by Kim Malville
The skies of November
November is a three-planet month, two of which can be viewed from Crestone. Mars is the bright planet visible at dusk low in the southwestern sky in the constellation of Sagittarius. It sets about 3 1/2 hours after the sun. Jupiter rises at 1am in the beginning of the month. By the end of November it will rise at 10pm. Jupiter is in Leo, about a fist-width at arm’s length from its brightest star, Regulus. It will dominate our evening skies by the end of the month. Mercury makes its appearance just before dawn during the first half of November. Unfortunately it will be hidden behind our mountains.
November 12: Rosetta spacecraft drops its lander, Philae, onto Comet CG. Wish it luck! An image of touchdown should arrive at earth at 9am MST.
November 17/18: The Leonid meteor shower will be best observed between midnight and dawn. These are some of the fastest meteors, hitting the earth head-on at 47 miles/hr. Perhaps you will see 12 meteors per hour. They radiate out from the constellation of Leo, where Jupiter resides this month.
November 25: Mars will be to the left of the crescent moon in the southwest about an hour after sunset.
Black holes & birth control
As galaxies age, they stop forming stars, even though there is lots of gas and dust out of which stars can be born. Most of these mature galaxies have super-massive black holes in their centers. These black holes pour energy into their galaxies, especially when unfortunate stars fall into their dread dark maws. Though the black hole will inevitably swallow some of this matter, a portion will be accelerated to speeds close to that of light and blasted away from the poles of the spinning black hole. This highly energetic stream of matter emits a powerful radio emission, which heats the gases throughout the host galaxy. Our own Milky Way galaxy has a black hole in its center. It is relatively modest, containing a mere 4 million stars like our sun. We are still producing babies, such as in the Orion Nebula, where there is a “stellar nursery.” Other galaxies have super-massive black holes of ten billion stellar masses or more. These are galactic contraceptives, acting like heating elements on a stove, keeping interstellar gases hot and shutting down star formation.
A comet buzzes Mars
Mars is the second most populated planet in the solar system, albeit populated by robots. We have five satellites in orbit and two rovers on the surface of Mars, all of which were watching this lump of ice and rock swing past. NASA’s Mars Reconnaissance Orbiter (MRO), MAVEN (Mars Atmosphere and Volatile EvolutioN) probe, a University of Colorado space mission, and Odyssey spacecraft appear to be in good health. They were positioned to hide behind Mars as Comet Siding Spring whizzed 87,000 miles past the planet at high speed. The three spacecraft and two rovers—NASA’s Curiosity and Opportunity—plus the two other probes at the Red Planet, were collecting information about the comet and its effect on Mars.
They succeeded in photographing a long-period comet’s pristine nucleus on its first foray into the inner solar system. This is the first time that a “fresh” comet from the Oort Cloud (a region surrounding the sun approximately a light-year away containing millions of unborn comets just waiting to drop toward the sun) has been observed up-close. All the other comets we’ve explored in the past with probes are short-period comets that have well-known orbits (like the famous Comet Halley). It is an incredible bit of serendipity that Siding Spring, which was only discovered in January 2013, should be so kind as to fly so close to a planet we have been populating with robots with cameras ready to start shooting.
Rosetta and its comet
The Rosetta spacecraft is scheduled to deliver its lander, Philae, to the surface of Comet Churyumov-Gerasimenko on 12 November. It is the first attempt at a soft touchdown on a comet: a truly historic event. Philae’s landing site, located on the smaller of the comet’s two bodies, was confirmed by the astronomers of the European Space Agency on 14 October following a comprehensive analysis of its surface. The highly irregular comet is quite different from the rounded, smooth-surfaced, potato-shaped object they had counted on.
Rosetta has been slowly moving closer to the comet, now caught in its weak gravity. By Oct 20 it was skimming just four miles from its surface. On November 12, Rosetta releases the lander, which will leisurely drift downward. Landing will be about seven hours later. It will attach itself to the comet by harpoons. Because of the great distance of the comet from the earth, the message, travelling at the speed of light, will take 28 minutes 20 seconds. Confirmation of touchdown will reach Earth at 9am MST.
Once safely on the surface, Philae will take a panorama of its surroundings. The first sequence of surface science experiments will begin about an hour after touchdown and will last for 64 hours. The major limitation on these experiments is the lifetime of Philae’s batteries. Further study of the comet by Philae will depend on how well the batteries are able to recharge, which in turn is related to the amount of dust that settles on its solar panels. Sometime around March 2015, as the comet moves closer in its orbit towards the Sun, temperatures inside the lander will have reached levels too high to continue, and Philae’s science mission will come to an end. The Rosetta spacecraft will continue on its extraordinary adventure, spiralling around the comet as it falls downward, coming closest to the sun in August 2015.