Planet-Finding by Numbers

artist concept showing planet more than three times more massive than Earth Artist's concept of a planet 3.2 times more massive than Earth. This image is part of a graph that shows the number of potentially habitable planets the Space Interferometry Mission PlanetQuest would have the sensitivity to find. Click on the link below for the full graph. Image credit: NASA/JPL
› View full image
  • submit to reddit

October 18, 2006

More than a decade after the first planets beyond our solar system were found, astronomers have discovered about 200 of these "extrasolar planets," as they're called. Using a common-sense definition of potentially habitable planets, coupled with extensive computer simulations, scientists have calculated how many potentially habitable planets might be detected around other stars by the SIM PlanetQuest mission. ("SIM" stands for Space Interferometry Mission.)

The mission, scheduled for a launch in the next decade, will target planets with specific traits in common with Earth: a similar mass and an orbit in the "habitable zone," not too close and not too far from its parent star. With this mass and location, it's believed a planet could have liquid water on its surface and an atmosphere -- conditions considered necessary for life to gain a foothold.

The science team has shown that, in a survey of the best 120 candidate stars for hosting such planets, SIM PlanetQuest would have the sensitivity to find:

-- Planets smaller than Earth around six stars

-- Planets smaller than twice Earth's mass around 24 stars

-- Planets smaller than about triple Earth's mass around every star in the survey group

All planets discovered by the mission would be on a short list of targets for the future Terrestrial Planet Finder mission, which would look for direct signatures of habitable environments and even of life itself.

The roster of six stars where SIM PlanetQuest could find Earth-like planets, if they exist, includes some familiar names, visible in the nighttime sky:

-- Sirius, in the constellation Canis Major, the closest star visible with the naked eye from the northern hemisphere's mid-latitudes, seen in winter along a line extending from Orion's belt

-- Altair, forming one corner of the "Summer Triangle"

-- Alpha Centauri, the closest bright star to Earth, visible from southernmost Texas, Florida, Hawaii and the southern hemisphere

The research is contained in a paper published September 2006 in Publications of the Astronomical Society of the Pacific. Its authors are Joseph Catanzarite and Drs. Michael Shao, Stephen Unwin, Angelle Tanner, and Jeffrey Yu, all from JPL.

More information on SIM PlanetQuest is available at: http://planetquest.jpl.nasa.gov/SIM/sim_index.cfm .

Media contact: Jane Platt 818-354-0880
NASA's Jet Propulsion Laboratory

Images

artist concept of Sim PlanetQuest

Artist concept of Sim PlanetQuest. Image credit: NASA/JPL

enlarge image

drawing showing Sirius in the winter sky, northern hemisphere

Sirius, the closest star visible with the naked eye from the northern hemisphere's mid-latitudes, seen in winter along a line extending from Orion's belt. Image credit: NASA/JPL

enlarge image



Kepler-186f, the first Earth-size Planet in the Habitable Zone Leading Space Experts to Discuss the Search for Life Beyond Earth

› Read more

Planet with Twin Parent Stars Newfound Frozen World Orbits in Binary Star System

› Read more

A galaxy about 23 million light-years away is the site of impressive, ongoing, fireworks. Black Hole Fireworks in Nearby Galaxy

› Read more


Get JPL Updates
Sign Up for JPL UpdatesRegister today and receive up-to-the-minute e-mail alerts delivered directly to your inbox.
Sign Up for JPL Updates