Photographer Maik Thomas posted this time lapse video on Google+, and it made me chuckle. The bright object is the Moon, and as it sets it turns red, looking like a missile from space curving right into a church.

I love the star trails effect. It’s just a way of adding the individual frames together to show motion, but it does give the video an oddly other-world feel to it. And in this case it really makes the Moon look like some sort of re-entering rocket!

This is so cool: NASA’s twin GRAIL spacecraft (now named Ebb and Flow) have cameras on board to take images of the lunar surface, and an animation has been put together of Ebb’s view of the Moon’s far side!

Pretty neat. I love the wide-angle view; the individual images were taken while Ebb was still over a thousand kilometers from the Moon. The huge circular feature you can see on the right 30 seconds into the video is Orientale Basin, an impact so huge it must’ve lit up the solar system a few billion years ago. That basin is nearly 1000 km (600 miles) across! See the LRO image below for a clearer view, and click it for more info.

I’m really looking forward to seeing what will be done with these cameras. As Principal Investigator Maria Zuber explains in the video, they were installed specifically for educational purposes, and kids all over America will get a chance to examine the data. I love this idea, since it means these children will be invested in the project itself, and remember it for their whole lives. It’s a fantastic idea.

Image credit: NASA/GSFC/Arizona State University

Thanks to astronaut Ron Garan on Google+, I was alerted to some amazing footage of the Moon setting as seen by astronauts on board the International Space Station. I uploaded it to YouTube and added some comments to show you something really cool…

[Set it to high-def and make it full screen!]

Astonishing, isn’t it? As the Moon sets, you’re seeing it through thicker and thicker air. The air acts like a lens, bending the light upward. The part of the Moon nearer the Earth’s limb gets bent up more, so the Moon looks like it’s getting flattened. Watch it again; the top of the Moon doesn’t appear to be affected much. It looks more like the bottom slows down and the top pushes into it. You can read about this effect in more detail in an earlier blog post.

Weirdly, as I watched the video, it looked very much like the whole Moon was shrinking as it set, as if it were receding rapidly. When I saw that I knew intuitively that couldn’t be real; the ISS is only moving a few thousand kilometers over the time this whole video was taken (about ten minutes), not nearly enough to see that big a change in the size of the Moon. It’s 400,000 kilometers away, after all! So I measured the size of the Moon on the screen, and incredibly the width doesn’t change. Do you see it appear to shrink too? It’s an illusion!

Funny how our brain interprets such things. As if seeing a gigantic rock moving through the sky while perched on board a football-field sized satellite moving at 30,000 km/hr isn’t weird enough!

Credit: Image Science and Analysis Laboratory, NASA-Johnson Space Center. "The Gateway to Astronaut Photography of Earth".

Mynd you, Møøn bites Kan be pretti nasti…

Today, NASA successfully put a new mission into lunar orbit: GRAIL, for Gravity Recovery and Interior Laboratory. Great acronym, weird name, right? What this mission will do is map the gravity field of the Moon, and use that to probe the interior composition. The basic idea isn’t all that complicated: fly a probe around the Moon. If it goes above a region where the density is higher, there will be a slightly stronger gravitational pull, and the spacecraft will accelerate a bit. By carefully measuring the spacecraft position and velocity, you can make the lunar gravity map.

In detail, that’s a bit tougher! What NASA has done is launch two probes, GRAIL-A and GRAIL-B, that will fly in the same orbit, one behind the other^*. They’ll stay in constant communication, sending radio pulses to each other. The timing of these pulses allows an extremely accurate determination of their separation: their distance will be known to an accuracy of about a micron: that’s a hundredth the width of a human hair, or the size of a red blood cell!

So how does that help? If one of the two probes speeds up or slows down, the radio signal timing will change, taking more or less time to get from one probe to the other. The amount of change is related to the force of gravity felt by the probe, and that in turn is related to the density of the material below. In practice, making a gravity map this way is extremely complex, but it’s been done before here at Earth using probes like GRACE and GOCE. It’s tried and true.

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The Moon and Venus make a pretty pair, don’t they?

I took this shot myself an hour ago as I write this, about 17:00 local time here in Boulder. I used my cell phone camera, then in Photoshop cropped it to 610 pixels wide (the biggest my blog width will allow) and blurred it a tiny bit to reduce the background noise. You can just barely see the "dark" part of the Moon, lit by reflected Earth light.

The pair were closer together last night, and the Moon’s motion around the Earth are separating them more as you read this. But they’ll be back together again on January 26th (they’ll get about 6° apart, 12 times the width of the Moon), and even closer on February 25th, when they’ll be about 3° apart! That’s a really nice photo op, so be prepared for it. If I can get such a nice shot with just my crappy phone, imagine what real photographers with nice equipment can get. I hope to see lots of gorgeous pictures of the pair then.

One of my favorite astrophotographers, Alan Friedman, spied something odd on the Moon.

Flying reindeer I’ll buy. But an inertialess propulsion system? C’mon.

Happy holidays everyone!

Credit: Alan Friedman

The pictures of Comet Lovejoy keep coming, each cooler than the one before. It’s hard to imagine topping the ones from the Space Station, but then you don’t have to imagine it when you can just look at this crazy amazing shot:

Holy Haleakala! [Click to stimulatedemissionate.]

Well, actually, "Holy Paranal!" This picture, by Gabriel Brammer, was taken at the Very Large Telescope observatory on Cerro Paranal in the Atacama desert in Chile, and it’s just stunning. The comet is obvious enough — you can still see the two tails — and the crescent Moon, somewhat overexposed, on the left. On the right is the VLT itself, firing a laser into the sky. The laser makes atoms high in the atmosphere glow, creating an artificial star that can be used to compensate for turbulence in the air, creating sharper images.

I love how the Milky Way is splitting the sky. You can see the dark hole of the Coal Sack, a thick dust cloud that absorbs the star light from behind it, and the Southern Cross in the middle of the frame. The two bright stars just below that are Alpha and Beta Centauri, the former being the closest star system to our own. The southern hemisphere gets a better view of the galaxy than we northerners do, since the geometry of the Earth’s tilt puts the center of the Milky Way higher up for them. I’m jealous enough just because of that, but to have this incredible comet visible too? Curse you antipodeans!

[UPDATE: The ESO has added a nice time lapse video to the mix, using Brammer's photos:

Sigh. So lovely.]

If you’re south of the Equator, the comet will be visible in the east before sunrise for a few more days at least. If you can, go take a look. Comets like this are extremely rare, and you may never get another chance like this again.

Image credit: Gabriel Brammer/European Southern Observatory