Celestia Forums

This is my conception of what Gliese 581 c, the recently discovered Earth-like planet, may look like.

Here are some screenshots of the texture:

http://img.photobucket.com/albums/v243/bobdolesotherhat/Celestia/PLday.jpg
http://img.photobucket.com/albums/v243/bobdolesotherhat/Celestia/plnight.jpg

I'm also including an ssc file that will make this an alternate surface. You can download it here:

http://www.filesend.net/download.php?f=eefc86cc057a0abff3e2f38508a9686d

If you don't have the Gliese 581 c info in your extrasolar.ssc file, you can download the system here (this texture is included in the download):

http://www.filesend.net/download.php?f=a331cba6bbc8ee120a4c508f60f3e9d7

or you can get the most up-to-date extrasolar.ssc file, which includes Gliese 581 c, from here:

http://celestia.cvs.sourceforge.net/celestia/celestia/data/extrasolar.ssc

Thanks for posting your texture. I think that it will work better than the one I've been using. I wonder, should a texture for this planet show more surface water? At 2x Earth gravity, one would think that the vapor pressure for water would be less, and thus fewer clouds for the same temperature. Just idle musing - someone will likely correct me.

Nevertheless, you post good work. Now go and study for your finals!

Aphyle2007

I used my waterworld texture (Panthalassa, from the OA Complete add-on) to make this image;
http://img181.imageshack.us/img181/3752 ... 581jg4.jpg

John Dollan has a nice seaworld texture which could also yield good results.
The planet would be too hot for human habitation, whether it is a rocky world or a watery world;

but the thick atmosphere would probably allow the water to be in liquid form, so perhaps some kind of life might be possible.

Basically, everyone is clueless as to what the surface actually looks like, or even what the rotational properties, actual size, etc. are, so I just threw something together that matched one of the theories.

OK, I have just uploaded the Red Dwarf texture for Gliese 581 to Motherlode. It should appear in a few days under the category, "Extrasolar - Stars".

Note that I have not included any planets with the texture.

Also note that since the texture is a new spherical object enveloping Gliese 581, right-clicking on it will select it, not the parent star. As a result, you will not see a list of "satellites" associated with the object if you right-click on it.

To see the planets around Gliese 581, either zoom out so you can see them and click on them to select them, or use the Navigation/Solar System Browser menu in Celestia. All the planets will be listed and easily selectable.

Enjoy

Frank

In my view this red dwarf texture does not look like a really "glowing"/emissive object. Rather like a dark red painted ball...

I had a look at NASA's recent spectacular 3d images of our sun from the STEREO project.

http://photojournal.jpl.nasa.gov/target/Sun?start=10

This is filtered such as to emulate much better something that might look like Gliese 581:



Here is Franks "red ball" for comparison...



Bye Fridger

I agree with Fridger here. The red "painted ball" texture looks like some brown dwarf to me, not like a red star. O well, ...

Yep, its true! The Red Dwarf I uploaded seems dull compared to NASA's brilliant ball. However, I'm not so sure it is that dull.

here are two artist images of what a Red Dwarf might look like. The first is an artist's rendition of Gliese 581 with its newly discovered planet.
The 2nd is a painting of a generic red dwarf. In both cases, the glow is muted. Both images are from NASA.






Compared to the image I uploaded, there is some difference in brightness, but not that much actually. The main difference is in the atmosphere. There is not much flare apparent. However, if it is too dull, is there any way to boost the glow of an ssc texture? I am already using emissive true! I suppose I could lighten the texture but it still will not glow as well as the NASA image. Any suggeestions??

Frank

Frank,

Have you tried a semi-transparent texture for your add-on? I don't know if that would work but there are fully tranparent sphere models that can be skinned with tranparent textures. Runar's Sol add-on has tranparent Spheroids with the flare textures on them and they rotate through the sun simulating flares. So if you use this model, ajusts its parameters to make it round instead and placed it around said star and placed a semi-transparent texture over it you could posibly get what you are looking for. Light from Celestia's rendered Red Dwarf setting and texture with a color mask over it.
I could put it together if I had your add-on and texture and then I could post a few pics with the results. In therory it should work. Let me know either here or PM me.

Don. Edwards

I just a quick and dirty try at this and this is what I came up with. I have the mesh and texture wraped around a G type star but it would look better around a real type M.



