List of exoplanet firsts

This is a list of exoplanet discoveries that were the first by several criteria, including:

• the detection method used,
• the planet type,
• the planetary system type,
• the star type,

and others.

The first

The choice of "first" depends on definition and confirmation, as below. The three systems detected prior to 1994 each have a drawback, with Gamma Cephei b being unconfirmed until 2002; HD 114762 b is near the boundary of exoplanet / brown dwarf mass; while the PSR B1257+12 planets orbit a pulsar. This leaves 51 Peg b (discovered and confirmed 1995) as the first confirmed exoplanet around a normal star.

Title	Planet	Star	Year	Notes
First detected exoplanet later confirmed	Gamma Cephei Ab	Gamma Cephei	1988 (suspected), 2002 (Confirmed)	First evidence for exoplanet to receive later confirmation.
First exoplanets to be confirmed	PSR B1257+12 B PSR B1257+12 C	PSR B1257+12	1992	First super-earths.[1] However, these exoplanets orbit a pulsar rather than a normal star.
First confirmed exoplanet around normal star	51 Pegasi b	51 Pegasi	1995	First convincing exoplanet discovered around a Sun-like star.[2] While the minimum mass of HD 114762 b was high enough (11 Jupiter-masses) that it could be a brown dwarf, 51 Peg b's minimum mass meant that it almost certainly was near the mass of Jupiter.

By discovery method

First discovery by a method

Title	Planet	Star	Year	Notes
First planet discovered via pulsar timing	PSR B1257+12 B PSR B1257+12 C	PSR B1257+12	1992	First super-earths.[1]
First planet discovered via radial velocity	51 Pegasi b	51 Pegasi	1995	First convincing exoplanet discovered around a Sun-like star.[2] While the minimum mass of HD 114762 b was high enough (11 Jupiter-masses) that it could be a brown dwarf, 51 Peg b's minimum mass meant that it almost certainly was near the mass of Jupiter.
First planet discovered via transit	OGLE-TR-56 b	OGLE-TR-56	2002	[3] This was also the second planet detected through transiting,[3] and the then farthest planet known at time of discovery.[3] The first extrasolar planet discovered to be transiting was HD 209458 b, which had already been discovered by the radial velocity method.[3][4]
First planet discovered via gravitational lensing	OGLE-2003-BLG-235L b	OGLE-2003-BLG-235L / MOA-2003-BLG-53L	2004	This was discovered independently by the OGLE and MOA teams.[5]
First exoplanet discovered by directly imaging the extrasolar planet	2M1207 b	2M1207	2004/ 2005	May be a brown dwarf instead of a planet, depending on formation mechanism and definitions chosen.[6]
First planet discovered through variable star timing	V391 Pegasi b	V391 Pegasi	2007	The planet was discovered by examining deviations from pulsation frequency from a subdwarf star.[7]
First extrasolar planet discovered by indirect imaging (visible light)	Fomalhaut b	Fomalhaut	2008	Discovered by a light reflecting off of a dust cloud surrounding the planet.[8] First planet orbiting an ABO star.
First extrasolar planet discovered by astrometric observations	HD 176051 b	HD 176051 A or HD 176051 B	2010	Orbits around one of the stars in a binary star system although it is not known which component it is orbiting around.
First exoplanet discovered by orbital perturbations of another planet	Kepler-19c	Kepler-19 (KOI-84, TYC 3134-1549-1)	2011	Detected through transit-timing variation method. Its existence was inferred by the gravitational influence it had on the orbital periodicity of Kepler-19b.[9][10]
First exoplanets discovered by orbital phase reflected light variations	Kepler-70b, Kepler-70c [11]	Kepler-70	2011
First exoplanet discovered by transit-duration variation method	Kepler-88c	Kepler-88 (KOI-142)	2013	Both transit timing variation and transit-duration variation was measured to measure deviations from the regular orbit of Kepler-88b. Deviations of the planet's transit duration and timing helped to discover Kepler-88c.[12]

