Europa Flyby - PJ45, September 29, 2022 |
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Europa Flyby - PJ45, September 29, 2022 |
 Sep 29 2022, 09:40 PM
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#46
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Solar System Cartographer  Group: Members Posts: 10166 Joined: 5-April 05 From: Canada Member No.: 227  |
"There seem to be two large but shallow north-south trending but broad 'troughs' roughly midway through the illuminated half of the disk"
These are real and part of a family of similar features on Europa which form interesting patterns. https://www.lpi.usra.edu/meetings/lpsc2005/pdf/2081.pdf https://agupubs.onlinelibrary.wiley.com/doi...29/2020GL088364 Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PD: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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Sep 29 2022, 10:09 PM
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#47
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Member Group: Members Posts: 144 Joined: 22-July 14 Member No.: 7220 |
Composite view using PJ45-2/3/4, projected to the perspective of PJ45-4
 Europa - PJ45-2/3/4 - Composite |
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Sep 29 2022, 10:23 PM
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#48
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 Member Group: Members Posts: 555 Joined: 27-September 10 Member No.: 5458 |
QUOTE (volcanopele @ Sep 29 2022, 04:37 PM)  ehhh, there might some hints at Jupiter shine, but ehhh, it isn't much: Using the image Brian had posted, you can definitely identify some continuing features.
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Sep 29 2022, 11:32 PM
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#49
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 Senior Member Group: Members Posts: 1639 Joined: 5-March 05 From: Boulder, CO Member No.: 184 |
A rough idea comparing Kevin's composite to a prior Galileo/Voyager map that combines Bjorn's mapping and a USGS map.
-------------------- Steve [ my home page and planetary maps page ]
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Sep 30 2022, 08:57 AM
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#50
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 Member Group: Members Posts: 810 Joined: 3-June 04 From: Brittany, France Member No.: 79 |
My take on one of those fantastic Europa pictures.
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Sep 30 2022, 06:12 PM
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#51
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Member Group: Members Posts: 411 Joined: 18-September 17 Member No.: 8250 |
Has a blue atmosphere on Europa been imaged by Galileo (or any other observation)?
(I'm haven't convinced myself yet, that it is real. But the uniformity across multiple framelets prevents me from immediately dismissing it as a processing artifact.)
The full resolution PNG for PJ45_01 from which this is cropped is at https://www.missionjuno.swri.edu/junocam/processing?id=13834 |
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Sep 30 2022, 06:14 PM
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#52
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 Member Group: Members Posts: 754 Joined: 9-February 07 Member No.: 1700 |
QUOTE (scalbers @ Sep 29 2022, 03:32 PM) A rough idea comparing Kevin's composite to a prior Galileo map that combines Bjorn's mapping and a USGS map.
Answering a few of my amateur space fan questions, thanks!! |
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Sep 30 2022, 06:33 PM
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#53
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 Senior Member Group: Moderator Posts: 3233 Joined: 11-February 04 From: Tucson, AZ Member No.: 23 |
Now that I got the geometry how I want (and Bjorn is right, correcting the geometry was MUCH easier this time around compared to Ganymede), starting working on the photometry.
-------------------- &@^^!% Jim! I'm a geologist, not a physicist!
The Gish Bar Times - A Blog all about Jupiter's Moon Io |
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Sep 30 2022, 06:53 PM
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#54
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Senior Member Group: Members Posts: 2998 Joined: 30-October 04 Member No.: 105 |
QUOTE (antipode @ Sep 29 2022, 04:11 PM) Fantastic relief details near the terminator! There seem to be two large but shallow north-south trending but broad 'troughs' roughly midway through the illuminated half of the disk. Are these real, or just imaging artifacts? P They are likely real. There is third short trough, overprinted to the North, between those two and the terminator. And on the terminator, a line of lineations. I'm thinking that these are old tectonic features, softened and broadened with age. My guess. --Bill -------------------- |
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Sep 30 2022, 07:52 PM
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#55
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Member Group: Members Posts: 144 Joined: 22-July 14 Member No.: 7220 |
I would attribute that more to chromatic aberration. Europa doesn't have an appreciable atmosphere that I'm aware of.
QUOTE (Brian Swift @ Sep 30 2022, 02:12 PM) Has a blue atmosphere on Europa been imaged by Galileo (or any other observation)? (I'm haven't convinced myself yet, that it is real. But the uniformity across multiple framelets prevents me from immediately dismissing it as a processing artifact.)
The full resolution PNG for PJ45_01 from which this is cropped is at https://www.missionjuno.swri.edu/junocam/processing?id=13834 |
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Sep 30 2022, 09:13 PM
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#56
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Senior Member Group: Members Posts: 2998 Joined: 30-October 04 Member No.: 105 |
QUOTE (Kevin Gill @ Sep 30 2022, 02:52 PM) I would attribute that more to chromatic aberration. Europa doesn't have an appreciable atmosphere that I'm aware of. Chromatic aberration? Would a rotating pushbroom be prone to that? We don't see a red-fringe on the opposite night terminator side of the assembled image. Have we seen blue (red) fringes before? -------------------- |
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Sep 30 2022, 10:39 PM
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#57
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 Member Group: Members Posts: 700 Joined: 3-December 04 From: Boulder, Colorado, USA Member No.: 117 |
99.9% chance that it's an artifact, due to misregistration of some kind. Certainly nothing real like that has ever been seen on Europa, and the atmosphere is much too thin to show up in visible light.
John |
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Sep 30 2022, 10:47 PM
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#58
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Senior Member Group: Members Posts: 2517 Joined: 13-September 05 Member No.: 497 |
QUOTE (Bill Harris @ Sep 30 2022, 01:13 PM) Chromatic aberration? Would a rotating pushbroom be prone to that? We don't see a red-fringe on the opposite night terminator side of the assembled image. Have we seen blue (red) fringes before? FWIW, Junocam is not a pushbroom. There certainly shouldn't be any significant chromatic aberration, but there are plenty of ways for different color framelets to get misregistered, and that's probably more likely the farther you go from the optic axis. So I agree with John. -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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Oct 1 2022, 12:33 AM
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#59
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 IMG to PNG GOD Group: Moderator Posts: 2251 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
This is image PJ45_2:
The color is probably more accurate than the color in the 'quick and dirty' PJ45_1 image I posted yesterday. North is up. I have also seen small amounts of blue at Europa's limb but it is only present at maybe 10-20% of the limb (very rough guess). It's definitely not a real feature, the 'atmosphere' of Europa is far too thin to be visible, especially when the phase angle isn't very high. There are lots of ways for the color channels to get slightly misaligned as Mike pointed out. |
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Oct 1 2022, 12:44 AM
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#60
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Senior Member Group: Moderator Posts: 3233 Joined: 11-February 04 From: Tucson, AZ Member No.: 23 |
Here are photometrically corrected versions of the other three images:
-------------------- &@^^!% Jim! I'm a geologist, not a physicist!
The Gish Bar Times - A Blog all about Jupiter's Moon Io |
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