10 th planet has a Moon Jadwiga Daszyńska-Daszkiewicz Instytut Astronomiczny, UWr. 28 October 2005, Journal Club

July 30, an object larger than Pluto has been discovered in the Kuiper belt discovered in the Kuiper belt Team: Mike Brown (Caltech), Chad Trujillo (Gemini Obs.) David Rabinowitz (Yale Uni.) David Rabinowitz (Yale Uni.) Samuel Oschin Telescope at Palomar Observatory (48-inch) Brown, Trujillo, Rabinowitz,,Discovery of the planetary-sized object in the scattered Kuiper belt’’ astro-ph/ , submitted to ApJL, August 30, UB313

BASIC CHARACTERISTICS OF 2003 UB313  the largest known object in orbit beyond Neptun  the most distant object yet seen in the Solar System  currently near aphelion at 97.5  0.01 AU  4th brightest KBO  i = 43 o.993  0.001, e =   spectrum dominated by absorption due to methane

Basic characteriscts of 2003 UB313 The orbit of 2003 UB313

Relative reflectance of 2003 UB313

September 10, moon discovered orbiting 10th planet October 3, 2005 – the press announcement team of Mike Brown team of Mike Brown,,Satellites of the largest Kuiper belt object’’ Brown et al., submitted to ApJL, October 2, 2005 Keck II Telescope, Laser Guide Star Adaptive Optics system S/2005 (2003 UB313) 1 S/2005 (2003 UB313) 1

LASER GUIDE STAR ADAPTIVE OPTICS SYSTEM - allows to measures and correct for the aberrations of starlight - works similarly to natural guide star - instead of a natural bright star uses 589 nm laser light

Images of the four brightest KBO from Keck LGS AO

Keck Observatory image of 2003 UB313 and S/2005

Basic characteristics of S/2005  fractional brightness of satellite 0.02  apparent semi-major axis 0.53’’  true semi-major axis km  orbital period  14 days

Relative sizes and separations of 2003 UB313 and S/2005

Why is the discovery of the moon important ? MASS OF THE 10th PLANET THE HISTORY OF THE SOLAR SYSTEM