"I came to know of it at Trivandrum airport but could not believe it until Prime Minister Manmohan Singh spoke to me over phone. I thanked him and said I am extremely grateful (to his government)," he told reporters at Bangalore international airport on his arrival from Thiruvananthpuram.
"This has come to me as a complete surprise", said Rao, who has 60 honorary PhDs to his credit in a glorious scientific career spanning more than five decades.
Rao said he has worked very hard to earn such a recognition and owed the Bharat Ratna to his wife, family and young people who worked with him.
"The future of India are the young people. I owe a lot to the young generation who have worked with me and also my wife and family," he added.
Rao said India rewards hard working people, not those who lack qualities of dedication and hard work. "In India, if you work hard you will get major results. If we don't work hard enough and don't dedicate (yourself, you will not achieve anything)," he said.
Rao said he did not expect he would scale great heights when he decided to become a scientist 60 years ago, studying at Banaras Hindu University.
"I did not realise my country will bestow me with Bharat Ratna today," he said.
Talking about his teachers, Rao said the best of the lot were his school and high school teachers.
To a question, Rao said felt nuclear scientist Homi Bhabha should have been given the coveted award.
To another question, Rao said India should take a cue from China, which is investing a lot in the development of science. "Like China, India should invest in people, institution and science," he added.
On Sachin Tendulkar getting Bharat Ratna too, Rao said, "He is a great cricketer and I only say (it is) wonderful."
Indu, Rao's wife, also did not believe the news initially. "I said it can't be true. We were seated at Trivandrum airport when an employee came to us and said there was an urgent phone for my husband. I thought it was a family call because my son stays here, but turned out be a very important call," she said.
Asked how she felt on her husband's achievement, Indu said, "I don't feel any different. I am the same old person. Students are my children. Every time I invite them home for dinner. I have been doing it for 53 years."
On Rao commending her for her support for reaching such heights, Indu said, "It is my privilege. God has given me such an opportunity that I have been married to him."
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