When there was a solar eclipse the Messenger of Allah (way peace be upon him) observed eight ruku's and four prostrations (in two rak'ahs). This has been narrated by 'Ali also.
Sahih Muslim Book 10, Hadith 20
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Sahih Muslim Book 10, Hadith 19 Next Hadith → The Apostle of Allah (ﷺ) observed prayer while it was (solar) eclipse. He recited (the Qur'an in qiyam) and then bowed. He again recited and again bowed. He again recited and again bowed and again recited and again bowed, and then prostrated; and the second (rak'ah) was like this.

Sahih Muslim Book 10, Hadith 21