Talk:Sun

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Edit request- "faint young sun" section

Contrary to the above mentioned section in this article,(Sun#Faint_young_Sun_problem) there is actually NO consensus for the faint young sun paradox. The paper cited in this article is from 1986, since then a number of other papers have been published which categorically dispel the Greenhouse gas explanation.

Like this one published in Nature the journal in 2010 - Examination of Archaean sediments appears inconsistent with the hypothesis of high greenhouse concentrations. Instead, the moderate temperature range may be explained by a lower surface albedo brought about by less continental area and the "lack of biologically induced cloud condensation nuclei". This would have led to increased absorption of solar energy, thereby compensating for the lower solar output.

Moving Earth to hold in the bisophere

There is always only mentioned, that Earth bill be distryoed by the sun when changing to a red giant. Why not mention the possibility of changing Earth orbit? — Preceding unsigned comment added by Pege.founder (talk • contribs) 15:36, 29 January 2017 (UTC)

Because Wikipedia does not deal in speculation nor original research, except that which is commonly discussed in professionally published mainstream academic or journalistic sources. Besides, the time frame for the sun to expand is so far off that it raises the question whether or not humanity will even still be around, or whether the post-human race that evolves from us will even regard Earth as their home. Ian.thomson (talk) 23:24, 29 January 2017 (UTC)

An image for "Name and etimology"

It's a good article so i don't edit it directly, but I have found this image File:Multilanguages Sun.jpg if you think is appropriate you can insert it in the paragraph.--Alexmar983 (talk) 05:15, 11 February 2017 (UTC)

Planetary System

I added a little section about the planetary system of the Sun (i.e. the Solar System) because most articles about stars include a mention of their planetary system. As there is an in-depth article about the Solar System, I kept it short with a link to the main article. If anyone thinks that there should be more included in that section, feel free to stick it in. Titanium Dragon (talk) 03:30, 26 February 2017 (UTC)

Ammonia is not a greenhouse gas

Ammonia is not a greenhouse gas. Someone please change that. https://web.archive.org/web/20110726172415/https://www.iiar.org/aar/aar_green2.cfm — Preceding unsigned comment added by Qwed44 (talk • contribs) 18:08, 4 April 2017 (UTC)

 Done Thank you. Isambard Kingdom (talk) 18:27, 4 April 2017 (UTC)

Sunlight is not white. It's yellow.

Wikipedia has been infected by editors who are replacing a simple scientific fact with an experience based belief.

Fact: The sun is yellowish white. This is a scientific measurable fact: "the yellowish Sun has a B–V index of 0.656 ± 0.005" Scientists created a classification system for stars based on color & temperature with firmly yellowish stars being G class. In this classification system, white stars are classified from hottest F stars to coolest A stars. Scientists classified the sun as a G2V yellow dwarf.

Belief: The sun is white. 'cause it sure looks white to me. Couch pseudo-scientists use Google to find images and videos of the sun. They feel it's white. They have been editing Wikipedia pages to reflect this belief.

Their faulty logic: a) sunlight = black-body radiation b) black-body radiation has all wavelengths c) white = all wavelengths therefore sunlight is white

Their logic missed: d: the sun emits more light in the yellow region.

A simple dummy check, apply their logic to red giants: a) light from red giants = black-body radiation b) black-body radiation has all wavelengths c) white = all wavelengths therefore light from red giants is white

Clearly this argument is false.

Their supporting evidence: 1) Videos/photos from space show a white sun.

Problem with this supporting evidence: the sun looks white in videos/photos due to overexposure.

2) Sun looks white to astronauts. Any significantly bright black-body radiation will look white to us, the brightness maxes out our cones in our eyes. To see its color it has to be significantly dimmed.

3) Some source says the sun is white. Their source says the sun is white because of the same faulty reasons.

The facts.

"Most stars are currently classified under the Morgan–Keenan (MK) system using the letters O, B, A, F, G, K, and M, a sequence from the hottest (O type) to the coolest (M type). Each letter class is then subdivided using a numeric digit with 0 being hottest and 9 being coolest " https://en.wikipedia.org/wiki/Stellar_classification

O = "O-type stars are very hot and extremely luminous, with most of their radiated output in the ultraviolet range." these are BEYOND blue. B = ""B-type stars are very luminous and blue." A = "A-type stars ... are white or bluish-white." F = "temperature range gives the F-type stars a yellow-white hue." G = This is what is debated here. K = "K-type stars are orangish stars that are slightly cooler than the Sun." M = red dwarfs to brown dwarfs, colors ranging from orangish to magenta

To visualize better, main sequence stars from hottest to coolest: O0 - Ultraviolet blue O1 ... O9 - Very blue

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B0 - Very blue B1 ... B9 - blue

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A0 - bluish-white A1 ... A9 - white

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WHITE

F0 - white F1 ... F9 - yellow-white

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G0 - yellow white G1 G2 - - - - - - - -SUN ... G9 - yellow

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K - orangish M - reddish

Summary

The sun has been classified correctly as a G2V main sequence star because "the yellowish Sun has a B–V index of 0.656 ± 0.005" This page and other Wikipedia pages have to be fixed to reflect what science says.

And pages which say scientific facts such as the Earth is spheroidal and the Sun is yellow have to be protected from people whose gut feelings and Google searches led them to believe the Earth is flat and the Sun is white. — Preceding unsigned comment added by 89.70.184.249 (talk) 10:08, 16 April 2017 (UTC)

You are correct that the sun's light is on the yellowish side of white, in fact we mention that the most intense frequency is actually green, but the spectrum is much closer to white than to what most people would call yellow. Interpretation of colour is subjective, of course, so we need to specify the temperature, which we do. Dbfirs 10:50, 16 April 2017 (UTC)

Semi-protected edit request on 16 April 2017

Please change FROM "the Sun will become sufficiently large enough to engulf "

               TO "the Sun will become sufficiently large to engulf "

as the meaning "enough" is contained within "sufficiently" MisterArthurSludge (talk) 14:56, 16 April 2017 (UTC)

Done DRAGON BOOSTER ★ 15:03, 16 April 2017 (UTC)

Solar radius

There was radius 696342 km (last in revision oldid=709886995) as per https://arxiv.org/pdf/1203.4898 - the radius of the layer which is observed by MDI and HMI instruments on SOHO resp. SDO spacecrafts. With this value, there was correctly written: "the Sun's radius is considered to be the distance from its center to the edge of the photosphere, the apparent visible surface of the Sun" .

SDO spacecraft (HMI instrument) uses nominal Solar radius 6.96e8 m exactly.

At Revision oldid=710009490 as of 12:16, 14 March 2016 the value changed to 695700 km, as per IAU burreaucratic decision. In article Solar radius there is correctly stated: "The solar radius is usually defined as the radius to the layer in the Sun's photosphere where the optical depth equals 2/3 ." and also that it is a burreaucratic decision of IAU Resolution B3, and not a real measurement... (for a list of real measurements and their spread, let's see that arxiv 1203.4898 Fig.1 - published measurements of Solar radius)

Anyhow, at this article there stays the previous definition about "edge of the photosphere", which does not correspond with the value 6.957e8 m . It is necessary to correct definition of Radius down in text to read "where the optical depth equals 2/3", and possibly also to mention other values ("to the edge of photosphere 696342 km, to the photospheric layer as observed by MDI at wavelength 6173 A" etc...)

At the very least, shrinking the Sun by 642km should be better explained ! At least by adding "where the optical depth equals 2/3" in the definition of radius down in article text in "Characteristics" section...