You may not know that nearly every year a handful of asteroids skim past Earth at distances that are startlingly close in astronomical terms.
Apophis, an asteroid with an estimated diameter of almost three football fields (270m), will make its close approach to Earth this week.
The asteroid sample will help scientists understand the origin of organics and water that may have seeded life on Earth 4.5 billion years ago.
The good news that Tholen came up with is that the estimated probability of asteroid Apophis colliding with Earth in 2036 has been reduced from 1 chance in about 45,000 to 1 chance in about 250,000.
If the nearly 275-metre-wide Apophis passes through a narrow gravitational keyhole in April 2029, it will be on course for a massive collision seven years later, most likely on April 13, 2036, the scientists said.
