Exoplanet discovery

Scientists at the European Southern Observatory, or ESO, announced the discovery of the richest known extrasolar planetary system on Tuesday. After six years of study, ESO published its findings that at least five confirmed exoplanets, or extrasolar planets, are orbiting a star only 127 light years away from Earth.

The five exoplanets all have approximately the mass of Neptune - between 13 and 25 times the mass of Earth - but orbit much closer to their star, with orbital periods between six and 600 days (Neptune takes 164.79 years to orbit the Sun).

In addition to the five Neptune-sized planets, ESO astronomers have "tantalizing" evidence of two more exoplanets in the system. One is Saturn-sized, with an orbital period of 2,200 days and the other is the smallest known exoplanet with merely 1.4 Earth masses and an orbital period of only 1.18 days.

The Sun-like star, which is called HD 10180, is located in the southern constellation Hydrus, and has been studied closely since its discovery with the HARPS spectrograph in La Silla, Chile. The existence of the exoplanets was discovered through gravitational wobbles in the behavior of the star caused by the passage of the planets.

Familiar traits observed

Using data from this new discovery as well as data from other planetary systems, the researchers found evidence of the Titius-Bode law that exists in our solar system: The distances of the planets from their star seem to follow a regular pattern.

"This could be a signature of the formation process of these planetary systems," team member Michel Mayor said in the ESO press release.

ESO astronomer Christophe Lovis also acknowledged that this discovery highlights the changes in the field of exoplanet research.

"We are now entering a new era in exoplanet research: The study of complex planetary systems and not just of individual planets," Lovis said. "Studies of planetary motions in the new system reveal complex gravitational interactions between the planets and give us insights into the long-term evolution of the system."

Through further study of the system around HD 10180, ESO astronomers hope to learn more about planetary formation and about how the solar system was developed, as well as what its future may look like.

Author: Stuart Tiffen (AP/AFP)

Editor: Kate Bowen