Mars white patch

[jetstream]

Last night I observed Mars under avg seeing or a bit worse at times.I am wondering what a white patch I saw in the middle,near the edge is.The 90mm gave some very good views, seeing and aperture condidered,very nice contrast.Is this white area permanent?

[Knight of Clear Skies]

Depending on the orientation, you are either looking at the polar cap or a cloud over its surface.

[John]

It's most likely an area called Hellas which has appeared very bright and white this opposition. It's a larger white patch than the N polar cap and the two can sometimes be confused. There have been some other smaller bright and pale spots on the Martian disk over the past few weeks as well. Some of these could be cloud cover.

[Knight of Clear Skies]

Hope my post wasn't misleading, I didn't realise there could be a light patch more visible than the polar cap.

[jetstream]

Thanks guys,it was very interesting.I could see both caps,with the little bright one at the top and the white patch on the right,in the middle-using a refractor.Amazing we can see this stuff,John I'll check out Hellas-thanks

[John]

..... I didn't realise there could be a light patch more visible than the polar cap.

Nor did I until this opposition. In previous ones the N polar cap has been the whitest spot on the planet. I wonder if Mars is having a colder spell at the moment and there is more frost around in other areas ?

[Knight of Clear Skies]

Nor did I until this opposition. In previous ones the N polar cap has been the whitest spot on the planet. I wonder if Mars is having a colder spell at the moment and there is more frost around in other areas ?

Could be, I found the latest Mars weather report here, which includes an animated globe with data from the Mars Reconnaissance Orbiter. It mentions " Surface frost was visible at southern high-latitudes. Diffuse water ice clouds related to the aphelion cloud belt were present at equatorial latitudes." However, it only goes up to the 27th of April, hopefully the next one will be posted in a day or two.

[Scooot]

http://stargazerslounge.com/topic/215906-mars-clearly-showing-elysium-mons/

Is that white patch Hellas at 2 O'clock in this image?

[Stu]

Hi Scooot,

No, Hellas is a larger white area almost opposite the polar cap. It's shown in this image/link.

http://stargazerslounge.com/index.php?/topic/215501-Mars%2C-April-22-from-Cyprus

Not sure what the cloud is in the image you posted, possibly a cloud over one if the mountains?

Cheers,

Stu

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[jetstream]

Great link Stu,I may have been calling Hellas a polar cap...if we take your link pic and add the white patch from scoots link pic,it is close to my obs-except it was bigger,brighter and more distinct.Is that a cloud or frost area then?You know up until recently I never knew Mars had an atmosphere.

[Pete Presland]

imaging Mars this spring has been quite an education (when the seeing allows!) regarding the atmosphere. so many clouds or colder areas visible especially in the blue channel

[Stu]

Hi Gerry,

My understanding is that Hellas is a massive impact basin caused during the heavy bombardment period. It is much lower than the surrounding areas and I believe it is either cloud or frosting or both contained within the basin as a result of it being winter in the Southern Hemisphere right now. We can't see the southern ice cap as it is turned away from us at the moment.

The location ties up with the previous image ie south-ish of Syrtis Major.

(Not sure where I got the second image from, possibly google images but possibly off the forum, my apologies for the lack of credit if it's anybody's on here.)

Wiki has more info and images showing the elevation changes here:

http://en.m.wikipedia.org/wiki/Hellas_Planitia

I also found these two links backing up the cloud/frosting theory. Here is a quote from the first link....

'Winter’s already well underway in the planet’s southern hemisphere and there’s no better place to see it than over Hellas, Mars’ biggest impact crater. Hellas formed some 4 billion years when a small asteroid crashed into the young planet and left a scar measuring 1,400 miles (2,300 km) wide and 26,465 feet (7,152 meters) deep. Point your telescope in its direction in the next few weeks and you’ll see what looks at first like the planet’s south polar cap. Don’t be deceived. That’s Hellas coated in dry ice frost and filled with wintertime clouds.'

http://www.universetoday.com/110279/till-hellas-freezes-over-see-frost-and-clouds-in-mars-largest-crater/

http://www.spaceweathergallery.com/indiv_upload.php?upload_id=95322

Hope that helps a little, I'm learning all the time :-)

Cheers,

Stu

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[cotterless45]

Well posted !

At best we've seen up to three bright areas in addition to the polar cap. It's not been at all easy, some of the best views being low with light cloud,

Nick.

[John]

Great post Stu 

My hunch was almost correct then.

[Stu]

Great post Stu

My hunch was almost correct then.

Thanks John. Yes, it looks that way, winter in Hellas. Sounds chilly! :-)

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[dweller25]

There are a lots of bright white patches on Mars at the moment....

The Polar cap is one but it is very small and hard to see.

Hellas is in the opposite hemisphere and is very large, bright and white and easy to confuse as a polar cap.

Elysium is between the two and is also showing as a pale white patch.

And both preceding and following limbs also show varying white areas.

[mjpfc]

There have been some bright clouds naer and above Tharsis and Olymp Mons this apparotion but also

around 16th 17th April there were decent sized patches of brightness at Eden and Aerta, either side of

the plains of Arabia, thes seen below Hellas and above the tiny sth cap (Newt Upside-down view).

I agreen with the guys above Hellas has ,this year, been brighter than I have ever seen it, its usually light

-yellowish but this apparition it is a knockout and makes the nth cap hard to make out above it.

Mick.