The number of confirmed planets frequently increases because as scientists analyse the data they are able publish their results online immediately. But as the finds are not yet peer reviewed, the total figure remains subject to change.
"Each night we get a list of astronomy papers where there might be an exoplanet announcement. When we get that we have to review it," explained Prof Mendez.
This exoplanet catalogue is organised by Jean Schneider, an astronomer at the Paris Observatory. For the past 18 years he has catalogued new exoplanets on the Extrasolar Planets Encyclopaedia.
Fuzzy planets Others in the field, like Prof Mendez, are then able to review and comment on the findings, which makes it "more dynamic" he explained.
"That's why the other catalogues just lag behind. The review is reliable as it's exactly the same as what the journals do." Prof Mendez told BBC News.
Nasa will only accept those announced in an academic journal, so it updates its list far less frequently. Their tally currently stands at 919 confirmed worlds.
Jean Schneider said it was also important to note that there was "no consensus for the definition of a planet" and that past experience had shown that a few objects declared as planets were actually artefacts or low-mass stars ( via bbc.co.uk ).