By detection method

First detection by a method

Title	Planet	Star	Year	Notes
First planet detected via pulsar timing	PSR B1257+12 B PSR B1257+12 C	PSR B1257+12	1992	[1]
First planet detected via radial velocity	51 Pegasi b	51 Pegasi	1995	[2]
First planet detected by transit method	HD 209458 b	HD 209458	1999	This first exoplanet found to be transiting had already been discovered by the radial velocity method. This is also the first planet that has been detected through more than one method.[3][4]
First directly imaged extrasolar planet (infrared)	2M1207 b	2M1207	2004	May be a sub-brown dwarf instead of a planet, depending on formation mechanism and definitions chosen. If it is a planet, it is the first known planet around a brown dwarf.
First planet with observed secondary eclipse (infrared)	HD 209458 b	HD 209458	2005	Planet was discovered in 1999. This is the first detection of light from an object with a clear planetary origin.
First directly imaged extrasolar planet orbiting a 'normal' star (infrared)	DH Tau b	DH Tau	2005	[13] Revised masses place it below the deuterium-burning limit. May be a brown dwarf companion.
First extrasolar planet detected through polarimetry	HD 189733 b	HD 189733	2008	Could not be confirmed. Possibly a "Saharan dust event over the La Palma observatory in 2008 August".[14] HD 189733 b was discovered in 2005.
First directly imaged extrasolar planet orbiting a sun-like star (infrared)	1RXS J160929.1−210524 b	1RXS J160929.1−210524	2008	[15] Revised mass places it at or above the deuterium-burning limit. May be a sub-brown dwarf instead of a planet, depending on formation mechanism and definitions chosen.
First planets directly characterized through astrometric observations	Gliese 876 b and Gliese 876 c	Gliese 876	2009
First planet detected by orbital phase reflected light variations in visible light	CoRoT-1b[16]	CoRoT-1	2009	The planet in question had already been discovered with transit method.
First planets detected through ellipsoidal light variations of the host star	HAT-P-7b	HAT-P-7b	2010	[17]
First planets detected through transit timing variation method	Kepler-9b, Kepler-9c	Kepler-9	2010	Transit-timing variation was used to confirm both planets detected through transit method.[18]
First planet detected through transit duration variation method	Kepler-16b	Kepler-16	2011	Orbital motion of the stars causes transits of both components of Kepler-16 to deviate significantly.
First planet detected with eclipsing binary timing with well-characterized orbit	Kepler-16b	Kepler-16	2011	Kepler-16b itself was detected through transit method. There are stars with earlier detections through eclipsing binary timing. However, either those signals have matched with unstable orbits or the exact orbits are not known.[19]
First planet detected by light variations due to relativistic beaming	TrES-2b	TrES-2	2012	[20]
First tilted multi-planetary system discovered	Kepler-56b, c and d	Kepler-56	2012 (b, c) 2013 (d)	First tilted multiplanetary system discovered.

By system type

First discovery by system type

Title	Planet	Star	Year	Notes
First extrasolar planet discovered in a solitary star system	PSR B1257+12 B PSR B1257+12 C	PSR B1257+12	1992	First extrasolar planets discovered.[21] HD 114762 b was discovered in 1989, but was not confirmed as a planet before 1996.
First "free-floating" planet discovered[NB 1]	S Ori J053810.1-023626 (S Ori 70)	N/A	2004	[22] Has a mass of 3 MJupiter; needs confirmation.
First planet discovered in a multiple main-sequence star system	55 Cancri b	55 Cancri	1996	55 Cnc has a distant red dwarf companion. The planet around Gamma Cephei was already suspected in 1988. Gamma Cephei Ab is the first relatively close binary with a planet.
First planet discovered in a circumbinary orbit	PSR B1620-26 b	PSR B1620-26	1993	Orbits a pulsar and a white dwarf. Discovery confirmed in 2003.
First multiple planet extrasolar system discovered	PSR B1257+12 A PSR B1257+12 B PSR B1257+12 C	PSR B1257+12	1992	First pulsar planetary system.
First multiple planet system in a multi-star system where multiple planets orbit multiple stars	Kepler-47b Kepler-47c	Kepler-47	2012	[23][24] NN Serpentis cataclysmic variable is suspected to have at least 2 planets as of 2009.[25]
First planet discovered in globular cluster	PSR B1620-26 b	PSR B1620-26	1993	Located in Messier 4.
First binary star system where both components have separate planetary systems	HD 20781 b HD 20781 c HD 20782 b	HD 20781 HD 20782	2011

