For the first time, two teams of astronomers have been able to detect light from two planets outside our solar system.
One of the planets was discovered by a team led by David Charbonneau, assistant professor of astronomy at the Harvard-Smithsonian Center for Astrophysics. Drake Deming, chief of the Planetary Systems Laboratory in the NASA Goddard Space Flight Center, led the other team.
Astronomers refer to these new planets as extrasolar or exoplanets, Deming said.
“These planets are called extrasolar planets, which means that they orbit outside our solar system,” he said. “Extrasolar and exoplanet mean the same thing.”
The planet discovered by Deming’s team is known as HD209458b, and is approximately 150 light years from Earth, Deming said. The planet discovered by Charbonneau’s team is known by the scientific community as TrES-1, and is approximately 450 light years away from the Earth, Deming said.
“TrES-1 stands for Transatlantic Exoplanet Survey, because (there are) telescopes (set up) in the Canary Islands and in the United States,” Deming said.
Astronomers have been able to detect light from these planets, but little is known about the characteristics of the objects. Astronomers do know that they are extremely hot gaseous planets and have compared them to Jupiter.
“Unlike Earth, which gets its heat from the sun, the planets are 20 times closer to their stars, which is what makes them hotter,” Deming said.
Since 1995, approximately 130 planets outside our solar system have been discovered, but only their shadows have been observed.
“It’s like having 130 people in the room and only seeing their shadows,” Deming said. “Most of the planets were known to exist because of the wobble produced by gravity. We just didn’t know where.”
These planets were discovered by the Spitzer Space Telescope, which is capable of detecting heat from planets in the form of infrared light, Deming said.
“Spitzer works in two ways,” said Gordon Squires, assistant director of public affairs and an astronomer at the Spitzer Science Center. “First, the Spitzer measures the amount of light that is coming from the planet. Second, there is a special geometry that subtracts the light of the star from the light of the planet.”
The Spitzer is one of four telescopes in NASA’s Great Observatory, which is capable of looking into distant galaxies.
The Spitzer was not designed to detect new planets, and it came as a surprise to astronomers when it detected the planets’ light.
“It was a surprise that Spitzer would (find planets),” Squires said. “It was not designed to detect new planets, but now we see the possibility of using it for that purpose.”
For the scientific community, the discovery of these two objects is a step toward finding life in distant galaxies.
“Up until that moment, we had only seen light from the nine planets we know of,” Squires said. “Suddenly, we see two more planets. We were not able to do this until now.”
The Spitzer Space Telescope has been orbiting in space since 2003, and is scheduled for a five-year mission.
“The Spitzer mission will end in 2008,” Squires said. “So far, all indications show that it is working beautifully.”