The Mars Global Surveyor is lost after having operated for over a decade, sending 240,000 images back to Earth, and, says Mike Meyer, NASA’s lead scientist for Mars exploration, having greatly exceeded all expectations. The MGS has experienced a broken stabilizer wing, failed gyroscope, and a worn-out gear wheel since its launch in November 1996.

Still, it has sent back stunning evidence for an active geology on Mars including gullies apparently formed by water, rock erosion, and polar caps consisting of dry ice evaporating rapidly. On Nov. 2, the MGS reported difficulties with its solar panel array and sent a last garbled message five days later before falling silent. Attempts to spot the MGS with the Mars Reconnaissance Orbiter to see whether the solar energy panels were pointed away from the sun failed, and it is likely that nothing more will be heard from it, but the MGS has provided material for years of study by planetary scientists.

Focus on the planets

Planet watchers in December will be treated to an extremely close pairing of Mercury, Mars, and Jupiter low in the southeast about an hour before sunrise. The rare Dec. 10 conjunction finds the three planets in a tight circle measuring about 1 degree in diameter. This is the closest pairing of the trio since 1974.

Mercury can be spotted very low in the southeast about a half-hour before sunrise at midmonth.

Venus is very low in the southwest and sets only a half-hour after the sun as the month opens. By the end of December, Venus has risen higher and remains in view for over an hour. However, its position on the far side of the sun from Earth makes for meager viewing opportunities.

Mars is growing dimmer but may be spotted around midmonth sandwiched between Jupiter to the upper right and Mercury to the lower left of the Red Planet.

Jupiter is well up on the southeastern horizon about an hour before dawn, the brightest of the three planets in the morning sky.

Saturn is well up on the eastern horizon around midnight during the first week of December. The bright star directly beneath is Regulus. The tilt of Saturn’s rings is not particularly favorable for viewing but several of its moons can be spotted by telescope.

Neptune and Uranus are in the southwest as darkness falls. Neptune is so low it may not be visible, but Uranus should be visible with binoculars and with the aid of a finder’s chart.

December events

5 Full moon, 7:24 p.m. The full moon of December is called the Long Night Moon or the Moon Before Yule.

9 Saturn is directly below the waning moon around 11 tonight. The bright star below is Regulus.

10 Jupiter, Mercury and Mars are in a close-knit circle of less than a degree on the southeastern horizon this morning. Look for them about an hour before dawn.

12 Moon in last quarter, 9:32 a.m.

13 The moon is at apogee or farthest distance from Earth.

14 Geminid meteor shower peaks from high overhead in Gemini and could produce more than 100 sightings an hour if conditions are right. The Geminids are typically slow moving, bright and do not leave a persistent trail.

18 The sun enters Sagittarius on the ecliptic. Look to the southeastern horizon about an hour before daybreak where Mercury, Mars and Jupiter form an ascending line. The thin crescent moon will be to the trio’s right.

20 New moon, 9:00 a.m.

21 Winter solstice, 7:25 p.m. This is when the sun is farthest south of the equator, marking the start of winter in the northern hemisphere.

22 Tonight is the peak night for the Ursid meteor shower. Fainter and fewer in number than the Geminids, the Ursids average about 10 meteors an hour, but the recent new moon assures a dark sky for viewing. The sun enters the astrological sign of Capricornus but astronomically has just entered Sagittarius. Tonight may be the first night you will be able to see Venus peeking above the southwestern horizon as it returns to the night sky for winter.

25 Merry Christmas!

27 Moon in first quarter, 9:48 p.m.

28 Moon at perigee or nearest approach to Earth for the second time this month.

31Check the southeastern horizon about an hour before daylight where Jupiter, with Mars far to its lower left, and the bright red-orange star Antares to the lower right make up a neat celestial triangle.

Sunrise, 7:13 a.m.; sunset, 4:04 p.m.