Mars rovers provide another perspective on farside solar activity

[Newbie]

This is the abstract from the publication mentioned below.

Space weather events, including active regions on the Sun responsible for significant and potential space weather, have been monitored from Earth and space. However, this coverage does not generally include all longitudes of the Sun at any given time. Serendipitously, images from the Mars rovers show sunspots and can supplement traditional solar imaging. The Perseverance rover on Mars carries the Mastcam-Z stereo camera, which has the potential for monitoring sunspots from a Mars vantage point. Color and monochrome (880-nm) solar images were taken using neutral density filters that allow solar imaging. Images were taken with the primary purpose of monitoring the direct flux at the surface and thus determining the time-variable aerosol load of the atmosphere via extinction. The 67 microradian pixel size corresponds to 15,000 km on the Sun, a very low resolution compared to purpose-built solar cameras. However, it can detect >40% of sunspots and resolve the largest 5-10% of spot umbras. In addition, the Curiosity rover has a nearly 10-year record of 440-nm solar images at a somewhat lower resolution that still detects the largest active areas. We will present a catalog of the sunspot record as observed from Mars. We shall also discuss the following: 

Dates for which another asset can validate the observations;Times for which Mars had a unique vantage and thus provide data that might be useful for localizing space weather events or validating models of farside activity (e.g., from helioseismology);Prospects for future monitoring of regions of the Sun that are about to become Earth-facing when Mars has a unique vantage (e.g., several months during 2023 and 2025). 

Publication:

American Astronomical Society Meeting #241, id. 265.03. Bulletin of the American Astronomical Society, Vol. 55, No. 2 e-id 2023n2i265p03

Pub Date:January 2023

The image below shows the Earth facing magnetogram on the right, the farside Helioseismology image on the left and inset the image provided by the Perserverance rover on Mars (courtesy of Spaceweather.com) It features two sunspots labelled #1 and #2 from Helioseismology images produced on July 18 and sunspots observed by the Perserverance rover.
Sunspot #2 is of particular interest because it is a large group and contains at least three large cores. This should turn into view in the next week according to the website.

Since the loss of the Stereo B satellite in 2014 there has been limited direct monitoring of the farside of the Sun.

As mentioned above such monitoring can validate farside models. Quite an achievement.

N.

[Sapphire828]

Hi Newbie, 

Is there a full paper that can be accessed online? Following the title I can only find the abstract. Maybe it was just a presentation and hasn't been published yet? 

I've been keeping an eye on the Mars Perseverance pictures and there are currently some decent sized sunspots. I'd like to figure out a way to rotate the rover images and estimate the time til it reaches the limb and visible from Earth.

[Newbie]

Hi @Sapphire828 thanks for the question.

 I believe the article was prepared as a news bulletin release. It has been published by a few other news outlets.
There was an earlier paper regarding the commissioning of the Mars Curiosity rover back in 2012 which has since been updated. Part of it’s future commission was to monitor far side sunspots looking for those that were potentially hazardous and may cause problems when they were geo-effective, not dissimilar to the one that was unleashed in 2012, the CME narrowly missing the Earth and was likened to a possible Carrington event.

https://science.nasa.gov/science-news/science-at-nasa/2014/23jul_superstorm

https://link.springer.com/article/10.1007/s11214-022-00882-7

Here is an overview of the brief for the Perseverance rover. Presented as a news story. https://www.rmg.co.uk/stories/topics/mars-nasa-rover-perseverance-facts-dates

The models that produce far side maps are validated by the observations of the Mars rovers.

https://mars.nasa.gov/mars2020/multimedia/raw-images/

Some of the  raw images are pretty good if you scroll back through them. Sunspots take around thirteen and a half days to transit the far side of the sun. I’m not sure about rotating the images. The schedule for Perseverance would likely change every day as well.

N.

[Newbie]

Setting sun from Mars. This is a raw pic, resolution not so great but still pretty amazing considering where it came from. 

