But, in fact, they were also likely responsible for triggering terrestrial planet formation.

FORBES: Planets Made Easy: The Cosmic Glue That Binds Us All

There are two leading theories of planet formation.

WSJ: Possible New Planet Spotted Under Formation

The list of top discoveries made with Hubble reads like the hit parade of astronomy: a mysterious new "dark energy" causing the accelerating expansion of the universe, distances to other galaxies, the supermassive black holes at their centers, the age of the universe, planet formation around other stars, searches for signs of extraterrestrial life -- and the list goes on.

CNN: Space is still the new frontier

The system could thus provide astronomers with invaluable information about planet-disc interaction, suggests Alan Boss, a leading planet-formation theorist at the Carnegie Institution in Washington.

ECONOMIST: Astronomers may have stumbled on the birth of a solar system

Astronomers have long theorized that there are many planets that have drifted away from their home stars, whether it's a too-loose gravitational pull during the planet's formation or a stellar tug-of-war.

ENGADGET: University of Montreal detects an orbitless planet, shows that stars don't have an iron grip (video)

The film traces the unique geology of the area from the formation of the planet 4.6 billion years ago and how our rocks have driven and guided the jobs we do, the industries we support and our relationship with our local environment.

UNESCO: New film spotlights English Riviera Geopark

But the second planet may yield more valuable clues about the formation of solar systems and the universe.

CNN: Astronomers spy new neighbors outside solar system

"The results suggest that water was incorporated during the formation of Mars and that the planet was able to store water in its interior during the planet's differentiation, " Hauri said.

MSN: Scientists say parts of Mars interior are as wet as Earth's

The perceived problem is that for the first 600m years of its existence, the planet was being bombarded by bits of debris left over from the formation of the solar system.

ECONOMIST: The origin of life