Comments and questions about the
APOD on the main view screen.
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APOD Robot
- Otto Posterman
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Post
by APOD Robot » Tue Jun 13, 2023 4:05 am
Moons Across Jupiter
Explanation: Jupiter's moons
circle Jupiter. The
featured video depicts Europa and Io, two of
Jupiter's largest moons, crossing in front of the grand planet's
Great Red Spot, the largest known storm system in our
Solar System. The video was composed from images taken by the
robotic Cassini spacecraft as it passed Jupiter in 2000, on its way to Saturn. The two moons visible are
volcanic Io, in the distance, and
icy Europa. In the time-lapse video, Europa appears to overtake Io, which is
odd because Io is closer to
Jupiter and moves faster. The explanation is that the motion of the fast
Cassini spacecraft changes the camera location significantly during imaging. Jupiter is currently being visited by
NASA's robotic
Juno spacecraft, while
ESA's
Jupiter Icy Moons Explorer (JUICE),
launched in April, is enroute.
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javachip3
Post
by javachip3 » Tue Jun 13, 2023 5:23 am
This appears to be a "simulated" time-lapse video, with artist's interpretation. Jupiter's clouds do not move at all during the video. Neither do Io's or Europa's terminators, while Jupiter's terminator approaches at the right.
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RDaneelOlivaw
Post
by RDaneelOlivaw » Tue Jun 13, 2023 7:01 am
I'm wondering what kind of gravitational interplay there is between Europa and Io when they pass as close to each other as they appear to in this video? -- Ron
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alex555
Post
by alex555 » Tue Jun 13, 2023 7:52 am
javachip3 wrote: ↑Tue Jun 13, 2023 5:23 am
This appears to be a "simulated" time-lapse video, with artist's interpretation. Jupiter's clouds do not move at all during the video. Neither do Io's or Europa's terminators, while Jupiter's terminator approaches at the right.
No. The clouds of the Great Red Spot are clearly seen rotating clockwise, as well as the parallel movements of the white clouds further below
Alex
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Chris Peterson
- Abominable Snowman
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by Chris Peterson » Tue Jun 13, 2023 12:35 pm
RDaneelOlivaw wrote: ↑Tue Jun 13, 2023 7:01 am
I'm wondering what kind of gravitational interplay there is between Europa and Io when they pass as close to each other as they appear to in this video? -- Ron
Ganymede, Europa, and Io are in a 4:2:1 orbital resonance... created and maintained by their mutual gravitational influence.
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johnnydeep
- Commodore
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Post
by johnnydeep » Tue Jun 13, 2023 1:30 pm
alex555 wrote: ↑Tue Jun 13, 2023 7:52 am
javachip3 wrote: ↑Tue Jun 13, 2023 5:23 am
This appears to be a "simulated" time-lapse video, with artist's interpretation. Jupiter's clouds do not move at all during the video. Neither do Io's or Europa's terminators, while Jupiter's terminator approaches at the right.
No. The clouds of the Great Red Spot are clearly seen rotating clockwise, as well as the parallel movements of the white clouds further below
Alex
Correction: the Red Spot clouds are rotating
counter clockwise.
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}
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orin stepanek
- Plutopian
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Post
by orin stepanek » Tue Jun 13, 2023 9:09 pm
Nice set of moons!
![Very Happy :D](./images/smilies/icon_biggrin.gif)
Orin
Smile today; tomorrow's another day!
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pclark@bigpond.net.au
Post
by pclark@bigpond.net.au » Wed Jun 14, 2023 4:20 am
alex555 wrote: ↑Tue Jun 13, 2023 7:52 am
javachip3 wrote: ↑Tue Jun 13, 2023 5:23 am
This appears to be a "simulated" time-lapse video, with artist's interpretation. Jupiter's clouds do not move at all during the video. Neither do Io's or Europa's terminators, while Jupiter's terminator approaches at the right.
No. The clouds of the Great Red Spot are clearly seen rotating clockwise, as well as the parallel movements of the white clouds further below
Alex
Erm, no, the Red Spot clouds don't clearly rotate at all. The caption uses the term "depicts" for good reason, Cover the moons with your hand and watch the background image very closely, marking point features. If you see movement you may need to see your optometrist.
