What colour is Mercury, really?

General physics and astronomy discussions not directly related to Celestia
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Evil Dr Ganymede
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What colour is Mercury, really?

Post #1by Evil Dr Ganymede » 12.04.2004, 23:34

...and don't say "silver", I'm talking about the planet here! ;) :P

I'm pretty sure it's not that light tan/dark brown colour it is in Celestia. Thing is, I've only ever seen greyscale images of it, and I don't know what colour filters are available. Does it even have any colour at all, other than light/dark grey?

There are some updated Mariner 10 images at
http://www.psrd.hawaii.edu/Jan97/MercuryUnveiled.html

But the only colour images there are false colour mineral maps, which isn't very useful.

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Post #2by granthutchison » 13.04.2004, 00:15

Well, here's someone from a reputable university who says it really is orange: http://www.bk.psu.edu/faculty/cooper/solarsystem/mercury.html.
(Well, actually, it's his ten-year-old kid who made the webpage ...)

The general opinion seems to be that Mercury is like the Moon in colour and albedo. I kind of hoped that Fridger would eventually come up with a 1k version of his Mercury texture that he was happy to let out into the world, so I've been stalling around on this one for ages, but I don't think it's ever going to happen. :cry:
So it's really well past time to greyscale the existing texture, if nothing else.

Grant

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Post #3by Evil Dr Ganymede » 13.04.2004, 01:18

Yeah, grey would be my bet too.

Ditto for Venus. Though an accurate Venus surface texture would be extremely cool - not the orange SAR radar map, but what the surface would really look like.

I think that mostly it'd be black and grey (though I don't know if the temperature is high enough to make the ground glow red) because of all the basalts, but the highlands could be silvery in colour as they'd be capped by metal frosts deposited at altitude! "Pancake domes" may be paler in colour, since it sounds like they're more granitic in composition. Actually, come to think of it, the surface rocks might be a bit more like gabbro (still black, but with bigger crystals than basalt) since it takes longer for the rock to cool down in the high temperature?

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Post #4by granthutchison » 13.04.2004, 01:45

Evil Dr Ganymede wrote: ... though I don't know if the temperature is high enough to make the ground glow red ...
Not noticeably - it's about 450C, and things aren't reckoned to develop a faint red glow until 500C.
The orange colours of the radar maps are apparently sampled from the Venera photos - what you're seeing there is the surface illuminated by an orange glow filtering through the overcast. If the short wavelengths really are heavily trimmed, you might never be able to see the surface as anything but orange, without the use of a floodlight - like living in a permanent sunset.

Grant

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Post #5by tony873004 » 14.04.2004, 20:07

Mercury certainly has an orange tint when looking at it in real life, even when it is high enough to avoid being tinted by our atmosphere. Mercury just made an awesome apparition in the evening sky, and it got quite high by Mercury standards. It definately had an orange tint, but different than Mars'. As it sets, it gets redder from our atmosphere. But when Venus and Jupiter are at the same altitude, they both still have their white color. They don't start turning red until they're about 5 degrees from the horizon. Mercury has its orange tint much higher than this, implying that our atmosphere is not fully responsible for its orange tint. Of course things can still be deceiving. I've heard that our Moon is charcoal black, but it seems bright grey.

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Post #6by t00fri » 14.04.2004, 21:17

granthutchison wrote:Well, here's someone from a reputable university who says it really is orange: http://www.bk.psu.edu/faculty/cooper/solarsystem/mercury.html.
(Well, actually, it's his ten-year-old kid who made the webpage ...)

The general opinion seems to be that Mercury is like the Moon in colour and albedo. I kind of hoped that Fridger would eventually come up with a 1k version of his Mercury texture that he was happy to let out into the world, so I've been stalling around on this one for ages, but I don't think it's ever going to happen. :cry:
So it's really well past time to greyscale the existing texture, if nothing else.

Grant


Grant,

a 1k version of my Mercury texture just comes out horrible, as I have emphasized many times. I think it is due to the very high density of craters that get reduced to mere "fragments" upon rescaling so drastically.

I could do a quite acceptable 2k version, but 1k simply does not work. So that's the only reason I sort of gave up. Who wants to loose his reputation, just for doing the wrong thing...

But on the weekend, I'll do an anonymous 1k demo, nevertheless :roll:

Bye Fridger

_MackTuesday_

Post #7by _MackTuesday_ » 17.04.2004, 21:58

It's flourescent brown.


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