I’m a happy cheerleader for the moon. I think it’s because I’ve stared at countless faint galaxies and spent hours eking out planetary details through choppy air. So last night, when I turned the telescope at the first quarter moon, it felt as though I’d arrived in the garden of plenty.
Craters everywhere, rugged mountains poking from the beige cream of the lunar seas and beautiful shadows stretching like figures in a Dali painting across a landscape at once familiar and yet totally alien.
There’s so much to enjoy even in small scopes at low power. A magnification of 50-75x is sufficient to see most of the features in the photo at right.
I’d love to feast my eyes on the two freshly-minted, man-made craters punched into a mountainside near the moon’s north pole. On Dec. 17, 2012, the twin GRAIL probes, nicknamed Flow and Ebb, were intentionally crashed there after wrapping up a successful mission mapping the moon’s gravity field and interior.
Animation showing the final flight path for NASA’s twin Gravity Recovery and Interior Laboratory (GRAIL) mission spacecraft as they headed for crash landings
Why smack the moon? It was NASA’s plan to squeeze one last bit of science out of the mission. The Lunar Reconnaissance Orbiter (LRO), which orbits the moon and takes closeup photos of it surface, was placed into position to study the last whiffs of the dust plumes kicked up by the two washing-machine-sized probes. Each weighed 440 lbs. (200 kg) and were traveling at 3,800 mph (6,100 km/h) when they struck the mountain.
Later, the LRO’s camera zoomed in for a look at the two craters resulting from the crashes and pinpointed them both despite their tiny size – only 13-20 feet (4-6 meters) in diameter. Named Ebb and Flow (of course!), they’re surrounded by faint, dark ejecta or rock sprays gouged from the crust during impact.
Radiation in sunlight darkens lunar dust. Fresh lunar craters are typically surrounded by bright ejecta rays created since the impact exposes dust and rock beneath the surface that’s been shielded from sunlight. Ebb and Flow are ringed in darker material; scientists suspect spacecraft material has mixed with the ejecta adding yet another “we were here” signpost to the scene.
I’ll return to observing the moon the next clear night. Maybe I’ll get even luckier than I did on Tuesday. Along the edge of its unlit half, a bright star in Gemini hovered briefly before suddenly disappearing behind the moon. These little “coverups” occur regularly as the moon rolls along its orbit, hiding and then “releasing” this star and that. On good nights, lunar observers are like that star, completely absorbed by our nearest cosmic neighbor.