When the Moon Met Mars

Bad Astronomy
The entire universe in blog form
July 6 2014 7:30 AM

When the Moon Met Mars

Last night (July 5, 2014), the geometry of the heavens swept the Moon past Mars in the sky. This happens every month, but last night the fleeting encounter was closer than most. From my location in Boulder, Colorado, they got a mere 10 arcminutes apart; about one-third the size of the Moon itself.

The closest passage was around 7 p.m. local time for me, with the Sun still up. However, that didn’t deter me—I could easily see Mars through my telescope (it was easy to spot in binoculars as well). So while they were close together I set my ‘scope up, attached my camera, and took about 200 pictures. Of those a few came out well, and I think this one is the best:

Moon and Mars
You can see Mars near the top of the image. Click to appulsenate.

Photo by Phil Plait, used by permission

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How cool is that? It might be hard to see, but in the full resolution image Mars is clearly red, and is also clearly not full, that is, a complete disk. Like the Moon, Mars has phases, but because it orbits outside the Earth’s orbit from the Sun we never see it as a thin crescent (it would need to get between the Earth and the Sun for that, which is thankfully not possible). But it can be gibbous, and in fact last night it was about 87 percent full. I think the phase is exaggerated in my photo possibly due to the focus, but the truth is even by eye it wasn’t full.

And I figured what the heck—after spending so much time getting the focus right, why not get a big ol’ shot of the Moon?

Moon
Hard to believe that's nearly 400,000 km away. Click to embiggen.

Photo by Phil Plait

You know what? Our skies are very, very pretty. It gives me indescribable joy to go out and appreciate that beauty, to try to capture it, and most of all to share it with you.

Because it’s a FAQ: I have a Celestron C8-SGT XLT (an 8” Schmidt Cassegrain), and my camera is a Canon T4i.

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

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