"So when the stars are effaced," meaning: God's punishment will descend on the day when the stars are effaced, and their light will vanish.
﴿فَإِذا النُّجُوم طمست﴾ أَيْ: يَنْزِلُ عَذَابُ اللَّهِ يَوْمَ تُطْمَسُ فِيهِ النُّجُومُ، فَيَذْهَبُ ضَوْؤُهَا
