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January 26, 2012

NASA Scientists Discover More Than Two Dozen New Exoplanets

by Jessica Berman

Twenty-six new exoplanets have been discovered by NASA scientists seeking to locate planets outside our solar system.  The alien planets were found orbiting stars in 11 newly discovered solar systems by the Kepler telescope, which the U.S. space agency operates.

The exoplanets range in size from slightly larger than Earth to larger than the gas giant Jupiter in our solar system.  They were discovered by Kepler, a space telescope which stares at 150,000 stars in a narrow sliver of the night sky from its perch orbiting the sun.

The alien planets orbit their host stars, which are bigger than the sun, once every six to 143 days.  The largest of the newly-discovered solar systems, called Kepler-33, hosts five exoplanets ranging in size from one-and-a-half to five times Earth’s size.

Doug Hudgins is the program scientist with the Kepler mission.  Hudgins says scientists do not believe any of the newly discovered exoplanets could support life.

“All of them are in orbits that are smaller than our Earth’s orbit around our sun.  So they would be fairly hot planets,” Hudgins said.

In the two years since the Kepler began observing the cosmos, scientists have discovered 61 exoplanets and some 2,300 candidate planets that need to be verified through further observations.

Kepler identifies exoplanets by continuously monitoring the brightness of a distant star in its narrow field.  A planet orbiting its host sun casts a faint shadow that is detected by Kepler.

The telescope confirms planetary candidates by measuring so-called Transit Timing Variations, or TTVs, which occur when two or more planets in a tightly packed solar system orbit their host stars.  

The gravitational pull of each passing planet causes one to speed up and another to slow down, according to Hudgins, helping astronomers confirm a planetary observation

“If you had something that was just mimicking a planet transit, they wouldn’t interact.  The fact that you see these transit timing variations tells us that there’s a gravitational interaction and that tells us that these really have to be planets because they are interacting with each other," Hudgins said.

Hudgins says the ultimate goal for planet hunters is a telescope that can separate the light of a dimmer planet from its bright star, allowing scientists to study its electromagnetic spectrum.  

The information gleaned from the light spectrum could tell astronomers what gases make up a planet’s atmosphere and possibly even some surface characteristics, according to Hudgins, who is anxious to find signs of life.  

“That’s why we do this.  That’s the exciting thing,  We are addressing one of the oldest and most fundamental questions of humankind.  And that is, are we alone?,” Hudgins said.

Hudgins believes such a telescope will be built in his lifetime, allowing Kepler scientists to move on to the next phase of their discovery mission.