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


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?

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!  


Justice Ginsburg’s Crucial Dissent in the Texas Voter ID Case

The Jarring Experience of Watching White Americans Speak Frankly About Race

How Facebook’s New Feature Could Come in Handy During a Disaster

The Most Ingenious Teaching Device Ever Invented

Sprawl, Decadence, and Environmental Ruin in Nevada

View From Chicago

You Should Be Able to Sell Your Kidney

Or at least trade it for something.

Space: The Next Generation

An All-Female Mission to Mars

As a NASA guinea pig, I verified that women would be cheaper to launch than men.

Terrorism, Immigration, and Ebola Are Combining Into a Supercluster of Anxiety

The Legal Loophole That Allows Microsoft to Seize Assets and Shut Down Companies

  News & Politics
Oct. 19 2014 1:05 PM Dawn Patrol Justice Ruth Bader Ginsburg’s critically important 5 a.m. wake-up call on voting rights.
Business Insider
Oct. 19 2014 11:40 AM Pot-Infused Halloween Candy Is a Worry in Colorado
Oct. 17 2014 5:26 PM Judge Begrudgingly Strikes Down Wyoming’s Gay Marriage Ban
  Double X
The XX Factor
Oct. 17 2014 4:23 PM A Former FBI Agent On Why It’s So Hard to Prosecute Gamergate Trolls
  Slate Plus
Tv Club
Oct. 20 2014 7:15 AM The Slate Doctor Who Podcast: Episode 9 A spoiler-filled discussion of "Flatline."
Oct. 19 2014 4:33 PM Building Family Relationships in and out of Juvenile Detention Centers
Future Tense
Oct. 17 2014 6:05 PM There Is No Better Use For Drones Than Star Wars Reenactments
  Health & Science
Bad Astronomy
Oct. 20 2014 7:00 AM Gallery: The Red Planet and the Comet
Sports Nut
Oct. 16 2014 2:03 PM Oh What a Relief It Is How the rise of the bullpen has changed baseball.