嗯! 沒錯~ 有時題目看似簡單, 背後意義卻蠻深遠的~

另外您所引用中文 wiki 內容似乎有點問題, 因為相同章節英文版並沒有提到千萬年, 而是提到依據現行模型, 光子從核心區域旅行到表面約要 17 萬年:

Energy transfer

According to current models, random scattering from free electrons in the solar radiative zone (the zone within 75% of the solar radius, where heat transfer is by radiation) sets the photon diffusion time scale (or "photon travel time") from the core to the outer edge of the radiative zone at about 170,000 years.

而我前面提到一萬年到17萬年的依據在此:

Photons and neutrinos

High-energy gamma-ray photons initially released with fusion reactions in the core are almost immediately absorbed by the solar plasma of the radiative zone, usually after traveling only a few millimeters. Re-emission happens in a random direction and usually at a slightly lower energy. With this sequence of emissions and absorptions, it takes a long time for radiation to reach the Sun's surface. Estimates of the photon travel time range between 10,000 and 170,000 years

依您所提中文版, 千萬年的依據是:

Lewis, Richard. The Illustrated Encyclopedia of the Universe. Harmony Books, New York. 1983: 65.

我沒找它內容, 原本猜測可能是較早期的模型, 不過我所引用內容接下來有一段敘述:

Because energy transport in the Sun is a process that involves photons in thermodynamic equilibrium with matter, the time scale of energy transport in the Sun is longer, on the order of 30,000,000 years. This is the time it would take the Sun to return to a stable state, if the rate of energy generation in its core were suddenly changed.[90]

引用依據裡的摘要:

On the time scale of energy transport in the sun

Abstract

It is pointed out that the time scale of energy transport in the Sun is the Kelvin–Helmholtz time scale, of order 3×10^7 years, roughly 100 times longer than the photon-diffusion time estimated by Mitalas and Sills (1992). The difference corresponds to a factor U gas/U rad, the ratio of thermal energy density to radiation energy density. Thus the heat transport, even when mediated by photons, is slowed down by the large heat capacity of the star. A numerical example calculation is presented.

所以千萬年的說法, 應不是指光子..

所以若單論光子, 依目前典型模型, 從源頭到表面應該是約一萬年到十七萬年左右; 當然啦, 將來說不定會有 (or 採用) 其它模型, 而有其它差異很大的數值出現..