What company are you calling from? http://aiapets.com/where-can-i-buy-levothyroxine-in-the-uk.pdf windy levothyroxine tablets buy uk mansion correctly They calculated that Earth's habitable-zone lifetime is as long as 7.79 billion years. (Earth is estimated to be about 4.5 billion years old.) Meanwhile, the other planets had habitable-zone lifetimes ranging from 1 billion years to 54.72 billion years.