Edited August 19 by Newbie
Extra information

[MinYoongi]

Thank you! A very interesting read! 

[Newbie]

https://www.cnbctv18.com/science/nasa-perseverance-rover-discovers-expanding-sunspot-know-potential-impact-on-earth-17601691.htm#:~:text=By CNBCTV18.com Aug 22,%3A55 PM IST (Updated)&text=NASA's Perseverance rover has made,currently displaying signs of expansion.

There are reports that a large sunspot group is heading our way next week. This was detected by NASA’s Mars Perseverance rover that was mapping a crater. The NASA report is dated 22 Aug. 

The Daily Mail (UK) reported this today 23 Aug in a rather sensational article warning its activity could knock out power grids. It’s currently doing the rounds however NASA takes a more measured approach.

N.

Edited August 23 by Newbie
Pic added

[Philalethes]

12 hours ago, Newbie said:

https://www.cnbctv18.com/science/nasa-perseverance-rover-discovers-expanding-sunspot-know-potential-impact-on-earth-17601691.htm#:~:text=By CNBCTV18.com Aug 22,%3A55 PM IST (Updated)&text=NASA's Perseverance rover has made,currently displaying signs of expansion.

There are reports that a large sunspot group is heading our way next week. This was detected by NASA’s Mars Perseverance rover that was mapping a crater. The NASA report is dated 22 Aug. 

The Daily Mail (UK) reported this today 23 Aug in a rather sensational article warning its activity could knock out power grids. It’s currently doing the rounds however NASA takes a more measured approach.

N.

Yep, looks like it was referring to those same August 20 images that I mentioned; still very cool to use imagery from Mars in lieu of satellite coverage, but obviously with some limitations in terms of image quality.

After cross-referencing various sky maps with the stars as seen on LASCO C3, which I believe to be oriented to the Solar equator like most other imagery, I believe this is a rough estimate of the corresponding orientation from Mars:

From there the Solar equator would also be curving slightly upward, so I estimate the spot(s) to be at around 20-25S. The rotational period at that latitude is very close to 26 days, and given the angular separation between Earth and Mars of ~135° it should take around 1/8 of that time (45° of rotation) before the spots start coming into view from an Earth-aligned perspective, assuming the spots are very close to the central meridian as seen from Mars (which appears to be the case); that would in other words be 3.25 days (3 days and 6 hours) from when the images were taken, which for the image I used as reference was 08-20T13:37Z, i.e. we'd expect to start seeing it around 08-23T19:37Z, which is just ~8 hours from now. From the above image the spot(s) seems to be a bit behind the central meridian though, just ~5 degrees would be another ~8 hours, so I'd ultimately estimate that we'll start seeing it within 24 hours.

Those are of course all rough estimates, and some of my assumptions could definitely be wrong, but that's what I'd go with: we'll start seeing it within 24 hours. Now watch reality prove me wrong.

Addendum:

Decided to double-check using an online protractor, here's an image with the aligned angles; green is the angle between the horizontal line through C3 and the closest bright star I could identify (Nu Leonis), and blue and red the corresponding horizontal and vertical equivalent respectively, i.e. red would be the central meridian:

Edited August 23 by Philalethes
added image with protractor

[tniickck]

15 minutes ago, Philalethes said:

Yep, looks like it was referring to those same August 20 images that I mentioned; still very cool to use imagery from Mars in lieu of satellite coverage, but obviously with some limitations in terms of image quality.

