Spitzer Space Telescope: Earth's Dust Trail may Point To Alien Worlds

It's extremely challenging - and usually impossible - to directly image exoplanets. They're relatively small and faint, hiding in the glare of the stars they orbit.

"A dust tail like Earth's could produce a bigger signal than a planet does. And it could alert researchers to a planet too small to see otherwise."

Earth has a dust tail not because the planet itself is particularly dusty, but rather because the whole solar system is. Interplanetary space is littered with dusty fragments of comets and colliding asteroids.

When Earth orbits through this dusty environment, a tail forms in the rear, akin to swaths of fallen leaves swirling up behind a streetsweeper.

"As Earth orbits the sun, it creates a sort of shell or depression that dust particles fall into, creating a thickening of dust - the tail - that Earth pulls along via gravity," explains Werner. "In fact, the tail trails our planet all the way around the sun, forming a large dusty ring."

Spitzer's recent observations have helped astronomers map the structure of Earth's dust tail and figure out what similar "tell-tale tails" attached to alien planets might look like.

Read more at the JPL Spitzer website