When was the first exoplanet discovered?

Answer 1

As of April 2009, 346 exoplanets are listed in the Extrasolar Planets Encyclopaedia. The vast majority have been detected through radial velocity observations and other indirect methods rather than actual imaging.

The first confirmed radial velocity detection was made in 1995, revealing a gas giant planet in a four-day orbit around the nearby G-type star 51 Pegasi.

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Answer 2

As of 27 April 2010, 453 planets have been discovered. All of them lie in the Milky Way. Exoplanets (Extrasolar) are those planets that orbit a star other than our own Sun.

Likely? trillions upon trillions upon trillions upon ... you get the idea.

See related link for up to date information of what has been detected.

Chronological update:

13th May 2010, there are 453 known exoplanets.

6th December 2010 there are 506 known exoplanets.

7th January 2011 - 519 planets

9th February 2011 - 528 planets.

13th April 2011 - 540 planets.

10 May 2011 548 planets

13 June 2011 555 planets

22 June 2011 563 planets

18 January 2012 725 planets

05 February 2012 758 planets

23 March 2012 763 planets

3 December 2013 1,049 planets

Answer 3

51 Pegasi became the first known exoplanet in the autumn of 1995.

After the announcement, on October 12, 1995, confirmation came from Dr. Geoffrey Marcy from San Francisco State University and Dr. Paul Butler from the University of California, Berkeley using the Hamilton Spectrograph at the Lick Observatory near San Jose in California.

51 Pegasi b (51 Peg b) is the first, and so far only, discovered planetary-mass companion of its parent star. (Further such companions would be designated c, d, and so on.) The planet has been informally named Bellerophon. After its discovery, many teams confirmed its existence and obtained more observations of its properties, including the fact that it orbits very close to the star, suffers estimated temperatures around 1200°C, and has a minimum mass about half that of Jupiter. At the time, this close distance was not compatible with theories of planet formation and resulted in discussions of planetary migration.

Answer 4

As of June 28, 2010, astronomers have made confirmed detections of 464 such planets.

Answer 5

The first confirmation of exoplanets occurred in 1992, two planets in orbit around a Pulsar PSR B1257+12.