This year, Dr Madhusudhan and colleagues published the first measurements of the exoplanet's radius.
Nevertheless, exoplanet surveys are providing real data to a field long starved of them.
P-1 is the second exoplanet that is much bigger and less dense than theory predicts.
The Transiting Exoplanet Survey Satellite, which aims to do just that, could be approved by NASA next year.
ECONOMIST: Extra-terrestrial life: Closer to encounter | The
NASA, plans to launch a more ambitious exoplanet-hunter, called Kepler, in October 2008.
Such an arrangement would have quickly shed its protoplanetary discs, so how exactly the exoplanet came to be formed is a mystery.
Kepler flags exoplanet candidates via the transit method, which looks for dips in a star's brightness caused by an object crossing in front of it.
Just a fortnight ago, astronomers using the Hubble space telescope identified water vapour in the atmosphere of an exoplanet, albeit a gaseous exoplanet some 150 light years away.
Nevertheless, Kepler 22b is the most promising exoplanet yet found.
The light from the planet was detected in infrared form by the Spitzer Space Telescope, which also detected the first light from another exoplanet, the gas giant HD 209458 b.
They have used similar observations of more distant stars to find "exoplanets" (planets orbiting stars other than the sun) and in a few rare cases, to measure characteristics of the exoplanet atmospheres.
"Eso's La Silla Observatory on the outskirts of the Atacama Desert is certainly one of the best astronomical sites in the world, " said Michael Gillon, who leads the exoplanet survey for Trappist.
One of the key presentations at the conference was given by Dr Giovanna Tinetti who's leading the Exoplanet Characterisation Observatory, or EChO, mission recently selected for further development by the European Space Agency.
"Assuming that 1:10, 000 are similar to the Earth would give us 5, 000, 000 such planets, " added Tuomi, who led teams reporting the discovery of several potentially habitable planet candidates this year, including an exoplanet orbiting the star Tau Ceti just 11.9 light-years from Earth.
One of five European Space Agency missions being considered for launch in the early 2020's, Nasa also has a series of exoplanet projects at various stages of development, and both the James Webb Space Telescope and ground based observatories are getting in on the act.
Dubbed the Transiting Exoplanet Survey Satellite (or TESS), this new space telescope will one-up Kepler with the ability to perform an all-sky survey (an area 400 times larger than previous missions) to search for transiting exoplanets, with an eye towards planets comparable to Earth in size.
ENGADGET: NASA gives planet-hunting TESS space telescope go-ahead for 2017 launch
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