Pictures from Celestia

General discussion about Celestia that doesn't fit into other forums.
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SevenSpheres
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Post #661by SevenSpheres » 07.06.2021, 20:40

Eric Nelson wrote:Well remember since it's part of a circumbinary star system containing 1 F8 main sequence star (which's white) and 1 red dwarf star, the white and red combo lead to a pink reflection.

That's not really how it works, look up "blackbody spectrum". That being said, there's certainly nothing wrong with texturing the planet based on the artist's impression.

Eric Nelson wrote:I haven't found any sources for the positions of the stars in their orbits, but I did make a file of the 2 stars whose positions are based on their epochs (matching the discovery date).

Too bad Celestia Origin has TOI-1338 as a single G-star and the planet as unconfirmed with a radius that's overexaggerated compared to its true radius.

If you look at the pinned threads on the "Add-on releases" subforum, you'll see this exoplanet catalog, which is updated every month. Celestia Origin's exoplanet database is based on an older version of the catalog, which is why it has some outdated data.

Anyway, to bring this thread back on topic, here's an ocean planet with clouds from MrSpace43's generator.

himinglaeva2.png
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Post #662by Eric Nelson » 07.06.2021, 22:48

Celestia Origin needs some massive updating on some files, like exoplanets and stars.

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Sirius_Alpha
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Post #663by Sirius_Alpha » 08.06.2021, 01:52

<shameless plug>
You can always download the latest catalogue of extrasolar planets here.
Exoplanet nerd. I maintain a monthly-updated exoplanet catalogue here:
https://celestia.space/forum/viewtopic.php?f=23&t=18705

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trappistplanets
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Post #664by trappistplanets » 08.06.2021, 11:30

Eric Nelson wrote:Celestia Origin needs some massive updating on some files, like exoplanets and stars.
true, they should be keeping up to date with tom's catalog

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Post #665by Eric Nelson » 08.06.2021, 11:51

trappistplanets wrote:true, they should be keeping up to date with tom's catalog
Yup. That's among the things on CO that should be kept up to date the most often.

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trappistplanets
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Post #666by trappistplanets » 08.06.2021, 12:48

Eric Nelson wrote:Yup. That's among the things on CO that should be kept up to date the most often.
very very true

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Post #667by Eric Nelson » 08.06.2021, 17:07

Yup and I even had to change the radius of HD 100546 b on Art Blos' Celestia Origin to its most accepted value, add a night texture (sudarsky-class_4-night.dds) a red color to it and change the Mie colors to match the most accepted appearance.
It's ~20X Jupiter's mass (which matches that of a typical brown dwarf hence the reddish appearance) and ~6.9 x Jupiter's radius (which in turn's 71492 km total, so multiply that by 6.9X though exoplanets there round such radii despite the math).
Plus, with a rotation tidally locked with its orbit which's a staggering 249.039582 Earth years, an oblateness of such should be too negligible to be detected by any means, so set it to 0.0.

"b:HD 100546 b" "HD 100546"
{
Class "planet"
Texture "sudarsky-class_1.dds"
NightTexture "sudarsky-class_4-night.dds"
Radius 493295
Color [ 1.0 0 0 ]
BlendTexture true
Oblateness 0.0
Atmosphere
{
Height 1000
Mie 0.001
MieScaleHeight 27
MieAsymmetry -0.15
Rayleigh [ 0.0007 0.0003 0.0002 ]
Absorption [ 0.0005 0.0007 0.0010 ]
}
EllipticalOrbit
{
Period 249.039582
SemiMajorAxis 53
ArgOfPericenter 35.171
}
LunarLambert 0.5
}

The atmospheric scale height remains unchanged and gives a sense of scale for such a nonstellar body orbiting a main sequence star.
This's the most widely viewed impression of how HD 100546 b might look up close.

Added after 39 minutes 30 seconds:
Yet that wasn't the only body on the exoplanet file that needed fixing besides TOI-1338b, but TRES-2 Ab also needed fixing since it's the darkest planet known to orbit a star and has an albedo of 0.0136 (1.36%) in bond though the best-fit model gives it an albedo as low as 0.0004 (0.04%) indicating 1 albedo value 0.0136 means 98.64% of light's absorbed whereas an albedo of 0.0004% means 99.96% of that light from its host star's absorbed despite orbiting so close to its star (TRES-2 A).
With such values, the dayside's darker than that of other planets.
The night texture had to be hashed out for such reason.
And the atmosphere had to be reduced to 1/1000 of its luminosity (for the 0.0004 albedo value).
https://web.archive.org/web/20120317203801/http://www.astro.princeton.edu/~dsp/PrincetonSite/Home_files/darkest_world.pdf

