Starship Asterisk*

Comet NEOWISE Rising over the Adriatic Sea

Explanation: This sight was worth getting out of bed early. Two years ago this month, Comet C/2020 F3 (NEOWISE) rose before dawn to the delight of northern sky enthusiasts awake that early. Up before sunrise on July 8th, the featured photographer was able to capture in dramatic fashion one of the few comets visible to the unaided eye this century, an inner-Solar System intruder that has become known as the Great Comet of 2020. The resulting video detailed Comet NEOWISE from Italy rising over the Adriatic Sea. The time-lapse video combines over 240 images taken over 30 minutes. The comet was seen rising through a foreground of bright and undulating noctilucent clouds, and before a background of distant stars. Comet NEOWISE remained unexpectedly bright until 2020 August, with its ion and dust tails found to emanate from a nucleus spanning about five kilometers across.

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That's a lovely video! I love how some of the noctilucent clouds are surging like waves on the sea as they move across the sky.

The comet appears to move to the upper right in this video. I guess that is an effect caused by the Earth's own rotation. Obviously the comet has a motion of its own. Does anyone know how the comet is actually moving here (even if that movement isn't visible in the video)?

What are the stars visible to the upper right? The topmost pair of stars look just like Pollux and Castor, and the star to the lower right of them looks just like Alhena at the foot of Gemini.

But what is the bright star some distance below Pollux? There shouldn't be a bright star in that position, so could it possibly be Venus? But shouldn't Venus be even brighter than that? And it seems to me that Venus should be "above" Alhena, not "below" it.

Maybe those two topmost stars aren't Pollux and Castor after all?

Ann

Over 30 minutes of image the comet will not appear to move much at all, at least to an unaided eye. I found the Noctilucent clouds more fascinating!

I don't get it. So, the sun was rising up until about the 8 second mark, and then the sky becomes dark again?

johnnydeep wrote: ↑Tue Jul 26, 2022 2:43 pm I don't get it. So, the sun was rising up until about the 8 second mark, and then the sky becomes dark again?

The video repeats once. It's one 8-second video, played twice.

Chris Peterson wrote: ↑Tue Jul 26, 2022 3:05 pm

johnnydeep wrote: ↑Tue Jul 26, 2022 2:43 pm I don't get it. So, the sun was rising up until about the 8 second mark, and then the sky becomes dark again?

The video repeats once. It's one 8-second video, played twice.

Funny - I had thought that at first, but then was fooled into thinking that the second run-through began with a darker sky than the first and a different starting point for the comet. Probably because the start of the video is more easily overlooked than middle segments! ...Or maybe it's just me I think it would have been better to just slow the video down and not do the repeat.

johnnydeep wrote: ↑Tue Jul 26, 2022 3:22 pm

Chris Peterson wrote: ↑Tue Jul 26, 2022 3:05 pm

johnnydeep wrote: ↑Tue Jul 26, 2022 2:43 pm I don't get it. So, the sun was rising up until about the 8 second mark, and then the sky becomes dark again?

The video repeats once. It's one 8-second video, played twice.

Funny - I had thought that at first, but then was fooled into thinking that the second run-through began with a darker sky than the first and a different starting point for the comet. Probably because the start of the video is more easily overlooked than middle segments! ...Or maybe it's just me :-) I think it would have been better to just slow the video down and not do the repeat.

I don't think it needed to repeat. Of course, you can slow it down yourself from the YouTube settings icon at the bottom. I think it looks better at half speed.

Chris Peterson wrote: ↑Tue Jul 26, 2022 3:33 pm

johnnydeep wrote: ↑Tue Jul 26, 2022 3:22 pm

Chris Peterson wrote: ↑Tue Jul 26, 2022 3:05 pm

The video repeats once. It's one 8-second video, played twice.

Funny - I had thought that at first, but then was fooled into thinking that the second run-through began with a darker sky than the first and a different starting point for the comet. Probably because the start of the video is more easily overlooked than middle segments! ...Or maybe it's just me I think it would have been better to just slow the video down and not do the repeat.

I don't think it needed to repeat. Of course, you can slow it down yourself from the YouTube settings icon at the bottom. I think it looks better at half speed.

Yup. I often slow down YouTube videos to better notice details, but also speed up others to 1.5x or even 1.75x that have people talking so I can process them faster!

Comet NEOWISE over Lebanon; I couldn't get it over the
Adriatic Sea! Such a pretty Kitty!

Could the "wavy" part of the noctilucent clouds in today's APOD video be Kelvin-Helmholtz clouds?


Ann

Ann wrote: ↑Tue Jul 26, 2022 5:32 am The comet appears to move to the upper right in this video. I guess that is an effect caused by the Earth's own rotation. Obviously the comet has a motion of its own. Does anyone know how the comet is actually moving here (even if that movement isn't visible in the video)?

What are the stars visible to the upper right? The topmost pair of stars look just like Pollux and Castor, and the star to the lower right of them looks just like Alhena at the foot of Gemini.

But what is the bright star some distance below Pollux? There shouldn't be a bright star in that position, so could it possibly be Venus? But shouldn't Venus be even brighter than that? And it seems to me that Venus should be "above" Alhena, not "below" it.

