12/30/2004
January Skies - by Dick Cookman
Highlights: Comet Journal, Martian Landers, Planet Plotting, Quadrantid Meteor Shower, January Moon
Focus Constellations: Cassiopeia, Aries, Triangulum, Perseus, Auriga and Taurus
Comet Journal
In January, Comet Machholz (C/2004 Q2) moves through Taurus and eastern Aries, and bypasses Triangulum. It then plunges through Perseus into Cassiopeia. It will appear immediately west of the Pleiades Star Cluster on the 7th and may approach 4th magnitude. The tail could actually envelope the cluster!
On the night of the 16th it will pass Algol, the Demon Star in Perseus, and its tail will probably cover much of NGC 1275, the adjacent dim (13th magnitude) elliptical galaxy. Although it will reach maximum extent at perihelion on January 24th when it's closest to the Sun, viewing will be best in the first half of the month when glare from the new and waxing Moon will be minimal.
The comet's orbit is almost perpendicular to that of the Earth. During its current passage by the Sun, Comet Machholz travels from below Earth's orbit and in early January, ascends through our orbital plane, 1.2 AU's from the Sun, just beyond Earth's position in late December. It continues northward and will dim drastically after March as it rises further above the plane of the inner solar system and retreats from the Sun.
Martian Landers
On its 295th day on Mars, "Opportunity" resumed its travels. It backed away from Burns Cliff which Dr. Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for the rover instruments, described as follows: "In the lower portion of the cliff, the layers show very strong indications that they were last transported by wind, not by water like some layers higher up. The combination suggests that this was not a deep-water environment but more of a salt flat, alternately wet and dry."
The rover moved 18.2 meters toward its original entry point into Endurance Crater. The panoramic imaging conducted on Sol 296 revealed a possible shortcut out of the crater, but closer examination after traveling another 8.6 meters on Sol 297 indicated that the original entry route offered higher probability of success. During the exit trip, "Opportunity" conducted detailed studies of two additional rocks, "Paikea and Wharenhui." The rover then completed its 181 day mission of observing layered bedrock within Endurance Crater when it climbed out on Sol 315.
Perched on the edge of the crater, "Opportunity" will now resume exploration of the Meridiani region's broad plains. On Sol 319 (Dec. 17th,) it moved about 40 meters toward the heat shield ejected during entry, which crash landed about 200 meters from Endurance Crater. Examination of the heat shield and the fresh crater produced by its impact should indicate how the heat shield performed during atmospheric entry, and reveal the nature of the subsurface in the new crater.
From the edge of the Endurance Crater, "Opportunity" has already observed frost and cirrus clouds associated with the transition in Martian seasons. From its position just south of the equator, the rover is recording moisture migrating from the warmth of the northern hemisphere summer to the wintry southern hemisphere.
So far on its mission, "Opportunity" has discovered copious evidence for water on the ancient surface of Mars. Near the landing site, the layered bedrock contains cross-bedding consistent with deposition in moving water. The lower (older) layers have abundant iron- and magnesium-bearing minerals probably deposited as a result of evaporation of the water in which they were originally dissolved. The upper (younger) rocks contain sulfate minerals (jarosite) typical of deposition in acidic water bodies. Observation of rocks within the ancient crater indicates that surface water existed through a very long time period in virtually every location.
On August 31st, its 223rd day on Mars, "Spirit" discovered goethite in a rock called "Clovis," which it examined at the base of the West Spur of Columbia Hills. Goethite forms only in the presence of water, either in liquid, ice or gaseous form. Afterwards, the rover crossed the West Spur and continued its eastern ascent into the hills despite sticky brakes which cause current demand to be excessive. Whenever slopes permit,
"Spirit" is instructed to drive backwards so that it can drag the malfunctioning right front wheel.
Spirit is northeast of "Machu Picchu," and has crossed a 200 foot wide saddle between the hills and West Spur and, on Sol 332 (Dec. 14th,) approached "Larry's Lookout" during ascent of "Husband Hill". The rover examined a number of rocks including "Corn," "Cocomama," "Butter," and "Wishstone," and the occasional rest periods permitted the lubricant in the wheel to be redistributed, allowing the current use to return to normal. Periodic rest days will be included in future rover plans, and Spirit will alternate between forward and backward driving to keep the lubricant in all of the wheels more evenly distributed. After completing examination of "Wishstone" on Sol 337, the next two days were spent driving 14 meters out of an attempted 40 meters over a sandy surface which tilted about 15 to 20 degrees and caused slippage which approached 80%. The drive was halted when a potato-size rock became jammed in the rover's right rear wheel which then became buried by maneuvers to free the wheel. "Spirit" finally extricated itself before Christmas on Sol 345 (Dec. 23rd.)
