Compared to the sun, Earth is a fleck. You would need 109 of them to cover the sun's face and another 1.3 million to fill its interior. Yet puny Earth and all its sibling planets make their presence known with gravitational tugs that cause the mother star to wobble just a bit.

The shifts are revealed by analyzing changes in the light coming from the sun.

Planets' gravitational tugs become profoundly more difficult to detect if you are far away -- like in another solar system.

Nevertheless, scientists have charted 277 extrasolar worlds, though none as small as Earth. A new technique, described in this week's Nature, adds a formidable arrow to the planet-hunters' quivers.

filter laser pulses so that infinitesimally minute changes in starlight spectras can stand out

like looking at the reflection of trees, clouds and sky in a pool of standing water. Just as water is used to bear the images, laser light serves as the reflecting pond for analyzing starlight.

Earth-like planets doing the tugging