Talk:Sun

Unsafe conclusion in Motion and location

Under the subtitle "Motion in the Solar System"

There is an unsupported conclusion with an orphan reference. To wit: "[…] The orbits of the inner planets, including of the Earth, are similarly displaced by the same gravitational forces, so the movement of the Sun has little effect on the relative positions of the Earth and the Sun or on solar irradiance on the Earth as a function of time.[140] […]"

Checking footnote 140 reveals:

Retraction of: Scientific Reports 10.1038/s41598-019-45584-3, published online 24 June 2019 The Editors have retracted this Article. After publication, concerns were raised regarding the interpretation of how the Earth-Sun distance changes over time and that some of the assumptions on which analyses presented in the Article are based are incorrect.The analyses presented in the section entitled “Effects of SIM on a temperature in the terrestrial hemispheres” are based on the assumption that the orbits of the Earth and the Sun about the Solar System barycenter are uncorrelated, so that the Earth-Sun distance changes by an amount comparable to the Sun-barycenter distance. Post-publication peer review has shown that this assumption is inaccurate because the motions of the Earth and the Sun are primarily due to Jupiter and the other giant planets, which accelerate the Earth and the Sun in nearly the same direction, and thereby generate highly-correlated motions in the Earth and Sun. Current ephemeris calculations [1,2] show that the Earth-Sun distance varies over a timescale of a few centuries by substantially less than the amount reported in this article. As a result the Editors no longer have confidence in the conclusions presented. S. I. Zharkov agrees with the retraction. V. V. Zharkova, E. Popova, and S. J. Shepherd disagree with the retraction.

[1] Folkner, W. M., Williams, J. G., Boggs, D. H., Park, R.S. & Kuchynka, P. The Planetary and Lunar Ephemerides DE430 and DE431. "The Interplanetary Network Progress Report", Volume 42–196, February 15, 2014.

[2] JPL Horizons on-line solar system data. Horizons System

Reference: Retraction Note: Oscillations of the baseline of solar magnetic field and solar irradiance on a millennial timescale

Equatorial Radius

Isn't it kind of misleading to put meters as the equatorial radius unit because you would expect the unit to be kilometers instead. PeanutbutterCat6Meow (talk) 14:54, 7 August 2024 (UTC)

Also I noticed that the surface area is in square kilometers instead of square meters which you would expect if radius is in meters. PeanutbutterCat6Meow (talk) 15:26, 7 August 2024 (UTC)

I don't know which unit one should "expect". With the metric system, in any case, conversion is trivial (10^8 m = 10^5 km; 10^12 km^2 = 10^18 m^2). For what it is worth, the units are the same as in the given sources, which have (resp.) the radius in meters and the surface area in kilometers. 69.165.195.198 (talk) 22:47, 9 August 2024 (UTC)

"The Sun" or "Sun"?

Why do we call "The Sun" and not just simply called "Sun", like other stars names (Spica, Arcturus, Vega, etc) that don't have "The" word accompanying them? 2001:1388:1B8E:BBB1:9CBC:C8B4:1DCC:4732 (talk) 18:17, 11 August 2024 (UTC)

Once outside the Sun's surface, neutrinos and photons travel at the speed of light.

To me this figure label makes no sense. Neutrinos are believed to have a mass, so if special relativity is right, they cannot travel at speed of light. On the other hand photons should always travel at speed of light, regardless if the photon is in the sun or outside. The speed of light and especially time progression in the sun might be different from the normal value on earth and the mean free path is short, but photons should still travel with speed of light. 80.135.118.117 (talk) 16:23, 19 September 2024 (UTC)

For what it's worth, this is referring to the diagram in the "Sunlight and neutrinos" section. The diagram isn't particularly interesting, is imprecise, and the caption is obscure. The fourth paragraph of that section explains what the caption refers to, but is a factoid largely irrelevant outside supernova explosion studies. Tarl N. (discuss) 22:41, 19 September 2024 (UTC)

Source of Energy

In the introduction, without citation, there is a claim that The Sun is by far the most important source of energy for planet Earth. What does this mean? It does not relate to kilocalories or kilojoules or calories, clearly. Does it provide the greatest amount of solar power, literally, to animals and machines that store or use it? Or is it that the total volume of photosynthesis energy for plants exceeds animal and plant calorie consumption? Or do solar effects create weather systems, waves etc with overriding kinetic energy? Etc etc. An explanation of 'energy' or a citation is required. Or else this is genuinely vague beyond comprehension. Texluh1138 (talk) 23:41, 2 October 2024 (UTC)

@Texluh1138 In general, per MOS:LEAD the intro paragraphs don't need citations if the article supports the content with verifiable refs and the topic is not controversial. The actual sentence is:

• It is by far the most important source of energy for life on Earth.

which in my opinion cannot be controversial. Note "life on Earth".