"b:KOI-1.01:Kepler-1 Ab:TrES-2 Ab" "TrES-2 A"
{
Class "planet"
Texture "sudarsky-class_4.dds"
#NightTexture "sudarsky-class_4-night.dds"
Color [ 0 0.00036 0.001 ]
BlendTexture true
Radius 81726
Oblateness 0.065
Atmosphere
{
Height 5000
Lower [ 0.0002 0.0003 0.0004 ]
Upper [ 0.0001 0.0002 0.0002 ]
Sky [ 0.0003 0.0004 0.0005 ]
Sunset [ 0.0004 0.0002 0.0001 ]
}
EllipticalOrbit
{
Epoch 2453957.635486
Period 0.006764
SemiMajorAxis 0.03556
Inclination 92.297
AscendingNode 291.992
ArgOfPericenter 161.108
MeanAnomaly 90
}
UniformRotation
{
Inclination 92.297
AscendingNode 291.992
}
LunarLambert 0.5
Albedo 0.0004
InfoURL "http://arxiv.org/abs/astro-ph/0609335"
}
Attachments
TRES-2 b.png
TRES-2 Ab absorbs ~99.96% of all visible light from its host star, giving it an albedo of 0.0004 (0.04%)
hd 100546.png
HD 100546 b dayside
hd 100546 b night.png
HD 100546 b nightside
Last edited by Eric Nelson on 08.06.2021, 23:38, edited 4 times in total.

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Anthony_B_Russo10
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Post #668by Anthony_B_Russo10 » 08.06.2021, 22:00

The main thing is that there are multiple months between CO updates, the Exoplanet Catalog gets updated every months.
Anthony B. Russo, I like Pluto. Mod of the Celestia subreddit: https://www.reddit.com/r/Celestiasoftware/
I have over 30 computers, trying to list them here would be a pain.

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Post #669by Eric Nelson » 08.06.2021, 22:25

Yup and it's worth the patience and effort to get it all up to date.

Added after 1 hour 42 minutes:
Here's TRES-2 Ab with the albedo at 0.0136 (1.36%) which's what it's also often recognized at being and many sources also state it's albedo's 0.0136.

Somehow many state it's 0.0136 and others state it's 0.0004 (0.04%) which's incredibly low.

"b:KOI-1.01:Kepler-1 Ab:TrES-2 Ab" "TrES-2 A"
{
Class "planet"
Texture "sudarsky-class_4.dds"
#NightTexture "sudarsky-class_4-night.dds"
Color [ 0 0.036 0.1 ]
BlendTexture true
Radius 81726
Oblateness 0.065
Atmosphere
{
Height 5000
Lower [ 0.02 0.03 0.04 ]
Upper [ 0.01 0.02 0.02 ]
Sky [ 0.03 0.04 0.05 ]
Sunset [ 0.04 0.02 0.01 ]
}
EllipticalOrbit
{
Epoch 2453957.635486
Period 0.006764
SemiMajorAxis 0.03556
Inclination 92.297
AscendingNode 291.992
ArgOfPericenter 161.108
MeanAnomaly 90
}
UniformRotation
{
Inclination 92.297
AscendingNode 291.992
}
LunarLambert 0.5
Albedo 0.0136
InfoURL "http://arxiv.org/abs/astro-ph/0609335"
}

As you can see, daylight's still visible and you can even make out what the atmospheric luminosity looks like at daylight there.

It's still dark in this but not nearly as close to pitch black as the media states.
Attachments
tres-2b.png
Tres-2 Ab with an albedo of 0.0136% meaning only 98.64% of all its incoming white starlight's absorbed.

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fyr02
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Post #670by fyr02 » 09.06.2021, 02:58

I should mention that the brightness of TrES-2 b is heavily exaggerated here.
Albedo is not linear to brightness - because the way the eye perceives light is not linear, TrES-2 b would appear (adjusting for distance to star) a comfortable dark gray - nowhere near the black in the picture.
Image

Eric Nelson
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Post #671by Eric Nelson » 09.06.2021, 09:50

Well the media needs to stop stretching the truth about so many things.
Even though they say planets like this TRES-2 Ab for example reflect very little light, hence they declare them "pitch-black".
Last edited by Eric Nelson on 09.06.2021, 11:32, edited 1 time in total.

john71
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Post #672by john71 » 09.06.2021, 10:52

Mars with new 64k normal map:

Mars 2021 06 - 1.png
Mars 2021 06 - 4.png
Mars 2021 06 - 5.png
Mars 2021 06 - 6.png

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Post #673by Eric Nelson » 09.06.2021, 11:33

That's 1 update CO needs at some point in time.
Mars looks very crisp in these photos, almost like you're there except it's all an illusion from lighting.

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Post #674by john71 » 09.06.2021, 16:29

Eric Nelson wrote:almost like you're there except it's all an illusion from lighting.

At this resolution (256k texture) using a "flat" sphere is clearly not enough.

These are mountains projected on a sphere and no amount of light effects can hide that.

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Post #675by Eric Nelson » 09.06.2021, 17:46

Yup and Mars has some mountains despite not being as geologically active in the same way Earth is.

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Post #676by trappistplanets » 09.06.2021, 18:08

john71 wrote:These are mountains projected on a sphere and no amount of light effects can hide that.
very very true


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