Title	Planet	Star	Year	Notes
No star system
First non-stellar planet	S Ori J053810.1-023626 (S Ori 70)	N/A	2004	[22]
Single star system
First planet in a solitary star system.	PSR B1257+12 B PSR B1257+12 C	PSR B1257+12	1992	[21]
Binary star system
First planet in a binary star system	55 Cancri Ab	55 Cancri	1996
First planet in a single-star orbit in a binary star system	55 Cancri Ab	55 Cancri	1996
First planet in a circumbinary orbit in a binary star system	PSR B1620-26 b	PSR B1620-26	1993	The existence of the planet was confirmed in 2003.
First planet in a circumbinary orbit in a binary star system around main-sequence stars	Kepler-16b	Kepler-16	2011	The stars have spectral classes K and M.
Trinary star system
First planet in a trinary star system	16 Cygni Bb[26][27]	16 Cygni	1996	The stars in this system are 16 Cygni A, 16 Cygni B and 16 Cygni C.
First planet in a single star orbit in a trinary star system	16 Cygni Bb[26][27]	16 Cygni	1996	16 Cygni A and Cygni C form a main pair with the semi-major axis being 73 AU. 16 Cygni B orbits 877 to 15,180 AU from the barycenter of the A and C pair.
First planet in a multi-star orbit in a trinary star system
First planet in a circumbinary orbit in a trinary star system
First planet in a triple-star orbit in a trinary star system
Quadruple star system
First planet in a quadruple star system	PH1 or Kepler-64b	Kepler-64	2012	[28]
First planet in a multi-star orbit in a quadruple star system	PH1 or Kepler-64b	Kepler-64	2012	[29]
First planet in a single-star orbit in a quadruple star system	30 Arietis BA b	30 Arietis BA	2009	Quadruple nature of the system was revealed in 2015.[30]
First circumbinary planet discovered in a quadruple star system	PH1 or Kepler-64b	Kepler-64	2012	[29]

By star type

First discovery by star type

Title	Planet	Star	Year	Notes
First pulsar planet discovered	PSR B1257+12 B PSR B1257+12 C	PSR B1257+12	1992	[21][1]
First known extrasolar planet orbiting a main sequence star (Sun-like)	51 Pegasi b	51 Pegasi	1995	First hot Jupiter.[21]
First known planet orbiting an ABO star (blue-white star)	Fomalhaut b	Fomalhaut	2008	First extrasolar planet discovered by visible light image.
First known planet orbiting a red dwarf	Gliese 876 b	Gliese 876	1998	[31][32]
First known planet orbiting a giant star	Iota Draconis b	Iota Draconis	2002	Aldebaran b was announced in 1997, but was not confirmed until 2015.
First known planet orbiting a white dwarf.	PSR B1620-26 b	PSR B1620-26	1993	GD 66 b was announced in 2007, but has not been confirmed.
First known planet orbiting a brown dwarf.	2M1207 b	2M1207	2004	May in fact be a sub-brown dwarf instead of a planet, depending on formation mechanism and definitions chosen. First directly imaged planet.
First "free-floating" planet discovered[NB 1]	S Ori J053810.1-023626 (S Ori 70)	N/A	2004	[22] Has mass of 3 MJupiter; needs confirmation.

