i have found a new interpretation of quran 18:90 :

"Sahih International" translation :

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 time when the sun started to glow.

any star, when starts to glow, glows weakly 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.

i have found a new interpretation of quran 18:86-90 :

"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 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.