Microlensing

摘要

If you point a telescope at a star in the center of the galaxy and stare long enough, sooner or later a second star will pass in front of it. (Yes, it could take millions of years.) Depending on its mass and position, the foreground star can exert enough gravity to bend the light from the background star, acting as a lens. Such "microlensing" makes the background star appear brighter than usual.