THE massive asteroid YR4 now has a greater chance of smashing into Earth than any asteroid in history - as Nasa raises the risk level again.
Lewis said: “[The James Webb observations] will help us determine what we need to do about it, because if it’s a stony asteroid, that’s very different from a high proportion of iron-metal asteroid.
Scientists can also comb through old space data to study YR4 in observations when it was overlooked - work Lewis says space agencies around the world have already begun.
But the window of opportunity for astronomers to study the rock is closing, as the asteroid is expected to disappear behind the Sun in April.
The rock will pass nearby Earth in four years' time, but not close enough to cause alarm, when scientists will have another chance to gather data on it.