Maybe those two topmost stars aren't Pollux and Castor after all?

Ann

All the stars visible in this image are in Auriga, the brightest being Theta Aur, just under 4° from the head of the comet. Near the top of the tail is 40 Aur, Above-right of Theta is Upsilon Aur then the brighter pair at the top are Nu Aur (lower) & Tau Aur (upper). The fainter pair just above them are HR 2025 and 28 Aur.

On that date, 08-July-2020, C/2020 F3 was moving more-or-less right to left vs. the background stars.

It's reminiscent of my first view and still picture of F3 on the morning of 07-July-2020, but I didn't have any noctilucent clouds here in New Jersey, USA.

Joe

Joe Stieber wrote: ↑Tue Jul 26, 2022 6:15 pm

Ann wrote: ↑Tue Jul 26, 2022 5:32 am The comet appears to move to the upper right in this video. I guess that is an effect caused by the Earth's own rotation. Obviously the comet has a motion of its own. Does anyone know how the comet is actually moving here (even if that movement isn't visible in the video)?

What are the stars visible to the upper right? The topmost pair of stars look just like Pollux and Castor, and the star to the lower right of them looks just like Alhena at the foot of Gemini.

But what is the bright star some distance below Pollux? There shouldn't be a bright star in that position, so could it possibly be Venus? But shouldn't Venus be even brighter than that? And it seems to me that Venus should be "above" Alhena, not "below" it.

Maybe those two topmost stars aren't Pollux and Castor after all?

Ann

All the stars visible in this image are in Auriga, the brightest being Theta Aur, just under 4° from the head of the comet. Near the top of the tail is 40 Aur, Above-right of Theta is Upsilon Aur then the brighter pair at the top are Nu Aur (lower) & Tau Aur (upper). The fainter pair just above them are HR 2025 and 28 Aur.

On that date, 08-July-2020, C/2020 F3 was moving more-or-less right to left vs. the background stars.

It's reminiscent of my first view and still picture of F3 on the morning of 07-July-2020, but I didn't have any noctilucent clouds here in New Jersey, USA.

Joe

Thanks, Joe, it makes sense. Every time I have seen noctilucent clouds, they have always been pretty much centered on Capella.

The pattern and brightness of the stars in the APOD just didn't look much like Auriga to me.

Ann

Thanks, Joe, it makes sense. Every time I have seen noctilucent clouds, they have always been pretty much centered on Capella.

The pattern and brightness of the stars in the APOD just didn't look much like Auriga to me.

Ann

Ann,

I think you hadn't realized it's a relatively small field-of-view in today's APOD. Here's a labeled wider-field image I took on the morning of 12-July-2020 with my iPhone 11 on a tripod. The comet moved to the left (away from Theta Aur) since 08-July. That's a friend of mine in the foreground doing some imaging.
Joe

Joe Stieber wrote: ↑Wed Jul 27, 2022 2:59 am

Thanks, Joe, it makes sense. Every time I have seen noctilucent clouds, they have always been pretty much centered on Capella.

The pattern and brightness of the stars in the APOD just didn't look much like Auriga to me.

Ann

Ann,

I think you hadn't realized it's a relatively small field-of-view in today's APOD. Here's a labeled wider-field image I took on the morning of 12-July-2020 with my iPhone 11 on a tripod. The comet moved to the left (away from Theta Aur) since 08-July. That's a friend of mine in the foreground doing some imaging.

IMG_0017-labels.jpg

Joe

Your phone took that? Did you use any special settings or did you just let the phone do whatever automatic adjusting it does?

Joe Stieber wrote: ↑Wed Jul 27, 2022 2:59 am

Thanks, Joe, it makes sense. Every time I have seen noctilucent clouds, they have always been pretty much centered on Capella.

The pattern and brightness of the stars in the APOD just didn't look much like Auriga to me.

Ann

Ann,

I think you hadn't realized it's a relatively small field-of-view in today's APOD. Here's a labeled wider-field image I took on the morning of 12-July-2020 with my iPhone 11 on a tripod. The comet moved to the left (away from Theta Aur) since 08-July. That's a friend of mine in the foreground doing some imaging.

Click to view full size image

Joe

Wow, thanks a million, Joe!

So it wasn't the Twins that I saw, but the Kids!

johnnydeep,

The picture was a simple snapshot taken with automatic settings and no post-processing (besides size reduction and then a labeled mouseover copy for my web page). The iPhone 11 was mounted on a tripod, and even though the EXIF data said it was a one-second exposure, I thought it said 30 seconds prior to pressing the shutter release, which would correspond with the aircraft track in the upper-right corner. Keep in mind that I only activated this smartphone two days earlier, so I was hardly an expert yet. It was taken at 4:03 am EDT, 19 minutes after the start of astronomical twilight and there was a 91% illuminated moon to the south (outside the frame to the right).

----

Ann,

The Kids (near Capella) aren't in the APOD, they are outside the top of the frame. What looks sort of like Castor and Pollux are likely Nu & Tau Aur as shown in this labeled screen clip...


Remember that the head of C/2020 F3 and Theta Aur are less than 4 deg apart at the time. The Kids were 14+ deg away from the comet's head.

Joe