ScienceThe sun setting in a muddy spring (Qur'an 18:86)
The passage describes Dhul-Qarnayn travelling until he reaches the place where the sun sets, finding it descending into a muddy (or, in another reading, hot) spring. Read plainly, this reflects the ancient Near-Eastern picture of a sun that physically travels and sets in a specific earthly location — a picture we now know to be false. The sun is ~1.3 million times the volume of Earth and roughly 150 million km away; it does not arrive anywhere at dusk.
Believers respond: the verse describes what Dhul-Qarnayn saw (phenomenological language), not astronomy. The difficulty: the text says he found (wajadahā) it setting in the spring, and early commentators such as al-Tabari record that many read it literally. The phenomenological reading arrives after the astronomy does.