APOD: Quarter Moon and Sister Stars (2024 Sep 03)

[APOD Robot]

Quarter Moon and Sister Stars

Explanation: Nine days ago, two quite different sky icons were imaged rising together. Specifically, Earth's Moon shared the eastern sky with the sister stars of the Pleiades cluster, as viewed from Alberta, Canada. Astronomical images of the well-known Pleiades often show the star cluster's alluring blue reflection nebulas, but here they are washed-out by the orange moonrise sky. The half-lit Moon, known as a quarter moon, is overexposed, although the outline of the dim lunar night side can be seen by illuminating earthshine, light first reflected from the Earth. The featured image is a composite of eight successive exposures with brightnesses adjusted to match what the human eye would see. The Moon passes nearly -- or directly -- in front of the Pleaides once a month.

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[SeedsofEarfth]

Isn't that a half moon?

[gmPhil]

Isn't that a half moon?

Came to ask the same thing. It is half of a "full moon", so surely...

[Chris Peterson]

Isn't that a half moon?

It was a "third quarter moon". Not "quarter" by itself, and certainly commonly called "half".

[johnnydeep]

Isn't that a half moon?

It was a "third quarter moon". Not "quarter" by itself, and certainly commonly called "half".

I think of it as although it's face is half lit from our perspective, it's deemed a quarter moon since it's a quarter of the way through a full cycle of phases:

Click to view full size image

[Chris Peterson]

Isn't that a half moon?

It was a "third quarter moon". Not "quarter" by itself, and certainly commonly called "half".

I think of it as although it's face is half lit from our perspective, it's deemed a quarter moon since it's a quarter of the way through a full cycle of phases:

Click to view full size image

Except in this case it's three quarters of the way through a full cycle. It's a waning moon.

[Why cats?]

I expected the link in the text to “eight successive” exposures to show those eight individual images instead of a picture of eight cats. Any explanation?

[johnnydeep]

I expected the link in the text to “eight successive” exposures to show those eight individual images instead of a picture of eight cats. Any explanation?

It meant to be humorous. Yes, it's true, even astrophotographers and astronomers have a sense of humor. There are often such links to "cute" cat or dog images left as happy surprises for the serious minded.

[johnnydeep]

It was a "third quarter moon". Not "quarter" by itself, and certainly commonly called "half".

I think of it as although it's face is half lit from our perspective, it's deemed a quarter moon since it's a quarter of the way through a full cycle of phases:

Click to view full size image

Except in this case it's three quarters of the way through a full cycle. It's a waning moon.

Well, it marks one of the four natural quarter positions around the circle of moon phases. But I phrased it badly in my first post.

[Chris Peterson]

I think of it as although it's face is half lit from our perspective, it's deemed a quarter moon since it's a quarter of the way through a full cycle of phases:

Click to view full size image

Except in this case it's three quarters of the way through a full cycle. It's a waning moon.

Well, it marks one of the four natural quarter positions around the circle of moon phases. But I phrased it badly in my first post.

I think that calling this a "quarter moon", as phrased in the caption, is poor wording and likely to confuse. I don't think anybody would go outside and see this moon and call it a quarter moon. Most people would say it's a half moon, and people who are more technical would say it's a third-quarter moon.

[johnnydeep]

Except in this case it's three quarters of the way through a full cycle. It's a waning moon.

Well, it marks one of the four natural quarter positions around the circle of moon phases. But I phrased it badly in my first post.

I think that calling this a "quarter moon", as phrased in the caption, is poor wording and likely to confuse. I don't think anybody would go outside and see this moon and call it a quarter moon. Most people would say it's a half moon, and people who are more technical would say it's a third-quarter moon.

Yeah. And I guess calling the full moon a second quarter moon, and the new moon a fourth quarter moon doesn't help clarify things much.

[Ann]

I expected the link in the text to “eight successive” exposures to show those eight individual images instead of a picture of eight cats. Any explanation?

One cat. Two cats. Three cats. Two more cats, and maybe four.

And Bastet, the cat goddess of Egypt, with the Sun and the Moon.

Bastet, the cat goddess of Egypt, with the Sun and the Moon. Credit: Etsy.com

---

And of course, then there is the Moon and the Pleiades, minus any cats.

The Nebra sky disc, c. 1800–1600 BC. The group of seven stars at upper right is interpreted as the Pleiades. Credit: Frank Vincentz

---

Frank Vincentz' photo is an edited version of this photo, https://commons.wikimedia.org/wiki/File ... y_disk.jpg.

Ann

[johnnydeep]

As for the Nebra Sky Disk, sadly, the ridged circular arc at the bottom is apparently not the mirror from a long lost reflecting telescope, but the "solar boat" of the Sun deity!

The Sun was sometimes envisioned as traveling through the sky in a boat. A prominent example is the solar barque used by Ra in ancient Egyptian mythology.[8] The Neolithic concept of a "solar barge" (also "solar bark", "solar barque", "solar boat" and "sun boat", a mythological representation of the Sun riding in a boat) is found in the later myths of ancient Egypt, with Ra and Horus. Several Egyptian kings were buried with ships that may have been intended to symbolize the solar barque,[9] including the Khufu ship that was buried at the foot of the Great Pyramid of Giza.[10]

And:

[Chris Peterson]

I expected the link in the text to “eight successive” exposures to show those eight individual images instead of a picture of eight cats. Any explanation?

And of course, then there is the Moon and the Pleiades, minus any cats.

The Nebra sky disc, c. 1800–1600 BC. The group of seven stars at upper right is interpreted as the Pleiades. Credit: Frank Vincentz

---

Surely I see the Cheshire Cat in there.

Cats are very in now. Apparently America is just swarming with childless cat ladies!

[Ann]

I expected the link in the text to “eight successive” exposures to show those eight individual images instead of a picture of eight cats. Any explanation?

And of course, then there is the Moon and the Pleiades, minus any cats.

The Nebra sky disc, c. 1800–1600 BC. The group of seven stars at upper right is interpreted as the Pleiades. Credit: Frank Vincentz

---

Surely I see the Cheshire Cat in there.

Well, there are some similarities...

The Cheshire Cat with stars. Credit: Cheshire Cat AI?

---

Cats are very in now. Apparently America is just swarming with childless cat ladies!

Indeed, there are many cat ladies, and apparently even more cat ladies' cats...

Happy cat lady with cats. Credit: Deep Dream Generator, or, Hi there, AI!

---

Ann

[Guest]

The arc on the Nebra disk is not a boat, it is the path of the star Vega near the winter solstice.

[Chris Peterson]

The arc on the Nebra disk is not a boat, it is the path of the star Vega near the winter solstice.

Nobody knows exactly what all the elements on the disk are.

[Guest]

All elements are explained at dcwalley.com/sky-disc. Seems convincing.

[Chris Peterson]

All elements are explained at dcwalley.com/sky-disc. Seems convincing.

Not at all. It seems like one plausible hypothesis, of several.