Commons:Featured picture candidates/File:Star-sizes.jpg

File:Star-sizes.jpg, featured

Voting period ends on 14 Jul 2009 at 20:32:32

•  Info created by Thangalin - uploaded by Thangalin - nominated by Thangalin -- Thangalin (talk) 20:32, 5 July 2009 (UTC)
•  Support -- Thangalin (talk) 20:32, 5 July 2009 (UTC)
•  Support --Aqwis (talk) 21:13, 5 July 2009 (UTC)
•  Support --Alchemist-hp (talk) 21:34, 5 July 2009 (UTC)
•  Question What are the colors of the stars based on? bamse (talk) 23:08, 5 July 2009 (UTC)
•  Comment Updated star colours using Wien's Law to calculate the perceived wavelengths, based on the most recent estimates that I could find for the star's surface temperature. Temperatures and sources are noted on the image details page. Thangalin (talk) 01:38, 6 July 2009 (UTC)

Thanks. The texture/material is based on what? Some stars range in color from yellow to red. Please correct me, but I don't think the temperature/wavelength is known to astronomers on this scale. Besides it would likely change over time. bamse (talk) 07:45, 6 July 2009 (UTC)

•  Comment bamse: See the Hertzsprung-Russel Diagram for details. Temperature can be determined. See the Antares page for details. Planet texture maps are mostly from Celestia Motherlode and in the public domain (Earth was from a different site, but also PD). The textures for the stars are simulated, mostly based on textures from our Sun. Yes, the colours will change over time. I will update the image 10,000 years from now (if I remember). ;-) Thangalin (talk) 08:05, 6 July 2009 (UTC)

Yes, I remember the Hertzsprung-Russel Diagram from my high school, but that was not my question. Sorry for being so persistent. I have no doubt about the planet textures, since the details can be observed through telescopes or via space crafts. My problem is with the stars which are much further away. You say that you simulated their textures based on the texture from our sun. Can you tell a little more about the simulation part? Also, if I wanted to determine the temperature of "VV Cephei A", should I look at the yellow or the red parts of it? bamse (talk) 09:02, 6 July 2009 (UTC)

I downloaded a few pictures from SOHO and created texture maps from them. The texture maps were applied at various opacities against the base colour of the sphere (derived through Wien's Law). To determine the temperature of VV Cephei A, look at its average colour, rather than its variances. Thangalin (talk) 05:36, 7 July 2009 (UTC)

Thanks for clarifying. Do I understand correctly that the textures of the stars (except the one of our sun) are chosen for beauty rather than based on scientific grounds? If that is the case I would be glad if you added a note in the image description. In any case the description should state that the average color represents the temperature (through Wien's law). bamse (talk) 08:29, 7 July 2009 (UTC)

You're welcome. Since we have no textures of distant stars, all the star textures are based on the Sun, for aesthetic purposes. It would be misleading to state the average colour represents the temperature for a few reasons. (1) Star temperatures are determined within a range. (2) Wien's Law works best with large stars, such as red giants. (3) The colours are likely close, but are not exact matches due to texture map opacity levels and procedural shaders. It would be simplest to state that star colours are estimated (and Saturn's rings are slightly larger in the picture than to scale). Thangalin (talk) 23:40, 7 July 2009 (UTC)

•  Support looks OK to me (but I'm no expert) --ianaré (talk) 23:13, 5 July 2009 (UTC)
•  Support Wow. But I thought the biggest stars were blue? →Diti the penguin — 23:36, 5 July 2009 (UTC)
•  Comment The colour of a star depends on its size and temperature.
  • Yes, and the bigger the star, the bluer it is, isn't it? →Diti the penguin — 11:26, 7 July 2009 (UTC)
•  Comment same stars seems to appear in absolute different colours, isn't it? --Mbdortmund (talk) 01:02, 6 July 2009 (UTC)
•  Comment The same star will vary in colour from one picture to the next due to slight differences in lighting. (The spheres and materials, however, were imported directly from one scene into the next. The spheres were resized, but colour settings never changed.) Thangalin (talk) 01:38, 6 July 2009 (UTC)
•  Comment This image was reviewed for technical accuracy by Stephen Shawl for inclusion in a K12 astronomy textbook. Thangalin (talk) 01:54, 6 July 2009 (UTC)
•  Support Now I'm a believer... --Mbdortmund (talk) 11:38, 6 July 2009 (UTC)
•  Support--Mbz1 (talk) 03:01, 6 July 2009 (UTC)
•  Support Wow, amazing representation of celestial bodies. Acablue (talk) 06:12, 6 July 2009 (UTC)
•  Support Good and very interesting. Yann (talk) 09:47, 6 July 2009 (UTC)
•  Support very good --George Chernilevsky (talk) 10:12, 6 July 2009 (UTC)
•  Support —kallerna™ 11:19, 6 July 2009 (UTC)
•  Support Excellent quality and great encyclopedic value. Congratulations! -- MJJR (talk) 21:29, 6 July 2009 (UTC)
•  Support Very well done. Intuitive, informative, interesting, impressive... Ikluft (talk) 23:47, 6 July 2009 (UTC)
•  Comment it would have been nice if we could access the original 3d format. How did u create this anyhow? Great image.--Diaa abdelmoneim (talk) 11:43, 8 July 2009 (UTC)

Blender 3D was used for the models, lighting, and rendering. The GIMP was used to assemble and label the six renders into a single image. Saturn's rings were difficult to get right (which is why the previous versions lacked them). I used Wolfram Alpha to calculate each sphere's base colour. Then simply calculate the relative sizes of spheres in terms of their representative solar radius (in other words: divide some numbers). Thangalin (talk) 01:46, 9 July 2009 (UTC)

Could u add this info to the description of the file? With links to where you got the textures or possibly adding the textures themselves to commons and linking to them? BTW. The shadows pose a problem in the image as they go somtimes to the right, left and center depending on their place. For consistency I'd propose using sky light so the shadows wouldn't be that sharp. The crop on the image 3 is also very tight. It would be best if this was widened.--Diaa abdelmoneim (talk) 13:53, 12 July 2009 (UTC)

The shadows are consistent: the spotlight is always over the second-to-last sphere (to emphasize Saturn's transparent rings). Consequently, all shadows to the left of the second-to-last sphere point left and all shadows for the last sphere point right. Softening the shadows will blur the ring shadows, making it harder to discern the pattern of light passing through (take a close look at Uranus for the fine shading details). The crop on images 3 and 5 are too tight and will be resolved. (Betelgeuse should be further right for more space near its name.) Thangalin (talk) 00:39, 13 July 2009 (UTC)

result: 13 support, 0 oppose, 0 neutral => featured. Maedin\talk 11:55, 15 July 2009 (UTC)