APOD: North Celestial Tree (2022 Jul 28)

Comments and questions about the APOD on the main view screen.
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APOD: North Celestial Tree (2022 Jul 28)

Post by APOD Robot » Thu Jul 28, 2022 4:05 am

Image North Celestial Tree

Explanation: An ancient tree seems to reach out and touch Earth's North Celestial Pole in this well-planned night skyscape. Consecutive exposures for the timelapse composition were recorded with a camera fixed to a tripod in the Yiwu Desert Poplar Forests in northwest Xinjiang, China. The graceful star trail arcs reflect Earth's daily rotation around its axis. By extension, the axis of rotation leads to the center of the concentric arcs in the night sky. Known as the North Star, bright star Polaris is a friend to northern hemisphere night sky photographers and celestial navigators alike. That's because Polaris lies very close to the North Celestial Pole on the sky. Of course it can be found at the tip of an outstretched barren branch in a postcard from a rotating planet.

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Ann
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Re: APOD: North Celestial Tree (2022 Jul 28)

Post by Ann » Thu Jul 28, 2022 4:32 am

AncientTreeNCP_Dai1024[1].jpg
North Celestial Tree
Image Credit & Copyright: Jeff Dai (TWAN)
Bullseye! :D 🎯

It's a very striking APOD. Nevertheless, star trail images always drive me slightly crazy, because I want to identify individual star trails, and I can never do it.

Below the central tree in the APOD there appears to be two star clusters. Does anyone have an inkling as to what clusters they might be?

There aren't that many great clusters of reasonably bright stars not too far from Polaris. Forget the great globular of the north, M13, because it wouldn't show up as anything but an individual line in an image like this. I was thinking of Alpha Persei moving cluster, but I doubt it. How about Cassiopeia? Cassiopeia is a northern constellation, there are five bright stars there, and there are several clusters scattered among them adding more starshine to the scene.

Ann
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Chris Peterson
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Re: APOD: North Celestial Tree (2022 Jul 28)

Post by Chris Peterson » Thu Jul 28, 2022 4:47 am

Ann wrote: Thu Jul 28, 2022 4:32 am
AncientTreeNCP_Dai1024[1].jpg
North Celestial Tree
Image Credit & Copyright: Jeff Dai (TWAN)
Bullseye! :D 🎯

It's a very striking APOD. Nevertheless, star trail images always drive me slightly crazy, because I want to identify individual star trails, and I can never do it.

Below the central tree in the APOD there appears to be two star clusters. Does anyone have an inkling as to what clusters they might be?

There aren't that many great clusters of reasonably bright stars not too far from Polaris. Forget the great globular of the north, M13, because it wouldn't show up as anything but an individual line in an image like this. I was thinking of Alpha Persei moving cluster, but I doubt it. How about Cassiopeia? Cassiopeia is a northern constellation, there are five bright stars there, and there are several clusters scattered among them adding more starshine to the scene.

Ann
FWIW, the latitude here is about 43°, meaning the declination of the stars at the horizon are going to be 47°. We don't know exactly where the true horizon is in this image, but it's probably not too far below the apparent horizon. Maybe assume that we're seeing about a 45° circle around Polaris here.
Chris

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Re: APOD: North Celestial Tree (2022 Jul 28)

Post by BoJ » Thu Jul 28, 2022 8:18 am

I always ask people about the direction of the rotation of the stars (and the Sun), so to the readers: Clockwise or counterclockwise in the northern hemisphere? :D

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Re: APOD: North Celestial Tree (2022 Jul 28)

Post by De58te » Thu Jul 28, 2022 8:27 am

BoJ wrote: Thu Jul 28, 2022 8:18 am I always ask people about the direction of the rotation of the stars (and the Sun), so to the readers: Clockwise or counterclockwise in the northern hemisphere? :D
Every time lapse video of the star motion I've seen rotate counterclockwise around Polaris.

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Re: APOD: North Celestial Tree (2022 Jul 28)

Post by orin stepanek » Thu Jul 28, 2022 11:13 am

AncientTreeNCP_Dai1024.jpg
Tree is pretty much dead; but makes a nice pointer!
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