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Astrophotographer Adam (AJ) Smadi caught this image a few hours ago from Washington state. A thin crescent Moon, sunlight illuminating the rugged lunar surface. And 2,400 times farther away—and on the other side of the Sun—mighty Jupiter, and its moons Io (left) and Ganymede (right).

See the image on Instagram here: www.instagram.com/aj.smadi/p/D... I verified the position of each of these four elements (the Moon, Jupiter, Io, and Ganymede) with NASA's Eyes on the Solar System. The positions, lighting, and phases all check out. Every indication is that this is real.

Image credit: AJ Smadi (www.instagram.com/aj.smadi/)

Seems like a fitting image on the 60th anniversary of Star Trek.

Your first sentence confused me, but your second sentence clarified, sort of. It doesn't matter which side of the sun Jupiter is on, it's always full. The only planets that go through phases as viewed from earth are Mercury and Venus. If you're on Mars, the earth has phases too.

Apparently an Earth phase cycle as viewed from Mars would be a leisurely 780 days. I’d love to see those photos one day.

Mercury is a planet.

I wonder if we're close enough to Mars to get a partial crescent when we're 90 degrees ahead or behind? I reckon we'd never see less than a half but I haven't got a clue how to check the math on that.

Mars has a bit of a phase. It gets down to 89% Illumination from our perspective.

True. I overgeneralized a bit. Obviously the moon still has a phase even when it's farther from the sun than the earth. It depends on the relative distance and angle to the light source. Even Jupiter has a "phase" but it's probably 99.9999% illuminated.

um, would you have bandwidth to post a little sketch illustrating this? I can't quite wrap my head around it. (Sorry if this is very presumptuous).

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