Hi All

Mike Brown has added more information about Planet X and clarified what's known about the other two big KBOs his team have been observing, EL61 and FY9...

Planet Lila

...and 'Lila', like 'Xena', is not the name suggested to the IAU - they've stayed traditional and are suggesting something mythical. Apparently both Persephone and Persipina are both already taken by minor planets, so they've cast the name net further afield.

The upper limit on size is ~ 3550 km since that's the maximum radius consistent with a negative detection by the Spitzer Space Telescope. If its albedo is like Pluto's - as the near-IR suggests - then it'll be about +2850 km across. The spectra do differ however and Planet X is greyer than Pluto, so it might actually be bigger. Brown has been saying ~ x 1.5 times Pluto.

There's some more info at the Gemini web-site...

Planet X

...Mike Brown also discusses how they were almost scooped by someone who had looked up their preliminary data posted online and apparently had used the IAU's MPC ephemeris generator to do their own observation plot - thus Brown and colleagues rushed to a press conference to scotch a possible "discovery" announcement by parties unknown.

It's a shame that people could be so underhanded.

Adam