In the world of exoplanets (and all of science really), one has to be very careful and very sure of what one is publishing. Researchers were very sure and very excited when they discovered what looked like a planet around the star Fomalhaut. Totally looked like an open-and-shut case: they took a picture of Fomalhaut with the Hubble Space Telescope in 2004 and then again in 2006 and saw that there was a spot that moved! This gave us the infamous “Eye of Sauron” picture :)
Astronomers love this exoplanet because it is one of the VERY FEW (like 7) planets we actually have images of. All of the other ones are found through somewhat indirect means – transiting and star wobble (we’ll extensively discuss in class). But for Fomalhaut-b, all subsequent images have been unable to find the spot again :( Finally, it seems the infrared Spitzer Space Telescope has nailed the coffin shut… It took a picture and the exoplanet is not there. The exoplanet SHOULD be very bright in the infrared because it is hot. But it is not there.
Bad Astronomer Phil Plait gives a great overview of the topic here and at the bottom of the post has a FANTASTIC little slideshow gallery detailing the planets we ACTUALLY have images of (all 7 of them).
These things happen – new information comes along and we have to re-think all stuff before it. I’ll be interested to see how Wikipedia gets updated with the new information :) The entries for Fomalhaut, Fomalhaut-b, and exoplanets will all need to modified at least :)