Humans may be justifiably nervous when an asteroid passes very close to Earth, but a new study finds that the encounter leaves the asteroid pale and shaken as well.
Examining differences in the color of asteroids, University of Hawaiʻi at Mānoa Astronomers Schelte Bus and Alan Tokunaga observed that those with the paler color characteristic of fresh, unweathered rocks had passed very close to Earth.
When the loose conglomeration of rocks and boulders that comprise an asteroid passes our planet, it is shaken by the changing pull of Earth’s gravity, causing landslides that cover dark weathered areas with fresh rocks, Bus suggests. “Hence the asteroid’s color, after the encounter, will appear paler than before.”
“The more we learn about what holds an asteroid together, the better chance we have to reduce or eliminate damage to Earth from an asteroid strike,” adds Tokunaga, an Institute for Astronomy associate director.