Carl Edward Sagan was an American astronomer, cosmologist, astrophysicist, astrobiologist, and author. He developed an interest in astronomy quite early at the age of five he first learned that the sun was actually a star and all stars are as big as the sun. Much later, while studying at Chicago University, he came to know that astronomers make good money. All along, he had been pursuing astronomy as a hobby; now he was glad to know that he could take it up as his profession. Thereafter, he earned his Ph.D. in astrophysics, and after a brief period of fellowship at the University of California, he took up a teaching position, first at Harvard University and then at Cornell. Concurrently, he was also appointed a visiting scientist at NASA. Although he was a renowned scientist, working on planetary atmospheres, in astrobiology, and on the origin of life, he is best known for his work on extraterrestrial life. He also worked tirelessly to popularize science, authored many papers and books, and regularly took part in television programs. All these made him the most known scientist in the 1970s and 1980s.