Archive
01/26/2018 – Ephemeris – The Moon tonight: The Bay of Rainbows
Ephemeris for Friday, January 26th. The Sun will rise at 8:08. It’ll be up for 9 hours and 34 minutes, setting at 5:43. The Moon, 2 days past first quarter, will set at 3:59 tomorrow morning.
A look at the Moon tonight will reveal that the sunrise line, or terminator has almost completely revealed the large sea of Showers or Mare Imbrium to the upper left of center of the gibbous disk. At the extreme upper left straddling the terminator is one of my favorite features, the Bay of Rainbows or Sinus Iridium. It’s a colorful name for something that’s as gray as the rest of the Moon. It looks like a bay off of Imbrium, and has an arch like a rainbow. It’s arch is the Jura Mountains, which jut into Mare Imbrium at Cape Heraclide, just catching sunlight, and Cape Laplace farther into morning. What’s cool is catching it as the sunlight is hitting the mountains while the convex floor, following the Moon’s curvature is only partially illuminated.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Moon at 8 p.m. January 26, 2018 highlighting Sinus Iridium. Created using Virtual Moon Atlas.
Sinus Iridium photographed by the Lunar Reconnaissance Orbiter as texture mapped on the globe of the Virtual Moon Atlas.
Sinus Iridium at sunrise. Photo by “Seb2003” on http://forums.futura-sciences.com/materiel-astronomique-photos-damateurs/5809-images-de-lune.html.
06/18/2013 – Ephemeris – The moon’s most striking feature, the Jura Mountains and the Bay of Rainbows
Ephemeris for Tuesday, June 18th. Today the sun will be up for 15 hours and 33 minutes, setting at 9:30. The moon, 2 days past first quarter, will set at 2:48 tomorrow morning. Tomorrow the sun will rise at 5:56.
On the moon tonight the gibbous phase and the terminator on the left side of the moon is revealing a large semi circular mountain range called the Jura Mountains that encloses a flat lava plain that looks like a bay in the margin of the Sea of Showers or Mare Imbrium. The bay is Sinus Iridium, or Bay of Rainbows. It is easily visible in binoculars this evening when the sunrise line is crossing the bay. The Jura Mountains will appear as a hook at the upper left edge of the moon. That’s about the coolest sight that’s visible on the moon that can be seen with binoculars. It’s especially striking if seen in a small telescope. Though the bay is the same gray as the rest of the moon, at least its name is colorful.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Bay of Rainbows (Sinus Iridium) within the Jura Mountains on the moon. Created using Virtual Moon Atlas.
Bob Moler's Ephemeris Blog 