The Milky Way could be spreading life from star to star

For almost two centuries, scientists have theorized that life may be distributed throughout the universe by meteoroids, asteroids, planetoids, and other astronomical objects. This theory, known as Panspermia, is based on the idea that microorganisms and the chemical precursors of life are able to survive being transported from one star system to the next.

Expanding on this theory, a team of researchers from the Harvard Smithsonian Center for Astrophysics (CfA) conducted a study that considered whether panspermia could be possible on a galactic scale. According to the model they created, they determined that the entire Milky Way (and even other galaxies) could be exchanging the components necessary for life.

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Life on our planet might have originated from biological particles brought to Earth in streams of space dust, a study suggests.

Fast-moving flows of interplanetary dust that continually bombard our planet’s atmosphere could deliver tiny organisms from far-off worlds, or send Earth-based organisms to other planets, according to the research.

NASA held a news conference Feb. 22 at the agency’s headquarters to discuss the finding by the agency’s Spitzer Space Telescope of seven Earth-sized planets around a tiny, relatively nearby, ultra-cool dwarf star. Three of the planets in this system, known as TRAPPIST-1, are in the habitable zone – the region around the star in which liquid water is most likely to thrive on a rocky planet.

This is the first time so many planets have been found in a single star's habitable zone outside our solar system, and is the best target yet for studying the atmospheres of potentially habitable, Earth-sized worlds.

TRAPPIST-1 is an ultra-cool dwarf star. Over 21 days, Spitzer measured the drop in light as each planet passed in front of the star. Spitzer was able to identify a total of seven rocky worlds, including three in the habitable zone where life is possible.

The study established the planets' size, distance from their sun and, for some of them, their approximate mass and density.

It also established that some, if not all, these planets are tidally locked, meaning one face of the planet permanently faces their sun.