How long can human life on earth

　　How long can human life on earth? Involving sustainable development strategy, it was the earth for human survival and development of any of the resources, also involved in the external environment of the earth will remain unchanged in many years.

　　According to the theory of modern astronomers, the sun will be sustained and stable to provide heat and light to the earth, , the earth around the sun, the average radius will remain unchanged for a long time, up to a tiny swing, this process will continue for at least 4 billion. For more than 4 billion years later, the earth shake a shake immediately & " . As for humans, but cannot afford the any shaking of the earth!The sun to the earth, however, continue to provide 40 million years of light and heat is no problem, because in the 40 million s, the consumed energy is less than 1% of the total sun! at least on the earth in a human can survive continuously in 40 million for the goal!.

　　The sun is the earth the most important factor in the external environment. how long can we live in the earth？