![Wink ;)](./images/smilies/icon_wink.gif)
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Chris Peterson
- Abominable Snowman
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by Chris Peterson » Wed Jun 14, 2023 4:31 am
pclark@bigpond.net.au wrote: ↑Wed Jun 14, 2023 4:20 am
alex555 wrote: ↑Tue Jun 13, 2023 7:52 am
javachip3 wrote: ↑Tue Jun 13, 2023 5:23 am
This appears to be a "simulated" time-lapse video, with artist's interpretation. Jupiter's clouds do not move at all during the video. Neither do Io's or Europa's terminators, while Jupiter's terminator approaches at the right.
No. The clouds of the Great Red Spot are clearly seen rotating clockwise, as well as the parallel movements of the white clouds further below
Alex
Erm, no, the Red Spot clouds don't clearly rotate at all. The caption uses the term "depicts" for good reason, Cover the moons with your hand and watch the background image very closely, marking point features. If you see movement you may need to see your optometrist. ;) ;) ;)
How much cloud movement would you expect to see? It takes more than four days for the red spot to complete one rotation, and this sequence was maybe on the order of an hour.
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johnnydeep
- Commodore
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Post
by johnnydeep » Wed Jun 14, 2023 8:35 pm
Chris Peterson wrote: ↑Wed Jun 14, 2023 4:31 am
pclark@bigpond.net.au wrote: ↑Wed Jun 14, 2023 4:20 am
alex555 wrote: ↑Tue Jun 13, 2023 7:52 am
No. The clouds of the Great Red Spot are clearly seen rotating clockwise, as well as the parallel movements of the white clouds further below
Alex
Erm, no, the Red Spot clouds don't clearly rotate at all. The caption uses the term "depicts" for good reason, Cover the moons with your hand and watch the background image very closely, marking point features. If you see movement you may need to see your optometrist.
How much cloud movement would you expect to see? It takes more than four days for the red spot to complete one rotation, and this sequence was maybe on the order of an hour.
So what's happening between an early frame from the video and a later frame shown in this side-by-side:
The inner dark patch certainly
seems to be rotating counter clockwise a little!
--
"To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}
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Chris Peterson
- Abominable Snowman
- Posts: 18490
- Joined: Wed Jan 31, 2007 11:13 pm
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by Chris Peterson » Wed Jun 14, 2023 8:57 pm
johnnydeep wrote: ↑Wed Jun 14, 2023 8:35 pm
Chris Peterson wrote: ↑Wed Jun 14, 2023 4:31 am
pclark@bigpond.net.au wrote: ↑Wed Jun 14, 2023 4:20 am
Erm, no, the Red Spot clouds don't clearly rotate at all. The caption uses the term "depicts" for good reason, Cover the moons with your hand and watch the background image very closely, marking point features. If you see movement you may need to see your optometrist. ;) ;) ;)
How much cloud movement would you expect to see? It takes more than four days for the red spot to complete one rotation, and this sequence was maybe on the order of an hour.
So what's happening between an early frame from the video and a later frame shown in this side-by-side:
red spot inner rotation cropped.jpg
The inner dark patch certainly
seems to be rotating counter clockwise a little!
No idea, but I don't think this sequence is long enough for there to be more than a few pixels of movement in any of the Jupiter cloud systems. Maybe something related to the tweening or whatever process was used to create a smooth video out of a limited number of frames?
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javachip3
Post
by javachip3 » Thu Jun 15, 2023 12:11 am
alex555 wrote: ↑Tue Jun 13, 2023 7:52 am
javachip3 wrote: ↑Tue Jun 13, 2023 5:23 am
This appears to be a "simulated" time-lapse video, with artist's interpretation. Jupiter's clouds do not move at all during the video. Neither do Io's or Europa's terminators, while Jupiter's terminator approaches at the right.
No. The clouds of the Great Red Spot are clearly seen rotating clockwise, as well as the parallel movements of the white clouds further below
Alex
Thanks! I agree, on closer inspection, the GRS rotates slightly counter-clockwise, and the white clouds at the bottom of the frame move leftward slightly faster than other features such as the white oval. As Chris suggests, it would be helpful to know the elapsed time from start to finish, and how many actual frames were recorded to produce this clip.