Sign prayer
The signs prayer (Arabic: صلاة الآيات, romanized: Ṣalāt al-ʾĀyāt) is a Muslim prayer that is optional for Sunni but mandatory for Shīʿa Muslims. When solar or lunar eclipses, earthquakes, thunder, or other natural phenomena (described as signs, hence the name signs prayer) occur, Muslims may have to pray Ṣalāt al-ʾĀyāt.