credit: NASA/GSFC/Arizona State University