This is supported by the ref in the "General characteristics" section.

• The energy of this sunlight supports almost all life on Earth by photosynthesis,("The Sun's Energy: An Essential Part of the Earth System". Center for Science Education. Retrieved 24 May 2024.) and drives Earth's climate and weather.("The Sun's Influence on Climate". Princeton University Press. 23 June 2015. Retrieved 24 May 2024.)

Johnjbarton (talk) 23:51, 2 October 2024 (UTC)

Agreed that it's in the general characteristics sections and I'd overlooked that, and I'm happy to withdraw the comment. Texluh1138 (talk) 12:54, 3 October 2024 (UTC)

References

faint young Sun paradox

@Praemonitus removed the summary of Faint young Sun paradox, but in my opinion this topic is a great application of our understand (or lack) of the Sun's life history and should be included in this article. Johnjbarton (talk) 15:52, 11 October 2024 (UTC)

I do see the point that it is related to the Sun's life history. OTOH, the predominant theory according to Faint young Sun paradox has a lot more to do with the Earth (greenhouse effect) than it does with the Sun, so maybe it's not actually that revealing a data point regarding the Sun's evolution. Double sharp (talk) 16:30, 11 October 2024 (UTC)

Ok thanks, I think that is what Praemonitus was getting at. Johnjbarton (talk) 16:40, 11 October 2024 (UTC)

Yes, the point about the increases to the Sun's luminosity and radius are already covered in the "Main sequence" section, so I didn't see a need to repeat that. There is a chart on the Solar luminosity article that provides useful information on the topic. Praemonitus (talk) 19:10, 11 October 2024 (UTC)

Question about the chemical abundances of the Sun

The Composition section says the following:

• At this time in the Sun's life, they account for 74.9% and 23.8%, respectively, of the mass of the Sun in the photosphere.
• Originally it would have been about 71.1% hydrogen, 27.4% helium, and 1.5% heavier elements.

I'm puzzled about why the Sun would lose helium mass at the photosphere. Was it a diffusion process? (Cf. chemically peculiar star.) The article needs to explain it. Praemonitus (talk) 15:08, 14 October 2024 (UTC)

Not a loss of helium but a gain of heavier elements. See Introduction:

• Lodders, K. (2021). Relative atomic solar system abundances, mass fractions, and atomic masses of the elements and their isotopes, composition of the solar photosphere, and compositions of the major chondritic meteorite groups. Space Science Reviews, 217(3), 44.

Johnjbarton (talk) 16:36, 14 October 2024 (UTC)

The H + He account for 98.5% at the start and 98.7% at present. Hence, the heavier elements have decreased in mass. Hmm. Praemonitus (talk) 18:17, 14 October 2024 (UTC)

Okay, it's covered by the next paragraph: heavy element settling from the photosphere. Praemonitus (talk) 20:33, 15 October 2024 (UTC)

Norman or Joseph?

The article refers to "Norman" Lockyer and later to "Joseph" Lockyer even though the same person is indicated.

Some consistent name should be chosen and used consistently. 71.128.242.202 (talk) 19:37, 25 October 2024 (UTC)

I did not find any mention of "Joseph Lockyer". The person named "Joseph Norman Lockyer" went exclusively by "Norman Lockyer". See Talk:Norman Lockyer. Johnjbarton (talk) 00:18, 26 October 2024 (UTC)

I simplified the mention of 'Joseph Lockyer' earlier to just 'Lockyer' since Norman Lockyer was mentioned just a couple sentences above. Sgubaldo (talk) 00:21, 26 October 2024 (UTC)

Ok great, I saw that. So fixed!  Done Johnjbarton (talk) 00:25, 26 October 2024 (UTC)