Happy Day of the Moon

Mondays, am I right? Turns out, not only is the start of the conventional work week*, but it’s also the day of the Moon. Literally. Monday is derived from the Old English Mōnandæg. Mōna means Moon in that language. Wikipedia states that it was a translation of the Latin “dies lunae,” day of Luna, the Latin name for Earth’s constant companion in the celestial dance.

This Monday I was up early, as is my elderly cat Mittens’s wont, since he loves his “pill treats,” and wants them as soon as the sky begins to lighten. After taking care of him, I took my telescope outside for some morning Moon viewing. I actually started by viewing Jupiter. It may surprise you to learn that Jupiter can be seen in daylight, in a telescope. I was helped by starting just before actual dawn, and the brightening sky was still deep blue enough that Jupiter stood out. I was able to view the King of Planets and three of its four Galilean moons.

I then turned my telescope to Luna, which was “waning gibbous,” the evocative name its third quarter is given as it does its monthly dance with the Earth. The air can be seen bubbling around the edges of the image, but the view is still sharp along the terminator, where the sunset is setting.

Getting in a little Moon viewing on this day of the Moon is a fun way to begin the week and honor the origin of this day’s name.

A Moon shot

I’m working on a longer post about my love for stargazing, but after being up to late stargazing lately, coupled with Mittens waking me up too early for his pill “treats”, today ended up being more of a slog than I’d imagined, so I thought I’d share an image from last night’s twilight viewing of Luna, taken through a refractor telescope. The purple border on the right edge of the Moon is caused by something called “chromatic aberration,” which is an artifact of the two lenses of this particular scope and its short focal length.

Still the terminator, on the lefthand edge of the lunar image here, is sharp. The terminator is the boundary between day and night on the Moon, which changes hour by hour as it moves around the Earth.

In the lower left part of the terminator is a line of craters, the largest an oval. That’s Schickard, an impact crater which looks oblong because of foreshortening.