Extrasolar Planets
Read archived news from StarDate magazine.
During the past decade, astronomers have discovered far more planets outside our solar system — called extrasolar planets — than are located within it. Astronomers can not only detect a planet’s presence, they can deduce a lower limit to its mass and distance from its parent star, and the length of its year.
The most successful search method used to date is called the “radial velocity” method. As a star is tugged to and fro by a planet’s gravitational pull, astronomers measure a slight shift in the frequency of the star’s light.
“Astrometry” is another detection method. Its is sometimes called positional astronomy. Astronomers measure a star’s change in position on the sky, induced by the gravitational pull of a planet. They can use this information to calculate the planet’s mass and orbit.
If a planet passes directly between a star and an observer’s line of sight, it blocks out a tiny portion of the star’s light. This so-called “transit method” is used to look for predictable variations in this reduction of brightness and to reveal a planet’s presence.
A fourth possible detection method, called “gravitational microlensing,” comes from one of Einstein’s insights in his theory of general relativity: Gravity bends space. When a planet passes in front of a more-distant star, the planet’s gravity will behave like a lens to temporarily focus light from the star. This should cause a sharp increase in brightness and a change in the apparent position of the star. This method has yet to detect any planets.
Archived News
Trio of ‘Super-Earths’ Foretell Planet Finds
(September/October 2008)
Astronomers discover possible ‘water world’
(July/August 2007)
Spitzer
Delves into Atmospheres of Two Exoplanets
(May/June 2007)
Extrasolar
Planets Display Dazzling Array of Properties
(March/April 2007)
Beta
Pictoris Gives Up More Secrets
(September/October 2006)
Three Neptunes, Asteroid Belt Circle Southern Star
(July/August 2006)
Two Discoveries Reveal Diversity of Galaxy's Extrasolar Planets
(May/June 2006)
Telescope Ready to Listen for Cosmic 'Howdy-Do'
(March/April 2006)
Extrasolar Planet Update
(September/October 2005)
Hobby-Eberly Telescope Bags First Planet
(September/October 2004)
Spitzer Space Telescope Enters Planet Race
(September/October 2004)
Einstein Helps Planet Hunters
(July/August 2004)
Irritating Planet Heats Up Parent Star
(March/April 2004)
Planet-Making Recipe May be Easy to Whip Up
(September/October 2003)
8 New Planets Discovered
(March/April 2002)
Patient Observations Reveal Second Planet
(November/December 2001)
California Telescope Looks for Alien Flashes
(November/December 2001)
Satellite Discovers Evidence of Water in Distant Solar System
(September/October 2001)
Planetary Systems May Be Rare, Astronomers Report
(September/October 2001)
11 New Planets Discovered
(July/August 2001)
New Planets Challenge Theories
(Winter 2001 AAS meeting)
Giant Star May be Giving Birth to Planets
(Winter 2001 AAS meeting)
Padding New-Planet Portfolios
(July/August 2000)
First Extrasolar Planet Found Around Sun-Like Star
(July/August 1999)
Nearby Neighbor Joins Extrasolar Planets Roster
(September/October 1998)
Astronomers Find Possible Young Planetary Systems
(July/August 1998)
Warped Disk Around Nearby Star May Hide a Planet
(March/April 1998)
Planet May Orbit Neutron Star
(July/August 1997)
Planet or No Planet?
(May/June 1997)
The Planet Isn't be Homey, But How About Its Moons?
(March/April 1997)
» More information about extrasolar planets
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