Splashdown!

The Huygens probe will reach the surface of Saturn's largest moon, Titan, this month. The probe is too small to see with an earth based telescope, of course, but Saturn and Titan will be perfectly placed for observers to take a look while contemplating the spacecraft's mission, to show Saturn and its moons to the public while explaining about the mission, or merely to "space out" staring at the prettiest planet in our sky. Saturn rises shortly before sunset, so it will be high in the sky most of the night, with its rings tilted about 22 degrees to us.

Assuming the mission is going as planned, Huygens separated from the Cassini orbiter on Christmas eve, at 6pm our time, and has been falling toward Titan ever since. It will enter Titan's atmosphere on January 14 at 3am, the day after Saturn's opposition, traveling at about 5 meters per second (about 11mph); then it will deploy parachutes to slow its descent, and will spend the next two and a half hours drifting slowly down to Titan's surface. Will it splash into a liquid ocean, or smash into rock or ice? Whatever it finds, its instruments will radio the results to the Cassini orbiter, which will relay them back to Earth.

Jupiter rises around midnight. It makes two close passes with the moon this month, and actually is occulted for some southern hemisphere observers, but here in San Jose we won't see them pass closer than about a degree.

Mars rises just before dawn. Later this year we will enjoy another good Mars opposition, but now it's at the far side of its orbit from us, just a tiny speck showing little detail to an earth-based telescope. Pluto rises about the same time as Mars, not early enough for there to be much hope of spotting this faint and distant planet.

Mercury and Venus are very close to the sun in the morning sky. Ambitious early morning observers might want to try to spot them on the mornings of the 12-14, when Mercury passes less than half a degree south of Venus.

Neptune is too close to the sun to be seen this month. Uranus sets a few hours after sunset, so this pale green disk is still a target, especially at early evening public star parties.