After cross-referencing various sky maps with the stars as seen on LASCO C3, which I believe to be oriented to the Solar equator like most other imagery, I believe this is a rough estimate of the corresponding orientation from Mars:

From there the Solar equator would also be curving slightly upward, so I estimate the spot(s) to be at around 20-25S. The rotational period at that latitude is very close to 26 days, and given the angular separation between Earth and Mars of ~135° it should take around 1/8 of that time (45° of rotation) before the spots start coming into view from an Earth-aligned perspective, assuming the spots are very close to the central meridian as seen from Mars (which appears to be the case); that would in other words be 3.25 days (3 days and 6 hours) from when the images were taken, which for the image I used as reference was 08-20T13:37Z, i.e. we'd expect to start seeing it around 08-23T19:37Z, which is just ~8 hours from now. From the above image the spot(s) seems to be a bit behind the central meridian though, just ~5 degrees would be another ~8 hours, so I'd ultimately estimate that we'll start seeing it within 24 hours. 

you are not wrong, i guess, we can see strong bright coronal loops behind the limb

[Hagen72]

In german website from T- online they wrote NASA is warning.

Ich habe einen spannenden Artikel gefunden. https://www.t-online.de/digital/aktuelles/id_100230106/riesiger-sonnensturm-die-erde-fliegt-genau-ins-schussfeld.html

[hamateur 1953]

https://sdo.gsfc.nasa.gov/assets/img/latest/latest_1024_0131.jpg  I have also been watching SDO 48hr run in 131 angstroms. Lots of fireworks beyond the limb presently. 

Edited August 23 by hamateur 1953
Added link at top

[tniickck]

9 minutes ago, hamateur 1953 said:

https://sdo.gsfc.nasa.gov/assets/img/latest/latest_1024_0131.jpg  I have also been watching SDO 48hr run in 131 angstroms. Lots of fireworks beyond the limb presently. 

yeah we might face one of the biggest of the cycle hopefully

[Sapphire828]

@Philalethes Thanks! This is exactly what I was thinking of when I revived the post last week.

The rover is slacking, it would be nice to see one more picture from the rover before the spot comes over the limb to refine the angles and orientation. 

[tniickck]

Well i see something on the limb that looks like a spot but i am probably glitching

[Philalethes]

1 hour ago, Sapphire828 said:

@Philalethes Thanks! This is exactly what I was thinking of when I revived the post last week.

The rover is slacking, it would be nice to see one more picture from the rover before the spot comes over the limb to refine the angles and orientation. 

Yeah, without knowing the orientation of the camera the only way I can think of is to use stars for reference.

One thing I didn't mention in the post was how it was complicated one step further by the fact that I struggled to find any reliably recognizable stars common to both C3 and Mastcam, so I had to identify one from each separately (Regulus for C3 in this case) and reference a third view found in sky maps of the angle between the two at that time. Then you can just subtract that angle from the angle between C3 horizontal and the C3 reference star, and you get the angle between the Mastcam reference star and C3 horizontal, which in this case was ~6° (hence why the protractor has the green line running through it there).

Of course, if you find a common reference star between the two you can skip that additional step, because you get that angle immediately.

Another thing to note that I didn't account for is that we're currently nearing the time when there's Solar tilt directly towards us (so while the Solar equator would curve slightly upward in the Mastcam images, it would curve maximally downward for us, as you can see on e.g. the Solarsoft website. This actually means that some degrees of longitude near the limb in the southern hemisphere are hidden from view (and correspondingly that we can see an equal amount of extra degrees of longitude beyond 90° in the northern hemisphere). Looking at it now the first 10 degrees of longitude at around 20-25S are half hidden and half squashed into a tiny sliver that isn't particularly well visible. That alone is possibly another additional 17 hours, although I'd still assume we'd see signs of it before then, unless there's some serious flaw somewhere in what I'm calculating.

This thing has been hyped up a lot at this point, usually difficult to live up to, but we'll see soon.

[Newbie]

4 minutes ago, Philalethes said:

Yeah, without knowing the orientation of the camera the only way I can think of is to use stars for reference.

One thing I didn't mention in the post was how it was complicated one step further by the fact that I struggled to find any reliably recognizable stars common to both C3 and Mastcam, so I had to identify one from each separately (Regulus for C3 in this case) and reference a third view found in sky maps of the angle between the two at that time. Then you can just subtract that angle from the angle between C3 horizontal and the C3 reference star, and you get the angle between the Mastcam reference star and C3 horizontal, which in this case was ~6° (hence why the protractor has the green line running through it there).