Planet Plotting
Mercury makes a little counter-clockwise turn around Venus in the southeastern sky before sunrise in the first half of January. Mercury (-0.4 magnitude) is a little more than 1.0° northwest of a much brighter Venus (-3.7 magnitude) in Ophiuchus on the 1st, a little less than 1.0° to the west on the 8th and 0.3° south-southwest of Venus in Sagittarius at 8 PM EST on the 13th. The closest approach that we should be able to see (weather permitting!) will be before dawn on the 14th. In the latter part of the month, Mercury rapidly descends into sunrise and Venus soon follows its neighbor.
Mars is a member of the dawn brigade for the entire month. It leaves the grasp of the claws of Scorpius at the beginning of January and moves passed its brighter counterpart, the red supergiant Antares, on the 7th. By month's end, Mars is east of the right knee of Ophiuchus, the Giant.
Jupiter rises with Virgo after midnight at the beginning of January and appears in the east at 11 PM EST by the end of the month. It is the brightest object in the southern sky before dawn throughout January.
Saturn reaches opposition in Gemini at 6:00 PM EST on January 13th, so it should appear at its best near midnight, long after the final glow of dusk disappears in the evening. The last opposition was in December of 2003 when Saturn was approaching its July, 2003 perihelion (closest distance to the Sun.) The planet is now 6 months beyond perihelion and will move farther from the Sun until it reaches aphelion in 2018, so the current opposition should provide views of Saturn which will not be surpassed until it next arrives at perihelion nearly 30 years from now. Saturn's rings are currently tilted away from Earth so we have an excellent view of its southern hemisphere. During the first part of 2005, Saturn will appear to play tag with the bright stars of Gemini, Castor and Pollux.
When outer planets are near their oppositions and can be found on the opposite side of Earth from the Sun, the Earth passes these slower outer planets as they circuit the Sun. During the weeks required for the passage, the planets appear to first move to the east, then to the west, and then resume eastward motion. This apparent reversal of movement is referred to as "retrograde motion."
It gave fits to the early Greeks as they attempted to predict planetary motion and caused them to propose that planets moved in circles whose centers, in turn, moved around the Earth like small gears moving around the perimeter of a large gear. They called the small circles "epicycles" and whenever their models failed to accurately predict planetary position, they simply added additional epicycles to the epicycles in their model to match the model to the new observations. Ultimately, the geocentric (earth-centered) model became too cumbersome and the door was opened for the sun-centered model of Copernicus.
Uranus in Aquarius, and Neptune in Capricornus set soon after the Sun and are trapped in the glow of dusk in January.
Quadrantid Meteor Shower
The peak of the Quadrantid Shower will be right before sunrise on January 3rd, possibly approaching 1 to 2 meteors every minute for locations with dark skies. Unfortunately, the waning quarter moon interferes with the Quadrantids this month, so the best views will be before the Moon rises. Check the north-northeastern skies during the latter part of the evening of the 2nd. The point in the sky from which the meteors appear to emanate (radiant) is in Quadran Muralis, the abandoned constellation formerly located between the head of Draco, Arcturus, and the handle of the Big Dipper.
The near-Earth Asteroid, 2003 EH, appears to have an orbit which matches that of the debris associated with this shower and may be the remnant of the broken up comet that produced this debris.
January Moon
The Full Moon of January is in Cancer on the 25th at 5:32 AM EST. It is called the "Moon after Yule" or the "Old Moon." Colonial Americans referred to it as the "Winter Moon," and to the Anishnaabe (Chippewa and Ojibwe,) it is known as Gitchi-manidoo-giizis (Great Spirit Moon.)
On January 3rd, the last quarter Moon is 0.4° south of Jupiter at 9 PM EST. The waning crescent Moon is within 3° of Mars at 2 PM EST on the 7th and passes 5° south of Mercury at 9 PM EST on the 8th. On the same evening at 10 PM EST, it is less than 5° from Venus. On the 13th, Uranus and a tiny waxing crescent Moon are separated by 4° at 3 AM EST. At the end of the month, the waxing gibbous Moon moves by Saturn at 3 AM EST on the 24th and the waning gibbous Moon passes within 5° of Jupiter at 6 AM EST on the 31st.
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