Distantly Orbiting Alien World May Challenge Planet Formation Theories
This graphic shows a gap in a protoplanetary disk around the nearby red dwarf star TW Hydrae. At left is a Hubble Space Telescope image showing a gap about 7.5 billion miles away from the star; the graphic at right shows the gap relative to the star.

Astronomers have found evidence of an alien planet forming surprisingly far from its host star, a discovery that could challenge the prevailing wisdom about how planets take shape.

Researchers using NASA's Hubble Space Telescope spotted a large gap in the planet-forming debris disk surrounding the red dwarf star TW Hydrae, which lies about 176 light-years from Earth in the constellation Hydra (The Sea Serpent).

This gap, which was likely carved out by an unseen newborn exoplanet six to 28 times as massive as Earth, sits 7.5 billion miles (12 billion kilometers) from TW Hydrae - about twice the distance from our own sun to Pluto. [The Strangest Alien Planets]

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