By planet type

Firsts by planet type

Title	Planet	Star	Year	Notes
First hot Jupiter	51 Pegasi b	51 Pegasi	1995	First planet discovered orbiting a main sequence star.
First extrasolar terrestrial planet orbiting a main sequence star	Mu Arae c	Mu Arae	2004	Terrestrial nature of this planet is not confirmed, as no radius measurements are available so the density is unknown. The minimum mass is comparable to that of Uranus, which is not a terrestrial planet. The first extrasolar planet known to have a density compatible with being a rocky planet is CoRoT-7b.
First super-earth discovered[NB 2]	PSR B1257+12 B PSR B1257+12 C	PSR B1257+12	1992	[21] First planets discovered.[21]
First super-earth orbiting a main sequence star[NB 2]	Gliese 876 d	Gliese 876	2005	Orbits a red dwarf star.
First icy extrasolar planet orbiting a main sequence star	OGLE-2005-BLG-390Lb	OGLE-2005-BLG-390L	2006	Orbits a red dwarf star. The icy nature of this planet is not confirmed, as no radius measurements are available so the density is unknown. The first extrasolar planet known to have a density compatible with being an icy planet is GJ 1214 b, though even for this case there are other possibilities for the composition.
First evaporating planet discovered	HD 209458 b	HD 209458	1999	First transiting planet.[21]
First Jupiter analogue	HIP 11915 b	HIP 11915	2015	First gas giant located in outer planetary system of another star; previous gas giants had been discovered, but all closer to their star. The discovery raises the possibility that HIP 11915 will be the first Solar System analogue discovered.
First ocean planet candidate; also first planet within the circumstellar habitable zone	Gliese 581d	Gliese 581	2007	Orbits a red dwarf star. This planet orbits a little too far from the star, but the greenhouse effect would be enough to make this planet habitable. The other ocean planet candidate, GJ 1214 b, was detected by transit in which the density was calculated and determined that this planet is an ocean planet.
First "free-floating" planet discovered[NB 1]	S Ori J053810.1-023626 (S Ori 70)	N/A	2004	[22] Has mass of 3 MJupiter; needs confirmation.

Other

Other firsts

Title	Planet	Star	Year	Notes
First extrasolar transiting planet	HD 209458 b	HD 209458	1999	[4] OGLE-TR-56 b is the first planet found by transit method.[3]
First map of an extrasolar planet released	HD 189733 b	HD 189733	2007	The map in question is a thermal emission map.[33]
First multi-planet extrasolar system directly imaged	HR 8799 b HR 8799 c HR 8799 d HR 8799 e	HR 8799	2008
First planet discovered with a retrograde orbit	WASP-17b	WASP-17	2009	The planet HAT-P-7b was discovered before WASP-17b, but its retrograde nature was announced after that of WASP-17b.
First extrasolar planet with serious potential to support life	Gliese 581g	Gliese 581	2010	This planet may be tidally locked to its parent star, but there could be a habitable band along the terminator. The other candidate is Kepler-22b.
First planet discovered orbiting a Sun-like star in a star cluster	Pr0201b Pr0211b	Pr0201 Pr0211	2012	Beehive Cluster star cluster.[34]
First recorded planet-planet transit	Kepler-89d Kepler-89e	Kepler-89	2012	Kepler-89e was partially transiting Kepler-89d.[35]
First transiting planet discovered in a star cluster	Kepler-66b Kepler-67b	Kepler-66 Kepler-67	2013	NGC 6811 star cluster; these two planets were, at the time of discovery, only two of six total planets known in star clusters.[36]
First map of cloud coverage of an extrasolar planet	Kepler-7b	Kepler-7	2013	Observations indicate cloud coverage in the west and clear skies in the east.[37]
First not tidally locked extrasolar planet to have its day length measured	Beta Pictoris b	Beta Pictoris	2014	Rotation speed was calculated to be 8.1 hours.[38]
First extrasolar planet system with one transiting and one directly imaged planet	PTFO 8-8695 / CVSO 30 b CVSO 30 c	CVSO 30	2016
First planet found to contain water in the stratosphere	WASP-121b	WASP-121	2017	[39][40]

See also

• List of exoplanets
• List of exoplanet extremes
• Most earth-like exoplanets

Notes

1. Free-floating objects are not usually considered planets
2. The mass range of Super-Earths is disputed

References

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