Happy Friday!
It’s been cloudy on and off, so when the skies cleared Wednesday evening, I was out in the yard with the new scope. Time to snag an observation for Alt-Text Friday.
If you’re just tuning in, Friday posts are descriptions of skygazing, suitable for my blind and low-vision buddies. I sure have fun writing these. Hopefully everyone gets something out of it, no matter how you interact with the universe.
The Crescent Moon
The clouds of the day had mostly cleared. The sun had just gone down, leaving a tangerine glow in the west. The black silhouette of the pine grove jutted against the sky, pointing to Venus and Saturn. The planets sparkled in the sunset.
They appeared nearby in the sky, but, according to my calculations, Venus, a clear white light, was 142 million miles away. Yellow-tinged Saturn was nearly a billion miles distant. No wonder it looked much dimmer than Venus.
Above this cosmic greeting, higher up in the deeper blue part of the sky, roughly 30 degrees above the horizon, hung a crescent moon.
It was thin, like a fingernail clipping, or the edge of a wine glass. The sky was still light, so it shone with a warm silver through the dark blue.
In the distance, a dog barked, and a truck rumbled home to dinner along Campbell highway.
I swung the telescope towards the moon.
General Telescope Views
People have been observing the moon through a telescope since 1609 - and it never gets old.
(Fun Friday Fact guaranteed to lose you your lunch money: English astronomer Thomas Harriot drew a lunar map on August 5th, 1609, beating Galileo by four months.)
A jumble of craters - looking like dents or pocks - flat plains of cooled lava first thought to be seas - and an endless nuance of grays. There’s bright, nearly white of the rocks tossed aside by lunar impact, all the way to the dark basalt of the ancient lava flows. As the moon orbits the earth, going through her phases, the shadow line, or terminator, sweeps across the surface, casting new features into sharp relief night by night, and, if one pays close attention, hour by hour.
Mare Crisium
Even without a telescope, the moon has noticeable dark splotches on the surface.
Wednesday’s crescent provided a stunning look at Mare Crisium - the Sea of Crises.
Italian astronomer and Jesuit priest Giovanni Battista Riccioli (please, say that out loud - what a NAME) mapped many of the lunar features, and named craters.
He called these dark areas “Mare” (pronounced “mar a”) or “seas”, thinking they might be. Instead of water, they’re vast plains of cooled lava - enough to make any astronaut thirsty. Estimates put Mare Crisium between 3.8 and 4.6 billion years old.
Hey buddy, and you think your problems are new.
What It Looked Like
At low power, the view reminded me of the Death Star, with Mare Crisium about the same size in proportion to that big dent thing in the front of the Death Star. (Obviously, my Star Wars knowledge is lacking.) Although - the feature is near the edge of the moon, not the middle.
A quick edit: I just heard back from a colleague mentioning this isn’t a particularly useful parallel. She brings up an interesting point: we need to get more 3D printed models of space lore out there. If you haven’t felt a model or toy of the Death Star, picture a ping pong ball with a small dent.
Fairly round, the lava plain sat lower than the surrounding terrain. The floor of the mare was incredibly smooth, with only a hint of a wrinkle in the frozen rock. It looked small through the telescope, but is roughly the area of Great Britain.
Craters Picard, Pierce, and Swift dotted the edge right where the terminator (shadow line) crossed. Swift, the smallest, about six miles across, and was seen easily. Not too shabby for an observer standing over two hundred thousand miles away, eh?
A faint rim of a “ghost crater” poked up across the way. The crater had formed, then the lava flowed, flooding the crater till only the uppermost lip of it could be detected.
Most of Mare Crisium is ringed by rugged terrain that reminded me of coral. (Really really BIG coral.)
As the night sky on earth continued to darken, the evening shadows on the moon appeared to turn from blue to black.
Off the edge (or limb) of the moon, a distant star glittered from deep space, trillions of miles away.
Stepping away from the telescope, I looked up at the moon. The sky had turned a deep blue fading to dark gray black. The crescent remained a beautiful warm silver, and the unlit side of the moon glowed a pale ashen gray. Earthshine. If we were on the moon, we’d see a nearly full Earth, and revel in Earthlight, much as poets of this world write about moonlight.
It sure is a beautiful, fascinating universe!
Speaking of Earth….
Treasures from Earth
Obviously we need to listen to Beethoven’s Sonata #14 Op. 27 No.2….
The Moonlight.
Clear skies,
Josh
Luv this. Moon needs people to care about it too. Thanks for doing it :)