A new time frame for dinosaur demise and other science news Right next door?: Earth-like worlds may be closer and more plentiful than anyone imagined: Astronomers reported Wednesday that the nearest Earth-like planet may be just 13 light-years away - or some 124 trillion kilometres. That planet hasn't been found yet, but should be there based on the team's study of red dwarf stars. Galactically speaking, that's right next door. If our Milky Way galaxy were shrunk to the size of the United States, the distance between Earth and its closest Earth-like neighbour would be the span of New York's Central Park, said Harvard University graduate student Courtney Dressing, the study's lead author. Small, cool red dwarfs are the most common stars in our galaxy, numbering at least 75 billion. The research team estimates 6 per cent of red dwarf stars have Earth-like planets. "We now know the rate of occurrence of habitable planets around the most common stars in our galaxy," said co-author David Charbonneau in a release. That rate implies that it will be significantly easier to search for life beyond the solar system than we previously thought. These newest findings are based on data from NASA's Kepler space telescope, launched in 2009. They will be published in The Astrophysical Journal. - The Associated Press/Aleysha Haniff Dino death: Dinosaurs died off about 33,000 years after an asteroid hit the Earth, much sooner than scientists had believed, and the asteroid may not have been the sole cause of extinction, according to a study released Thursday. Earth's climate may have been at a tipping point when a massive asteroid smashed into what is now Mexico's Yucatan Peninsula and triggered cooling temperatures that wiped out the dinosaurs, researchers said. The time between the asteroid's arrival, marked by a 180-kilometre-wide crater near Chicxulub, Mexico, and the dinosaurs" demise was believed to be as long as 300,000 years. The study, based on high-precision radiometric dating techniques, said the events occurred within 33,000 years of each other. Other scientists had questioned whether dinosaurs died before the asteroid impact. "Our work basically puts a nail in that coffin," geologist Paul Renne of the University of California Berkeley said. He also said he believes ecosystems already were in a state of deterioration due to a major volcanic eruption in India when the asteroid struck. The study was published in the journal Science. - Reuters Not strictly science, but still a prime discovery: University of Central Missouri mathematicians have found the largest prime number ever identified. This 17,425,170-digit number was found last month. Primes are whole numbers such as 3, 7 and 11 that can only be divided evenly by themselves and 1. The number is the 48th known Mersenne prime - a specific type of rare prime number that's expressed as two to the power of "P" minus one. P itself is a prime number. For the new prime, P is 57,885,161. A single campus computer found the number on January 25, but it had to be verified by the prime number locator project known as GIMPS - the Great Internet Mersenne Prime Search. This is the third Mersenne prime identified at the university and Professor Curtis Cooper said this week he's starting again to find an even larger one. - The Associated Press and Reuters