Astronomy Picture of the Day - Western Moon, Eastern Sea

APOD.NASA.gov ^ | 28 Jan, 2022 | Image Credit & Copyright: Tom Glenn

[MtnClimber]

Explanation: The Mare Orientale, Latin for Eastern Sea, is one of the most striking large scale lunar features. The youngest of the large lunar impact basins it's very difficult to see from an earthbound perspective. Still, taken during a period of favorable tilt, or libration of the lunar nearside, the Eastern Sea can be found near top center in this sharp telescopic view, extremely foreshortened along the Moon's western edge. Formed by the impact of an asteroid over 3 billion years ago and nearly 1000 kilometers across, the impact basin's concentric circular features are ripples in the lunar crust. But they are a little easier to spot in more direct images of the region taken from lunar orbit. So why is the Eastern Sea at the Moon's western edge? The Mare Orientale lunar feature was named before 1961. That's when the convention labeling east and west on lunar maps was reversed.

[MtnClimber]

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For more detail go to the link and click on the image for a high definition image. You can then move the magnifying glass cursor then click to zoom in and click again to zoom out. When zoomed in you can scan by moving the side bars on the bottom and right side of the image.

[MtnClimber]

[MtnClimber]

Pinging the APOD list.

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[ProtectOurFreedom]

The moon is 3,474 km in diameter. Getting hit by an asteroid 1,000 km in diameter would do a lot of damage, far more than leaving a crater. You’d think it would have blown the moon to bits. Of course, if they have the same density, then the object that hit the moon would have a mass (1,000/3,474)^3 or 2.4% of the moon’s mass.

[MtnClimber]

That made me scratch my head too. I would guess 1000m, not 1000km!

[Telepathic Intruder]

"That's when the convention labeling east and west on lunar maps was reversed."

Never the twain shall meet, but they can change places. East identified as a transwest, and vice versa. All it takes is some corrective cosmetics and attire.

[MtnClimber]

Trans? Not the Moon. No way. Maybe Uranus, but not the MOON!

[EvilCapitalist]

Are you making Uranus jokes on a Moon thread?

[Telepathic Intruder]

The 1,000 km size is in reference to the impact basin’s size, not the asteroid, which was about 40 miles across according to Wiki.

[MtnClimber]

OK, thanks! The text is confusing even after reading it about four times!

[Telepathic Intruder]

Well I have seen some actual NASA mistakes, one on this very site, but they are about as rare as comet sightings. You never can tell.

[ProtectOurFreedom]

Yes, 1,000 m would make more sense, but what’s a few orders of magnitude among friends? The number 3 isn’t very large, is it

[ProtectOurFreedom]

Thanks. I reread it and you are right. The sentence is clear on that.

[jonrick46]

I would love to know what size telescope was used to photograph that image of the moon.

[gloryblaze]

The “earthbound perspective” link is colorful and clear - in miles. But no kitty or pup.