by Kim Malville
Jupiter reigns supreme throughout the month, setting around midnight. It ceased its retrograde motion on January 30 and now glides smoothly to the east, moving away from the Pleiades, toward Aldebaran. Saturn rises about two hours after Jupiter sets.
February 1-10: The first ten days of February is a great time for observing the Zodiacal light, especially in the dark skies of Crestone. Look to the west about 80 minutes after sunset for a left-sloping pyramid of light. It is caused by sunlight scattered off the band of dust particles that surrounds the sun like an immense version of the rings of Saturn.
February 12-20: Great opportunities for viewing Mercury. It will be visible above the west-southwest horizon about 30 minutes after sunset.
February 15: An unnamed asteroid, between 130-160 feet in diameter, will make a close pass with the earth, coming within 18,000 miles of the surface of our planet at 12:25pm MST. Fear not: it is nearly certain that this asteroid will miss the earth. If it does hit us, we are in for a 2 megaton explosion.
February 17, 18: The Moon and Jupiter: The rapidly moving moon is to the right of Jupiter on the seventeenth and to its left on the eighteenth. Note the triangles formed on each of these night with Aldebaran, the red eye of Taurus. This beautiful sight is similar to what happened last month on the nights of January 21-22. If you missed it, here is a second chance!
February 28: Look for the moon and you will find nearby Spica, the brightest start of Virgo. In eastern Mexico to Central America Spica will disappear behind the moon.
The comets of 2013
This will be a fantastic year for comets, those dirty snowballs that in the past may have been responsible for depositing much of the water in our oceans (as well as those that once existed on Venus and Mars). The most spectacular comet, Comet ISON, has been described as the comet of the century and should arrive in our skies in December. Discovered by two Russian astronomers in September 2012, far beyond the orbit of Jupiter, it appears to be a sun grazer (like Comet McNaught of 2007), passing through the sun’s corona on November 28. If it emerges, it may be as bright as the moon, visible in daylight.
Before it arrives, another comet, PanSTARRS will appear in our western skies around twilight in the week of March 12-18. This comet’s orbit indicates that it is a newcomer to the inner solar system, falling in from the Oort comet cloud where billions of its kind have been living in icy hibernation for more than four billion years.
The ice lakes of Titan
Those who are still smarting over the ejection of Pluto from the ranks of planets should take heart by the fact that the most interesting objects in our solar system (excepting Earth, of course) are not planets but their moons. The most fascinating moon of them all is freezing-cold Titan, Saturn’s largest moon. With a diameter of 3,200 miles and a temperature of -297°F, it is the only body in our solar system apart from Earth known to possess stable bodies of liquid on its surface. While Earth’s weather cycle is based on water, Titan’s involves hydrocarbons. Liquid ethane and methane fall as snow and rain, forming large lakes and seas. Recent measurements of Titan by the Cassini space craft indicate icebergs of methane floating in these cold seas. One of the most intriguing possibilities is that they might host a truly alien form of life, with an entirely different chemistry than ours, on the boundary between liquid and solid. Such a boundary may have been important for the origin of terrestrial life.
Hydrocarbon ice should float in the moon’s seas, as long as the temperature is just below methane’s freezing point and the ice is at least 5% air, which is the average composition for young sea ice here on Earth. Those conditions will change with the seasons on Titan. The Cassini spacecraft’s extended stay in the Saturn system provides a fascinating opportunity to watch the effects of seasonal change of Titan. The $3.2 billion Cassini mission, a joint effort of NASA, the European Space Agency and the Italian Space Agency, was launched in 1997 and arrived at Saturn 2004. It will continue to observe the ringed planet and its more than sixty moons through at least 2017.
Black Beauty landed in Morocco
A dark lump of rock found in the Moroccan desert in 2011 has turned out to be the oldest meteorite that has arrived from Mars. Weighing 320g, the stone was purchased from a Moroccan meteorite collector and has been nicknamed “Black Beauty”. There are over 110 Martian meteorites currently in collections worldwide. They were all blasted off the surface of the red planet, probably by asteroid impacts, and then spent millions of years travelling through space before falling to Earth. Their discovery has been mostly by chance. A few were seen in the act of falling. Their dark forms have caught the eye of meteorite hunters who scour desert sands for these rare rocks that can often sell for tens of thousands of dollars. Many have been found in Antarctic glaciers, where they have been concentrated by the flow of ice. Needless to say, this method of collecting rocks from Mars is enormously cheaper than sending a manned mission to that planet.
All the other Martian meteorites were crystallized 200-400 million years ago, while Black Beauty dates to 2.1 billion years. Its chemical composition is remarkably similar to that measured by the Mars rover Spirit in Gusev Crater. The rock also has 10 times more water than other Martian meteorites, adding to the evidence that water was once abundant on the surface of Mars. Today’s cold, dry planet with a thin atmosphere appears to have been a lot warmer and wetter. The original water on Mars may have come from volcanic eruptions or falling comets. After its volcanoes ceased erupting and the rain of comets stopped, water escaped into space because of its low gravity. Personally, I hope there was sufficient time for primitive life to have gained a foothold.