I think this gives it a little more of what you may trying to achieve.

Don. Edwards

fsgregs wrote:Yep, its true! The Red Dwarf I uploaded seems dull compared to NASA's brilliant ball. However, I'm not so sure it is that dull.

here are two artist images of what a Red Dwarf might look like. The first is an artist's rendition of Gliese 581 with its newly discovered planet.
The 2nd is a painting of a generic red dwarf. In both cases, the glow is muted. Both images are from NASA.






Compared to the image I uploaded, there is some difference in brightness, but not that much actually. The main difference is in the atmosphere. There is not much flare apparent. However, if it is too dull, is there any way to boost the glow of an ssc texture? I am already using emissive true! I suppose I could lighten the texture but it still will not glow as well as the NASA image. Any suggeestions??

Frank

Frank,

you know how critical I often am as concerns so-called "space artist" images, even though they might appear on NASA sites...Many of those "artists" are certainly not professional astrophysicists as one can tell from their images...

The first of the two images you cite from the NASA site is even physically wrong: how come that the light from Gliese 581 that illuminates the shown planet is WHITE, while the star is DEEP RED??
Please explain...

The second image is way better. I guess like my image above the "artist" used one of the red SOHO sun photographs as a base....

http://sohowww.nascom.nasa.gov/data/rea ... t_195/512/

Making this a little redder is a matter of minutes...

In any case that second image is kind of "alive" while your red ball is "dead". sorry...Just fine for ML


Bye Fridger

Bear in mind also that Gliese 581 is a BY Draconis type variable.

From what I've been able to find out about such stars, it suggests that large portions of the surface may be covered in starspots.

I'm also unconvinced about the possibility of liquid water on Gliese 581 c, for the following reason:

Luminosity of Gliese 581 = 0.013*solar
Semimajor axis of Gliese 581 c = 0.073 AU

0.013/0.073^2 = 2.44 times the amount of power received per square metre at Gliese 581 c's orbit than at Earth.

For comparison, semimajor axis of Venus (not famous for its habitable climate) = 0.723 AU

1/0.723^2 = 1.91 (a number that is clearly less than 2.44) times the amount of power received per square metre at Venus than at Earth.

Draw your own conclusions.

but in celestia the luminosity is 0.00201 of sun...
then: 0,37 times the sun...
what's wrong???

post scriptum...
but from wiipedia link: http://en.wikipedia.org/wiki/Gliese_581_c

Temperature and habitability

Scale comparison of the relative sizes of the Earth and Gliese 581 c, assuming Gliese 581 c is a rocky body

Temperature

Using the measured stellar luminosity of Gliese 581 of 0.013 times that of our Sun, it is possible to calculate Gliese 581 c equilibrium surface temperature, although without taking into consideration effects on the mean temperature by a possible atmosphere through natural global warming. According to Udry's team the equilibrium temperature for Gliese 581 c is -3?°C / 26.6?° F assuming an albedo (how much light is reflected by the planet's surface) such as Venus (0.64) and 40?°C / 104?° F for an Earth-like albedo (0.35). [6][2] However, the actual temperature on the surface depends, beside the actual value of the planet's albedo, on the planet's atmosphere, which also remains unknown. Xavier Delfosse of the research team expects that the actual surface temperatures will be hotter; for instance, the corresponding calculation for Earth yields an "effective surface temperature" of 256 K (??’17 ?°C), yet Earth's true surface is 32 K warmer, an average of 288 K (15 ?°C), due to the greenhouse effect of its atmosphere.[13]

Liquid water

Gliese 581 c is within the habitable zone where liquid water ?€“ a necessary ingredient for life as we know it ?€“ could exist.[3][14]

Although the potential for liquid water is predicted by the habitable-zone model, no direct evidence has been found. Techniques like the one used to measure HD 209458 b could be applied to determine the existence of water vapor in an extrasolar planet's atmosphere, but this method requires the rare coincidence of a planet whose orbit causes it to transit directly between its star and our planet; this is something Gliese 581 c is not known to do.