Of course, if you find a common reference star between the two you can skip that additional step, because you get that angle immediately.

Another thing to note that I didn't account for is that we're currently nearing the time when there's Solar tilt directly towards us (so while the Solar equator would curve slightly upward in the Mastcam images, it would curve maximally downward for us, as you can see on e.g. the Solarsoft website. This actually means that some degrees of longitude near the limb in the southern hemisphere are hidden from view (and correspondingly that we can see an equal amount of extra degrees of longitude beyond 90° in the northern hemisphere). Looking at it now the first 10 degrees of longitude at around 20-25S are half hidden and half squashed into a tiny sliver that isn't particularly well visible. That alone is possibly another additional 17 hours, although I'd still assume we'd see signs of it before then, unless there's some serious flaw somewhere in what I'm calculating.

This thing has been hyped up a lot at this point, usually difficult to live up to, but we'll see soon.

Very interesting work @Philalethes 

It is very difficult to calculate an exact appearance of the sunspot earth side due to the angle of incidence of light  hitting the surface of Mars, the orientation of the rover at the time.
In addition The synodic rotation of Mars is Solar Martian day being 24.6 hours further complicates matters. The inclination as well as you mention north to south is another factor as you point out.

Also up until now there has not been anything else from Mastcam as @Sapphire828 points out.

Re the hype, yeah I could see where it was headed, so I tried to downplay it as much as possible. There haven’t been any earth side effects as far as I can discern up until now.

Good work.

N.

[Philalethes]

1 hour ago, Newbie said:

Very interesting work @Philalethes 

It is very difficult to calculate an exact appearance of the sunspot earth side due to the angle of incidence of light  hitting the surface of Mars, the orientation of the rover at the time.
In addition The synodic rotation of Mars is Solar Martian day being 24.6 hours further complicates matters. The inclination as well as you mention north to south is another factor as you point out.

Also up until now there has not been anything else from Mastcam as @Sapphire828 points out.

Re the hype, yeah I could see where it was headed, so I tried to downplay it as much as possible. There haven’t been any earth side effects as far as I can discern up until now.

Good work.

N.

It would definitely complicate matters a lot if you were trying to calculate all of this just from knowledge of the position of the rover and time, but the main point of orienting the image so you get the Solar equator horizontal like in all the other imagery is of course so that you don't need to account for any of that, since you're deriving that correct orientation using the stars. Otherwise it'd really be hard, especially given the fact that the camera itself can always be oriented in an arbitrary manner (e.g. you could easily take photos of Sol here from Earth in any orientation you'd like by simply rotating the camera).

And yeah, sadly no new and updated imagery, would have been great to have not just as a general update but also so that I could have cross-referenced what I did above using that. It's certainly very possible that there are some assumptions I've made that are incorrect, but after going over it a couple of times I think it should be roughly right. There is yet another thing to account for of course, as I'm thinking about it more to try to make my guess even more precise, and that is the orbital speed of Earth, which means we're moving ~1 degree per day from that.

So, if we try to refine the initial guess by accounting for all of this, I don't think the spot(s) were more than just a couple of degrees from the central meridian from looking at a quick overlay, so by taking that and adding an additional 4 degrees to compensate for an estimate of the longitudes that are out of view due to the Solar tilt, and then adding another 4 degrees for the orbital movement as we're heading into the 24th, that's a total of 10 more degrees, so another 1/36 of those ~26 days, which as mentioned above (albeit not for the exact same reason) comes out to ~17 hours. Ironically this puts the total estimate from the previous time at 25 hours, more than within 24 hours as I suggested first, but that's part of the fun of doing these calculations of course.

