The 6th Imam, Ja’afar Ibn Muhammad el Sadiq(AS) was Born in Madinah on 17th Rabiul Awwal 83 Hijiri (23.4.702 AD). Died in Madinah on 15th Shawwal, 148 Hijri (7.12.765 AD) at the age of 63. Period of Imamat 34 years.
It is known from various history books and various sources of Hadith that when Imam Sadiq was a young boy, he used to come to the schools and Madrasas founded by his father the 5th Imam and instead of learning as many other youngsters and older pupil did, he used to discuss serious matters of Fiqh and Jurisprudence with much older students of the Madrasas. In one such discourses when he was only 11 years old, when he entered a class room where pupils were discussing on the subject of astronomy, he pointed out to the surprise of everyone except his own father, that the earth cannot be flat, because of the way the sun rises in the East and sets in the west and day and night change in 24 hours, it cannot be possible. In his opinion the earth must be round, otherwise this would not have happened in such a precise manner. All the students were astonished but his father smiled and said nothing.
The above story was mentioned in a book compiled by Five French scholars at Strasbourg in France with the title,”The heart of the Sh ia Scholarship.” The book has been translated in Persian and Urdu and it is now being translated in English with possible references.
source : http://www.al-islam.org