Astro News Briefs: April 7–13

Jupiter Gains Six in "Moon Race"...

April 9, 2003 | The surge of satellite discoveries around giant Jupiter continues, with six new ones chalked up in February and announced late last week. Each mountain-size moonlet, roughly 2 kilometers across, is traveling in a distant, "irregular" orbit having a large eccentricity and inclination. Two competing teams of observers have been scrambling to sweep up small, undiscovered Jovian satellites; for February's finds both teams used the 3.6-meter Canada-France-Hawaii Telescope on Mauna Kea — sometimes taking turns at the controls on the same night — and both recorded all six moonlets. Three of the newfound objects, designated S/2003 J13 through J15, are credited to Scott S. Sheppard and David C. Jewitt (University of Hawaii), along with Jan Klenya (Cambridge University). The other three, S/2003 J16 through J18, go to a four-observer group led by Brett Gladman (University of British Columbia). Jupiter's satellite count now stands at 58, more than half of which have been found so recently that officials with the International Astronomical Union have yet to assign them permanent names.

Sheppard provides more information on Jupiter's satellite family at http://www.ifa.hawaii.edu/~sheppard/satellites/

For a tabulation of all known moons see SkyandTelescope.com's Guide to Planetary Satellites


...And Saturn Gains One

April 9, 2003 | Having scrutinized most of the celestial real estate around Jupiter, the observing team of Scott S. Sheppard and David C. Jewitt (University of Hawaii) have moved their satellite hunt outward to Saturn. Together with Jan Klenya (Cambridge University), they discovered the ringed giant's 31st known satellite on February 5th using the 8.3-meter Subaru telescope on Mauna Kea. As calculated by Brian G. Marsden (IAU Minor Planet Center), who has computed preliminary orbits for many of Jupiter's newly found moonlets, S/2003 S1 occupies a highly inclined and eccentric orbit that averages 19.1 million kilometers from Saturn and takes 989 days to complete. With the discovery of this object, estimated to be about 5 km across, the number of known moons in our solar system now stands at 125.

More details on the discovery appear at http://www.ifa.hawaii.edu/~sheppard/satellites/sat2003.html


COMMENT