But yeah, going by all of that, let's say 08-24T14:37Z is a more realistic estimate for when it starts to become visible, i.e. in around 11-12 hours from now. Of course trying to get these things exactly right is probably futile, but it's a fun little exercise, and science is of course about trying to get predictions as accurate as possible, heh.

Edited August 24 by Philalethes
grammar

[Newbie]

1 hour ago, Philalethes said:

It would definitely complicate matters a lot if you were trying to calculate all of this just from knowledge of the position of the rover and time, but the main point of orienting the image so you get the Solar equator horizontal like in all the other imagery is of course so that you don't need to account for any of that, since you're deriving that correct orientation using the stars. Otherwise it'd really be hard, especially given the fact that the camera itself can always be oriented in an arbitrary manner (e.g. you could easily take photos of Sol here from Earth in any orientation you'd like by simply rotating the camera).

And yeah, sadly no new and updated imagery, would have been great to have not just as a general update but also so that I could have cross-referenced what I did above using that. It's certainly very possible that there are some assumptions I've made that are incorrect, but after going over it a couple of times I think it should be roughly right. There is yet another thing to account for of course, as I'm thinking about it more to try to make my guess even more precise, and that is the orbital speed of Earth, which means we're moving ~1 degree per day from that.

So, if we try to refine the initial guess by accounting for all of this, I don't think the spot(s) were more than just a couple of degrees from the central meridian from looking at a quick overlay, so by taking that and adding an additional 4 degrees to compensate for an estimate of the longitudes that are out of view due to the Solar tilt, and then adding another 4 degrees for the orbital movement as we're heading into the 24th, that's a total of 10 more degrees, so another 1/36 of those ~26 days, which as mentioned above (albeit not for the exact same reason) comes out to ~17 hours. Ironically this puts the total estimate from the previous time at 25 hours, more than within 24 hours as I suggested first, but that's part of the fun of doing these calculations of course.

But yeah, going by all of that, let's say 08-24T14:37Z is a more realistic estimate for when it starts to become visible, i.e. in around 11-12 hours from now. Of course trying to get these things exactly right is probably futile, but it's a fun little exercise, and science is of course about trying to get predictions as accurate as possible, heh.

Yeah it’s a lot of fun working it all out but severely hampered by lack of data. It’s a starting point though isn’t it. At least when the active region finally comes into view we will have a better understanding of how these these things work. 
One other thing to be mindful of is the "Mars sunset illusion," where the Sun appears larger and more oval-shaped during sunset than it does when it's high in the sky. This effect occurs due to the scattering of light in the Martian atmosphere. Perhaps it’s not an issue at this time but something to consider in the future depending on what pics are available.

N.

[Aten]

You guys sure those two spots on the image aren't AR 3413 and 3415? Because that's what it looks like to me, with the solar equator roughly vertical in the image. I guess we'll find out soon.

[Newbie]

2 hours ago, Aten said:

You guys sure those two spots on the image aren't AR 3413 and 3415? Because that's what it looks like to me, with the solar equator roughly vertical in the image. I guess we'll find out soon.

Hi there @Aten 3413 was attributed its number on 21 August and 3415 on 22 August. Both active regions were partially visible on the  E limb of the Sun (Earthside) for a time before they rotated fully into view and were numbered and classified.

The earliest available pic we have to work with from the Mars rover was dated 20 August and at the time the active region was still almost centre a fair way from the limb (Mars Rover view).

Refer to the earlier pics in the threads.

N.

Edited August 24 by Newbie
Edited for clarity. Sorry for confusion

[Aten]

5 hours ago, Philalethes said:

One thing I didn't mention in the post was how it was complicated one step further by the fact that I struggled to find any reliably recognizable stars common to both C3 and Mastcam, so I had to identify one from each separately (Regulus for C3 in this case) and reference a third view found in sky maps of the angle between the two at that time. Then you can just subtract that angle from the angle between C3 horizontal and the C3 reference star, and you get the angle between the Mastcam reference star and C3 horizontal, which in this case was ~6° (hence why the protractor has the green line running through it there).

