Planet-Finding by Numbers

Oct 18, 2006
Planet-Finding by Numbers
This graph shows the number of potentially habitable planets the Space Interferometry Mission PlanetQuest would have the sensitivity to find. Image credit: NASA/JPL

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 star immortalized in the movie "Contact" and 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: planetquest.jpl.nasa.gov/SIM/sim_index.cfm .

Source: by Jane Platt, NASA's Jet Propulsion Laboratory

Explore further: What's happening in the universe right now?

add to favorites email to friend print save as pdf

Related Stories

Technology improves avalanche gear for backcountry skiers

1 hour ago

As outdoor recreation companies increasingly cater to skiers and snowboarders who like to venture beyond the groomed slopes at ski resorts and tackle backcountry terrain, they've put a special emphasis on gear and equipment ...

The elephant poaching business in numbers

1 hour ago

From the pittance paid to local poachers to a multi-billion dollar industry, here are some of the key numbers related to Africa's endangered elephants:

UN moves toward major treaty for ocean biodiversity

1 hour ago

UN member states agreed Saturday to begin negotiations on a treaty to protect marine biodiversity in ocean areas extending beyond territorial waters, in a move heralded by environmental organizations.

Recommended for you

What's happening in the universe right now?

4 hours ago

There are some topics that get a little frustrating in their pedantry, but can really draw attention to the grand scope and mechanics in our Universe. This is definitely one of them.

The tell-tale signs of a galactic merger

Jan 29, 2015

The NASA/ESA Hubble Space Telescope has captured this striking view of spiral galaxy NGC 7714. This galaxy has drifted too close to another nearby galaxy and the dramatic interaction has twisted its spiral ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.