Extra-Solar Planets
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The Search for Extra-Solar Planets
One of the largest projects going on in space exploration today is the search for and discovery of planets orbiting other stars. These planets are what scientists refer to as extra-solar planets or exo-planets. At present, there has been over 4,000 of these planets discovered ranging in size from Jupiter-sized or larger down closer to Earth-sized or even smaller. As techniques for finding these extra-solar planets improve, whole solar systems with many planets will be discovered. And with more planets being found, the more opportunities there will be to find intelligent life in the universe.
The Discoveries
Extrasolar planets were thought to exist by scientists for years but it wasn't until October 6, 1995 that the first extrasolar planet was discovered to be orbiting a sun-like star known as 51 Pegasi in the constellation Pegasus. Since then, planets have been discovered orbiting stars such as 70 Virginis in the constellation Virgo, 55 Cancri in Cancer, Tau Bootes in Bootes, 16 Cygni in Cygnus and around many other stars including some red dwarfs. All told, the current extrasolar plant count stands at 4,375 confirmed with 3,247 stars having planets orbiting them. There are also 5,856 extrasolar candidates listed many of which may be confirmed as actual planets. The number of terrestrial type planets discovered such as our planet Earth stands at 163.
In discovering extrasolar planets, one of the methods scientists use makes use of the fact that when a planet orbits a star, the planet's gravitational pull causes the star to wobble slightly. When the star wobbles toward the Earth, its lightwaves are shifted to the blue end of the light spectrum or blue shifted. When the star wobbles away from the Earth, its lightwaves are shifted toward the red end of the spectrum or red shifted. Scientists examine these differences in wavelengths and can determine the planet's size and orbital characteristics. This method is called the radial velocity method. Other methods are also being used in extrasolar planet detection such as astrometry which uses the precise measurement of a star as compared to backround stars. There is also the direct detection method where scientists must cancel out the light of the star to be able to detect the planet. Today, the most used method to detect extrasolar planets is the transit method which measures the periodic diming of a star by a planet passing in front of it. As scientists improve their methods to detect these planets orbiting other stars, many more will be discovered. The future for discovering new worlds certainly looks exciting
For more information on extrasolar planets, visit these websites
1. Exoplanet Exploration: Planets Beyond Our Solar System
2. Giant Planets Orbiting Faraway Stars
3. Kepler & K2
5. List of Exoplanetary Host Stars
6. List of Multiplanetary Systems
7. Other Worlds, Distant Suns - A Catalog of Extrasolar Systems
8. Planetary Habitability Laboratory - Habitable Exoplanets Catalog
9. The Extrasolar Planet Encyclopedia
10. The Search for Extrasolar Planets
11. Transiting Exoplanet Survey Satellite (TESS)
Extra-Solar Planet News
Can We Spot Volcanoes on Alien Worlds? Astronomers Say Yes - Harvard-Smithsonian Center for Astrophysics - September 7, 2010
Using Planet Colors to Search for Alien Earths - NASA News Topics Report - November 2, 2010
NASA's Spitzer Reveals First Carbon-Rich Planet - Caltech News Release - December 8, 2010
NASA's Kepler Mission Discovers Its First Rocky Planet - NASA News Report - January 10, 2011
Earth-Like Planets Orbit Nearby Red Dwarfs Stars, Say Scientists - Space.com You Tube Video - February 6, 2013
Alien Planet Found Orbiting Star That's Just Like Our Sun (Video) - Huffington Post.com - January 15, 2014
Super-Habitable World May Exist Near Earth - Astrobiology.com News report - March 14, 2014
Astronomers Discover First "Ice Giant" Exoplanet - Planet Quest News - October 24, 2014
NASA's Spitzer Spots Planet Deep Within Our Galaxy - NASA/JPL News - April 14, 2015
Circular Orbits Identified for Small Exoplanets - MIT News - June 1, 2015
Mars-size Planet Orbits Distant Star - Planet Quest News - June 17, 2015
NASA's Spitzer Maps Climate Patterns on a Super-Earth - NASA Press Release - March 30, 2016
A Planet 1,200 Light-Years Away is a Good Prospect for a Habitable World - UCLA Newsroom - May 26, 2016
Potentially Habitable Planet Found Orbiting Star Closest to Sun - National Geographic - August 24, 2016
SOFIA Confirms Nearby Planetary System is Similar to Our Own - NASA Press Release - May 2, 2017
Four Earth-Sized Planets Found Orbiting the Nearest Sun-Like Star - Keck Observatory News - August 9, 2017
Exoplanets: Worlds Beyond Our Solar System - Space.com - March 29, 2018
Discovery Alert: A Record Haul Planet Count Hits 4,000 - Exoplanet Exploration - Planets Beyond our Solar System - June 13, 2019