Exoplanet Exploration: PlanetQuest Historic Timeline

Exoplanet Exploration: NASA PlanetQuest Historic Timeline

The NASA interactive multimedia timeline traces the search for extrasolar planets, from ancient philosophical speculation to modern discoveries.

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Exoplanet Exploration: Planet Quest Key Milestones

• 450 B.C.: Greeks ponder the existence of other worlds
• 1750: Wright describes the Milky Way as a massive disk of stars
• 1992: Woszczan and Frail discover rocky planets
• 1995: Mayor and Queloz find a planet at 51 Pegasi
• 1999: First transiting exoplanet observed
• 2005: Spitzer observed direct light from an exoplanet
• 2008: First visible-light exoplanet images released

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Are we alone? Searching for Earthlike Worlds

For centuries, human beings have pondered this question. Medieval scholars speculated that other worlds must exist and that some would harbor other forms of life. In our time, advances in science and technology have brought us to the threshold of finding an answer to this timeless question.

The recent discovery of numerous planets around stars other than the sun confirms that our solar system is not unique. Indeed, these "exoplanets" appear to be common in our galactic neighborhood.

The exoplanets we have discovered so far are giants, like Jupiter and Saturn. They are unlikely to support life as we know it. But some of these planetary systems might also contain smaller, terrestrial planets like Mars and Earth.

Over the next 15 years, NASA is embarking on a bold series of missions to find and characterize new worlds. These will be the most sensitive instruments ever built, capable of reaching beyond the bounds of our own solar system.

The Keck Interferometer combines the light of the world's largest optical telescopes, extending our vision to new distances. Using a technique known as interferometry, the Keck will study dust clouds around stars where Earthlike planets may be forming.

NASA's Kepler Mission, scheduled to launch in 2009, will survey our region of the Milky Way galaxy to detect and characterize hundreds of Earth-size and smaller planets. It will tell us whether planets like Earth are common or rare in our galaxy.

SIM PlanetQuest, to follow Kepler, will measure the distances and positions of stars with unprecedented accuracy. SIM's precision will allow us to locate planets in the habitable zones around nearby stars.

Finally, the Terrestrial Planet Finder will build upon the legacy of all that have gone before it. With an imaging power 100 times greater than the Hubble Space Telescope, the Terrestrial Planet Finder observatories will provide the first photographs of nearby planetary systems.

We will analyze the atmospheres of these distant worlds, looking for carbon dioxide, water and ozone. The substantial presence of all three gasses would suggest that life is present. Such a discovery would at last provide convincing evidence that we are not alone. We will have found another Earth.

Follow the history of planet hunting from science fiction to science fact with NASA's PlanetQuest Historic Timeline at http://planetquest.jpl.nasa.gov/timel...

The interactive PlanetQuest web feature, developed by JPL, conveys the story of exoplanet exploration through a rich tapestry of words and images spanning thousands of years, beginning with the musings of ancient philosophers and continuing through the current era of space-based observations by NASA's Spitzer and Kepler missions. The timeline highlights milestones in culture, technology and science, and includes a planet counter that tracks the pace of exoplanet discoveries over time.

• More information about exoplanets and NASA's planet-finding program: http://planetquest.jpl.nasa.gov
• 3D New Worlds Atlas - A visual guide to exoplanets: http://planetquest.jpl.nasa.gov/atlas...

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Related videos:

NASA/Spitzer Hidden Universe (Episode 4): Night And Day On An Alien World
• http://www.youtube.com/watch?v=tvOq2b...

NASA/Spitzer Hidden Universe (Episode 16): The X-Planets
• http://www.youtube.com/watch?v=8WXbVi...

Hubblecast 12: An Extrasolar Planet's Atmosphere
• http://www.youtube.com/watch?v=VDmvr4...

Hubblecast 14: Organic Molecules On Extrasolar Planets
• http://www.youtube.com/watch?v=Lxs9Pm...

ESOcast 11: Exoplanets Galore - 32 New Extrasolar Planets Found
• http://www.youtube.com/watch?v=UcJuhE...

ESOcast 18: Exoplanet Caught On The Move
• http://www.youtube.com/watch?v=JDTXno...

The Webb Space Telescope (JWST): Finding Earth-like Planets
• http://www.youtube.com/watch?v=r8eYB_...

Hubble's Universe Unfiltered (Episode 7): Eye Spy A Planet - Extrasolar Planets
• http://www.youtube.com/watch?v=8Ou6kk...
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