Mars rovers provide another perspective on farside solar activity

[Jesterface23]

We don't know when the images are taken as well currently. Only when they are received.

[hamateur 1953]

14 hours ago, Jesterface23 said:

We don't know when the images are taken as well currently. Only when they are received.

A very good point! No timestamps accompanying them. Although one way radio communication should only be 45 min or so a days delay in processing would be significant. 

[Philalethes]

20 minutes ago, hamateur 1953 said:

one way radio communication should only be 45 min or so

I think that's two-way, and at maximum separation between the planets, one-way should be roughly 3 to 22 minutes depending on separation.

But whatever delays happen along the pipeline is indeed hard to know. On the website it just says "acquired" at this and that time, which does indeed sound like it's not necessarily when it was taken. Would be nice of NASA to clarify and to add the actual time it was taken if it's not already.

[hamateur 1953]

True except I hear Elon is working on superluminal communication, which  will render all of these discussions academic soon... ( jk) 

7 hours ago, Philalethes said:

I think that's two-way, and at maximum separation between the planets, one-way should be roughly 3 to 22 minutes depending on separation.

But whatever delays happen along the pipeline is indeed hard to know. On the website it just says "acquired" at this and that time, which does indeed sound like it's not necessarily when it was taken. Would be nice of NASA to clarify and to add the actual time it was taken if it's not already.

Edited January 22 by hamateur 1953
Typo

[Sapphire828]

Found something nice! Sol 1037, this past weekend it looks like the rover captured images of another solar eclipse.

I've compressed the picture here quite a bit, but in the full resolution pictures from the website you can see a sunspot on the solar disk as well.

There's about 176 pictures taken about 1 second apart for a total of 2 minutes and 15 seconds.

I was initially hopeful the angle and path the moon takes (Deimos?) could be used to infer the sun's orientation, but again there's no information about the direction the rover was facing...

@Jesterface23 brought up we don't have any timestamps of when the photos were taken, but these could be used to determine the "Mars time" if there is external info about the eclipse at the crater's location.

@Philalethes with the "continuous capture" and assuming the rover was still during the observation, the sunspot direction over the short period of time might be able to be used to infer the sun's orientation.

Lots to unpack here and unfortunately I'm pretty busy at work this week or else I would give it a shot myself.

-EM

Edited January 23 by Sapphire828

[Philalethes]

On 1/23/2024 at 5:29 AM, Sapphire828 said:

Found something nice! Sol 1037, this past weekend it looks like the rover captured images of another solar eclipse.

I've compressed the picture here quite a bit, but in the full resolution pictures from the website you can see a sunspot on the solar disk as well.

There's about 176 pictures taken about 1 second apart for a total of 2 minutes and 15 seconds.

I was initially hopeful the angle and path the moon takes (Deimos?) could be used to infer the sun's orientation, but again there's no information about the direction the rover was facing...

@Jesterface23 brought up we don't have any timestamps of when the photos were taken, but these could be used to determine the "Mars time" if there is external info about the eclipse at the crater's location.

@Philalethes with the "continuous capture" and assuming the rover was still during the observation, the sunspot direction over the short period of time might be able to be used to infer the sun's orientation.

Lots to unpack here and unfortunately I'm pretty busy at work this week or else I would give it a shot myself.

-EM

Very cool picture; I guess it's more commonly considered a transit of Deimos rather than an eclipse due to how small Deimos is, but there's ultimately no strict boundary between a transit and a partial eclipse I guess, heh.

If you have access to the full path Deimos takes across the Solar disc you should be able to infer the orientation of the image with respect to the Solar equator regardless of the orientation of the rover (just like multiple images of the same sunspots moving across the disc would allow you to see the Solar equator more or less directly). You don't even really need the rover to stand still between such images, as long as you can identify the same features in each image (and with Deimos that would of course be quite easy, but in this case it seems the rover did indeed stand still).

In fact, here I've plugged in a view from the current location of Perseverance into Stellarium, with a line showing the projected Solar equator, so that we can see quite easily where the Solar equator is relative to Deimos' path, Solar equator being the red line and path of Deimos being the black line:

A couple of things to note:

1.  I think the path is a little bit more off center in the actual imagery, probably because the actual coordinates are slightly off; the direction across the disc should still be the same anyway, so the angle relative to the Solar equator should also be the same.
    
2. The sunspots on the disc in Stellarium don't correspond to anything real, it's just there for aesthetic purposes.

And yeah, the point about the timestamps is also good; on the website it says the first images were acquired around 08:42, while the transit started around 01:32 according to Stellarium, which indicates ~7 hours of delay in this particular case, can't say whether that's typical or not though.

[Sapphire828]

Nice! This is exactly what I though could be done. Thanks for the animation. This is why the 90 degree rotation works as a decent approximation since the solar equator is close to vertical.

After looking more into the timestamps, I am even more confused. I don't think I'm ready to think about timekeeping on different planets. 😧
https://en.wikipedia.org/wiki/Timekeeping_on_Mars

[Sapphire828]

Transit of Phobos captured by the rover this week: Sol 1056 (Feb. 8th, 2024)

There's about 65 pictures taken about 0.5-1 seconds apart.
Transit starts ~06:29:16 mean solar time according to the timestamp on the first picture.

@Philalethes If you get a chance, could you check the orientation of the solar equator again and compare times like you did in the previous post? thanks

[Philalethes]

10 hours ago, Sapphire828 said:

Transit of Phobos captured by the rover this week: Sol 1056 (Feb. 8th, 2024)

There's about 65 pictures taken about 0.5-1 seconds apart.
Transit starts ~06:29:16 mean solar time according to the timestamp on the first picture.

@Philalethes If you get a chance, could you check the orientation of the solar equator again and compare times like you did in the previous post? thanks

Yeah, I actually noticed it when looking at some of the images after someone posted an image a few days ago. The angle between the transit and the Solar equator seems to be roughly the same: