i have found [a new interpretation][1] of [quran 18:86-90][2] :

"Sahih International" translation :

> Until, when he reached the setting of the sun, he found it [as if]
> setting in a spring of dark mud, and he found near it a people. Allah
> said, "O Dhul-Qarnayn, either you punish [them] or else adopt among
> them [a way of] goodness." ... Then he followed a way Until, when he
> came to the rising of the sun, he found it rising on a people for whom
> We had not made against it any shield.

as it is about zul-qarnayn went to time when the sun started to glow (past), *after* he went to time, when the sun falled to black hole (future).

any star, when starts to glow, [glows weakly][3] compared to how it glows later:

> Starting at zero-age main sequence, the proportion of helium in a
> star's core will steadily increase, the rate of nuclear fusion at the
> core will slowly increase, as will the star's temperature and
> luminosity. The Sun, for example, is estimated to have increased in
> luminosity by about 40% since it reached the main sequence 4.6 billion
> (4.6 × 109) years ago.


  [1]: https://islam.stackexchange.com/a/37137
  [2]: https://quran.com/18/83-93
  [3]: https://en.wikipedia.org/wiki/Star#Main_sequence