Those aren't stars in the mastcam images. You can't see stars when the sun is out!

[tniickck]

one of the biggest of the cycle we thought... it might have been miscalculation though, so waiting and watching

[Philalethes]

6 hours ago, Aten said:

You guys sure those two spots on the image aren't AR 3413 and 3415? Because that's what it looks like to me, with the solar equator roughly vertical in the image. I guess we'll find out soon.

Based on the orientation from looking at the stars, that's not possible in my view. If you look at the original Mastcam imagery and C3 from the same day, you should be able to make out Nu Leonis and Regulus (Alpha Leonis) respectively without too much problem, which at the time the images were taken both extended out almost radially from the center of the disc (with only ~1-2° degrees of difference in the angle). This yields a Solar equator roughly along the lines of what I posted in the images above. You are of course free to repeat the procedure for yourself and see if you conclude differently.

5 hours ago, Aten said:

Those aren't stars in the mastcam images. You can't see stars when the sun is out!

Yes, they are very clearly stars. You can in fact see several recognizable star formations that you can identify on a star map. Due to the smaller amount of sunlight and the thinner atmosphere it's presumably easier to capture the stars even during the day if you use varying amounts of exposure, I assume the image is a composite between lower exposure of the Solar disc and higher exposure to get the surrounding stars.

Edited August 24 by Philalethes

[Aten]

31 minutes ago, Philalethes said:

Yes, they are very clearly stars. You can in fact see several recognizable star formations that you can identify on a star map. Due to the smaller amount of sunlight and the thinner atmosphere it's presumably easier to capture the stars even during the day if you use varying amounts of exposure, I assume the image is a composite between lower exposure of the Solar disc and higher exposure to get the surrounding stars.

I'm 99.99% sure this is complete nonsense. I am not a photographer or a scientist, but from what I know I have a very hard time believing you could ever capture stars and sunspots in the same image. Keep in mind this camera was meant to take pictures of rocks and dirt not do astronomy.

And even if you had a coronagraph in orbit around mars, the stars that appeared to be near the sun would be completely different than the stars in the SOHO images because the two coronagraphs would be looking out into our galaxy in different directions.

[Philalethes]

5 minutes ago, Aten said:

I'm 99.99% sure this is complete nonsense. I am not a photographer or a scientist, but from what I know I have a very hard time believing you could ever capture stars and sunspots in the same image. Keep in mind this camera was meant to take pictures of rocks and dirt not do astronomy.

And even if you had a coronagraph in orbit around mars, the stars that appeared to be near the sun would be completely different than the stars in the SOHO images because the two coronagraphs would be looking out into our galaxy in different directions.

Well, that latter point is actually a great one, I had failed to consider that at all; that's definitely a rudimentary failure of basic astronomy on my part. Given that fact it's clear that all my analysis is void in this case. That also means I must have been matching similar individual star formations without referencing the entire image; that's a good reminder to use a complete overlay the next time I try matching up images like this, although it's obvious from the above point that something extra needs to be done to reference a different position in the orbit (further complicated by the fact that Earth and Mars don't follow the exact same orbits).

I still do suspect that they are in fact stars, but your point certainly casts doubt on that too. I know that with the right equipment and under the right conditions you can capture stars even during the day here on Earth where sunlight is much brighter and the atmosphere much thicker, so presumably you could still make a composite as described (low exposure to capture the Solar disc and sunspots, high exposure for the surrounding stars).

Thanks for uncovering that basic mistake, apologies for coming off as more certain than I had any right to be. I will try to look at some imagery from Mars using Stellarium now to see if I can make out the orientation using the ecliptic instead.

[Sapphire828]

I was under the impression that the colored dots in the background were dead pixels or issues with the camera sensor. If they are consistent, maybe they could be used to discern the orientation of the camera when the photo was taken?