Scientists at Harvard’s Center for Astrophysics are celebrating the discovery of the smallest known exoplanet—a planet orbiting a star other than the Sun—announced Tuesday by European astronomers.

The new planet, Gliese 581 e, is 1.9 times the size of Earth and 80 times smaller than the first exoplanet, which was discovered in 1995. The solar system where the planet was found is 20.5 light years away and can be found in the constellation Libra.

Members of the CFA, which has played a major role in the search for exoplanets, heralded the discovery as momentous.

“This discovery can be compared to what happened 400 years ago with Galileo’s discovery of Jupiter’s moons,” said Dimitar Sasselov, a professor of astronomy. “It is amazing that it happened on the 400th anniversary of Galileo’s discovery.”

At the Center, many scientists are heavily involved with exoplanet research. Harvard astrophysicists have developed one of the most “exciting” techniques in the search for exoplanets, known as the transit method, which is currently being utilized by the National Aeronautics and Space Administration’s Kepler Mission, Sasselov said.

NASA’s Kepler telescope is designed to find Earth-like planets around other stars.

“Harvard is very much involved [with Kepler], providing the scientific backing for the mission,” said Sasselov.

Scientists said that they are optimistic about Kepler’s potential to uncover more planets beyond our Solar System.

“Kepler may actually detect Earth-like planets,” said CFA scientist Scott J. Kenyon, who added that the search for Earth-like planets is a major goal of exoplanet research.

“We’re trying to find lower and lower mass planets that are more and more similar to the earth,” Kenyon said.

Harvard’s new Origins of Life Initiative will bring together research in exoplanets and other areas of physical science with research in the life sciences, according to Sasselov.

Students interested in this topic have the option of learning more from courses such as Science A-54: Life as a Planetary Phenomenon and the recently approved course Astronomy 110: Exoplanets.