Tidal forces

Because of its close orbit, the planet would experience tides from its parent star about 400 times as strong as those that the Moon causes on the Earth. It may be tidally locked to the star, with one hemisphere always lit and the other always dark.[15] The lit hemisphere might be extremely hot and the dark hemisphere extremely cold, while the narrow terminator or "twilight zone" between them might have a moderate climate more suitable for life similar to Earth's.[16]

A theoretical model predicts that volatile compounds such as water and carbon dioxide might evaporate in the scorching heat of the sunward side, migrate to the cooler night side, and condense to form ice caps. Over time, the entire atmosphere could become frozen as ice caps on the night side of the planet. Alternatively, if it has an atmosphere large enough to be stable, it should circulate the heat more evenly, allowing for a wider habitable area on the surface.[17]

brunetto_64: Celestia is displaying the visual luminosity - that is, how much visible light the star puts out compared to the amount of visible light put out by the Sun. This is because the magnitude data supplied to Celestia are for the visible part of the spectrum. Since red dwarfs radiate mainly in the infrared, this underestimates the total luminosity.

I took the value of 0.013 from the discovery paper of the planet, available here.

This entire "habitable planet" issue is based on effective temperature of the planet, which is not very sensible. In fact, you can do the analysis on Venus and Earth, assuming we only know how luminous the Sun is, the distances of the planets from the sun, and that the albedo could range between that of Earth and Venus. You end up with the following temperature ranges:

Venus: -20 degrees C to +20 degrees C
Earth: -50 degrees C to -20 degrees C

Yet Gliese 581 is reported to be between 0 and 40 degrees C... a warmer temperature range than the one we would calculate for Venus! I guess in the eyes of the science journalists, Venus is a planet barely warm enough to be habitable, and Earth is a frozen iceball.

I prefer not to get my information from Wikipedia myself - there is higher regard for information presented in the media than there is for a basic physics analysis (which counts as "original research")... this is the nature of truth by mob consensus.

chaos syndrome wrote:...
I prefer not to get my information from Wikipedia myself - there is higher regard for information presented in the media than there is for a basic physics analysis (which counts as "original research")... this is the nature of truth by mob consensus.

What a pleasure to read!

I "love" science journalism...(exceptions admitted, of course!)

Somehow throughout my professional life, I have been too much in contact with superficial/incompetent "science journalists", "space artists" and the like...


If people without the required scientific background start copying together half-digested information from other WEB sites where the content was obtained in a similar fashion...I tend to develop a spontaneous "stomach problem"

Bye Fridger

bobdolesrevenge1 wrote:This is my conception of what Gliese 581 c, the recently discovered Earth-like planet, may look like.

Here are some screenshots of the texture:

http://www.imageuploads.net/ims/pic.php?u=18219BHv9m&i=123316
http://www.imageuploads.net/ims/pic.php?u=18219BHv9m&i=123317

I'm also including an ssc file that will make this an alternate surface. You can download it here:

http://www.filesend.net/download.php?f=eefc86cc057a0abff3e2f38508a9686d

If you don't have the Gliese 581 c info in your extrasolar.ssc file, you can download the system here (this texture is included in the download):

http://www.filesend.net/download.php?f=a331cba6bbc8ee120a4c508f60f3e9d7

or you can get the most up-to-date extrasolar.ssc file, which includes Gliese 581 c, from here:

http://celestia.cvs.sourceforge.net/celestia/celestia/data/extrasolar.ssc

It says 'image not available"

It says 'image not available"

Sorry about that. There was a problem with the website I uploaded my pictures to. I corrected the links on my first entry, they should work now.

Don. Edwards, do you have a download link for your red dwarf texture available?

Hows this for What Gliese 581 might look like.




Don. Edwards

All these images seem too dull (in colour, I don't mean they're boring!) If I was in the Gliese 581 system and looking at the star, would I really be able to stare at it like I would a glowing ember? Or would it be blindingly bright and hurt my eyes, even if less so than our Sun? If so, shouldn't it be rendered a pale pink colour rather than these crimson versions?

The Singing Badger wrote:All these images seem too dull (in colour, I don't mean they're boring!) If I was in the Gliese 581 system and looking at the star, would I really be able to stare at it like I would a glowing ember? Or would it be blindingly bright and hurt my eyes, even if less so than our Sun? If so, shouldn't it be rendered a pale pink colour rather than these crimson versions?

It's my understanding that, to the Human eye, even a red dwarf would be blindingly bright to the naked eye, and would shine fairly white, like our sun does. I'm sure others can give more detailed explanations, though.

...John...