Mercury - starts December well displayed in the morning sky, but by mid-month begins sinking into the glare of the Sun.

Venus - becomes visible in the evening sky during December. Look for it 5 to 10 degrees up in the SW just after sunset starting at mid-month. Venus will be magnitude -3.8 and have an apparent diameter of 10".

Mars - now rising more than an hour before the Sun, is low in the southeast at dawn.

Jupiter - enters the morning sky this month. Look for it low in the SE about 45 minutes before sunrise. On the morning of December 10, Mercury and Mars will be within 1 degree of Jupiter. The 2nd magnitude star Beta Scorpii will be nearby as well. This group will be about 5 degrees above the SE horizon during mid-twilight.

For detailed postions of Jupiter's Moons try this interactive javascript utility.

Saturn - located in Leo, the ringed planet rises by 10 pm EST at mid-month and reaches the meridian by 4:30 am. Saturn will then be 63 degrees up in the south. Saturn will be 0.3 magnitude during December with an apparent diameter of 19 to 20 arc-seconds. The rings will be 41 arc-seconds across and tilted 12 degrees to our line-of-sight.

The Cassini spacecraft continues its observation of Saturn and its many moons and rings. For the latest images from Cassini, see:

http://saturn.jpl.nasa.gov/home/index.cfm

For detailed postions of Saturn's Moons try this interactive javascript utility.

Uranus - located in Aquarius. Look for it 40 degrees up in the south around 6 pm EST at mid-month. Uranus will be less than 1 degree SW of 3rd magnitude Lamba Aqr during December. At magnitude 5.9, Uranus can be glimpsed with the naked eye from a moderately dark site. Through a telescope, Uranus has a 3.5" greenish disc.

A finder chart for Uranus can be found on page 66 of the May issue of Sky & Telescope.

Neptune - located in Capricornus. Look for it 25 degrees up in the SW around 6 pm EST at mid-month. At magnitude 7.9, Neptune can be seen with binoculars but a telescope is needed to see its 2.2" pale blue disc.

A finder chart for Neptune can be found on page 66 of the May issue of Sky & Telescope.

Pluto - is now in the Sun.

A finder chart for Pluto can be found on page 66 of the May issue of Sky & Telescope.

Eris (pronounced "EE-ris") - formerly known as Xena, 2003 UB313, and "the tenth planet"  is magnitude 19 in central Cetus, high in the south during evening.

Geminid Meteor Shower - peaks on the nights of December 13-14. Usually about 50 to 100 Geminids can be seen every hour from a dark site, radiating from an area near Castor and Pollux. This year, the waning crescent Moon will not interfere with meteor watching. Since Gemini rises during the early evening, many Geminids can be seen before midnight.