Starship Asterisk*

A Meteor Wind over Tunisia

Explanation: Does the Earth ever pass through a wind of meteors? Yes, and they are frequently visible as meteor showers. Almost all meteors are sand-sized debris that escaped from a Sun-orbiting comet or asteroid, debris that continues in an elongated orbit around the Sun. Circling the same Sun, our Earth can move through an orbiting debris stream, where it can appear, over time, as a meteor wind. The meteors that light up in Earth's atmosphere, however, are usually destroyed. Their streaks, though, can all be traced back to a single point on the sky called the radiant. The featured image composite was taken over two days in late July near the ancient Berber village Zriba El Alia in Tunisia, during the peak of the Southern Delta Aquariids meteor shower. The radiant is to the right of the image. A few days ago our Earth experienced the peak of a more famous meteor wind -- the Perseids.

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Is this supposed to be an accurate composite?
I don't like to suggest this, but it looks somewhat faked... Look at how the meteors are in-line with each other. That's not how a random distribution would look.

I believe the random motion between the meteors is minor compared to the collision speed between the Earth and the meteor/comet trail. Thats why they seem to travel across the sky like that. Lens distortion like fisheye also affect the image.

Does anyone have a suggestion on software for producing a composite meteor image? Stacking seems to wash them out.

daddyo wrote: ↑Tue Aug 16, 2022 5:40 am I believe the random motion between the meteors is minor compared to the collision speed between the Earth and the meteor/comet trail. Thats why they seem to travel across the sky like that. Lens distortion like fisheye also affect the image.

Does anyone have a suggestion on software for producing a composite meteor image? Stacking seems to wash them out.

Most of the meteors are in-line with other meteors. There are four lines of meteors, three in a row, basically nose-to-tail. And there are other meteors basically nose-to-tail. That has no relation to collision speed or lens distortion.

(I'm not a photograph, so I ask)

Since catching many meteors requires time (at least a couple of minutes), why the sky didn't turn, making arc out of stars?
(not clear ? I'm french )

I vote FAKE NEWS

My opinion they picked and chose the exposures to get the meteors to look parallel. Here is their explanation from the Facebook link which I used a translator to translate into English;

1h30 ago for the sky with the canon 6d in exposures of 180s
there are also 50 hours to capture the maximum number of shooting stars: 16 hours with the D850 in 45s exposures, 16 hours with the D5500 in 30s exposures, 10 hours with the Sony A7s with 15s exposures and 8 hours with the Canon 6d in 180s exposures with different focal lengths (14mm, 24mm, 35mm, 50mm, 105mm, 135mm)

The meteor wind blowing over Berber, Tunisia!
Wonder why the village was abandoned; noticed some modern
looking domes in the video! Pretty Kitty!

"Meteor Shower Radiation" ????

heehaw wrote: ↑Tue Aug 16, 2022 1:26 pm "Meteor Shower Radiation" ????

If you go to the imager's site, it's clear that English isn't his first language. But the meaning is clear enough, even if some of the word choices are a bit off.

FLPhotoCatcher wrote: ↑Tue Aug 16, 2022 4:42 am Is this supposed to be an accurate composite?
I don't like to suggest this, but it looks somewhat faked... Look at how the meteors are in-line with each other. That's not how a random distribution would look.

FLPhotoCatcher wrote: ↑Tue Aug 16, 2022 6:49 am

daddyo wrote: ↑Tue Aug 16, 2022 5:40 am I believe the random motion between the meteors is minor compared to the collision speed between the Earth and the meteor/comet trail. Thats why they seem to travel across the sky like that. Lens distortion like fisheye also affect the image.

Does anyone have a suggestion on software for producing a composite meteor image? Stacking seems to wash them out.

Most of the meteors are in-line with other meteors. There are four lines of meteors, three in a row, basically nose-to-tail. And there are other meteors basically nose-to-tail. That has no relation to collision speed or lens distortion.

Tobias wrote: ↑Tue Aug 16, 2022 8:56 am (I'm not a photograph, so I ask)

Since catching many meteors requires time (at least a couple of minutes), why the sky didn't turn, making arc out of stars?
(not clear ? I'm french )

I vote FAKE NEWS

Yes, to some extent, it is fake. And we should understand that some of this is accepted, even necessary practice.

Any such image, to attempt to represent what our eyes and brains would have seen, had we been sitting there for 2 full nights in a row, will have to be put together from a set of very different photographs. I think the astrophotographer who composed this did the following. First, as he describes in detail on his facebook at the "featured image" caption link, he collected 50 hours of work with 4 cameras to capture the meteor trails. Next, he must have obtained one or more foreground landscape images and one or more sky images. At very different exposures. Finally, he would have put it all together.

FLPhotocatcher has an interesting point. I would think, for faithfulness of the experience, the meteor trails should have been placed "where they were on the sky", when stitching together, but perhaps this was not totally accurately done. Of course, we could ask Makrem Larnaout at:
https://www.facebook.com/TheRoyalAstronomicalSociety
if one has a question about this. Having used 4 cameras to capture the meteors, some manual placement of the trails may have been necessary. I certainly do understand that APOD viewers, at least, would want this to be done with as little artistic license as possible. And I think it was astute of FLPhotoCatcher to have noticed the alignments.

What are the red/orange clusters on the left?

heehaw wrote: ↑Tue Aug 16, 2022 1:26 pm "Meteor Shower Radiation" ????

Oops. This was my mistake. Fixed it on the main NASA APOD. Apologies. Thanks for pointing that out.
- RJN

hypatia wrote: ↑Tue Aug 16, 2022 7:37 pm What are the red/orange clusters on the left?

There are some striking red nebulas in the image. At lower left, there is the Heart and Soul nebulas:


At upper left in the APOD, there is the NGC 7822 nebula. I'm showing you a narrowband image where the nebula does not look red, as it does in the APOD.


At upper right, at least to the right of the bright band of the Milky Way, is a small red comma-shaped nebula, the Pacman Nebula:


Ann

Thanks Ann.