August 27, 2009 | David F. Coppedge

What’s Up With the Planets?

Here are planets and moons making news in our celestial neighborhood, the solar system.  Maybe we’ll drop in on another neighborhood while we’re looking around.

  1. Venus resurfacing:  Planetary geologists can’t get away from the evidence that Venus underwent a planet-wide volcanic resurfacing epoch.  Crater counts and lava flow surveys leave little room for doubt that, however and whenever it happened, a new coat of lava spilled over the entire globe over a short time.  It was a catastrophic, not a uniformitarian, process.  That conclusion was reported in Icarus.1  (See “Earth’s ugly sister can’t get a date,” 08/16/2004.)
  2. Earth climate:  Work at the National Center for Atmospheric Research shows how the 11-year solar cycle influences climate on decadal scales; this was reported by Live Science and PhysOrg.  But do orbital cycles cause long-term shifts, like ice ages?  That was discussed in Science magazine this week.2  Peter Huybers of Harvard explained that the interpretation of ice cores is fraught with problems.  “Coming up with orbital scenarios that look like the Antarctic record is too easy,” he lamented after examining competing models.  “If we are to use Antarctica’s orbital beat to better understand the orchestration of global changes in glaciation, we must first decipher which elements of the climate system are in play and how their responses get recorded in Antarctica’s ice.”  He put the answers in future tense.
  3. Mars floods:  Remember that big canyon on Mars that would stretch across the United States if on earth?  Maybe someone pulled a plug.  Yahoo News reported on a new theory: for at least one section, hot briny underground water caused a collapse, then the water gushed out.  They don’t know where the briny water went, and they can’t say when or how long ago this happened, but it seems catastrophic, not uniformitarian.  Regarding the entire Valles Marinaris, the University of Washington theorizers ignored Ockham’s Razor and said, “it’s likely that the whole system formed from a ‘mixed bag’ of mechanisms, including floods, drainage and tectonic forces.”
  4. Saturn dune moon:  What builds the 300′ high sand dunes on Titan?  A new theory reported by Science Daily builds them out of sticky particles without oscillating winds.  The hypothesis by Rubin and Hesp leads to a sticky problem, though: if correct, “new hypotheses regarding the composition, origin, evolution, grain size, stickiness, quantity, global transport patterns and suitability for wind transport of Titan’s sediment; the velocities, directions and seasonal patterns of Titan’s winds; and overall surface wetness will all have to be completely reassessed.”
  5. Saturn geyser moon:  Here’s a PDF file of a Powerpoint presentation by Cassini scientists on the latest thinking about Enceladus, the geyser moon of Saturn.  They think the evidence points to liquid water underground, but another team publishing in Icarus this month thinks otherwise.3   
  6. Neptune anniversary:  Voyager 2’s spectacular encounter with Neptune’s large moon Triton was 20 years ago this month.  In celebration, NASA-JPL issued a set of newly-enhanced photos of the moon’s surface taken in 1989.  The oblique views and a video flyover were produced by Dr. Paul Schenk, who has perfected the stereo imaging technique and is producing flyovers of other bodies based on archive images.
        In 1989, astronomers were stunned to see Triton, one of the coldest bodies in the solar system, sporting active geysers and evidence of recent cryovolcanism.  The moon looked young: “Voyager mapped only the hemisphere that faces Neptune, but revealed a very young surface scarred by rising blobs of ice (diapirs), faults, and volcanic pits and lava flows composed of water and other ices.”

Let’s wrap up with a story of a planet outside our own solar system – an extrasolar planet that shouldn’t exist, but does.  Nature reported a “hot Jupiter” orbiting a star in less than one earth day.4  Scientists couldn’t believe their eyes.  Tidal forces should have made this planet spiral into its star in less than a million years, but the star is thought to be a billion years old.  It seemed impossible we could be seeing a planet in the last wink of its lifetime now.  Ask Science Daily.  Even more confusing is the fact that the planet is going the wrong way around the star.  This story made Science Daily twice.

1.  Romeo and Turcotte, “The frequency-area distribution of volcanic units on Venus: Implications for planetary resurfacing,” Icarus, Volume 203, Issue 1, September 2009, Pages 13-19, doi:10.1016/j.icarus.2009.03.036.
2.  Peter Huybers, “Antarctica’s orbital beat,” Science, 28 August 2009: Vol. 325. no. 5944, pp. 1085-1086, DOI: 10.1126/science.1176186.
3.  Kieffer, McFarquhar and Wohletz, “A redetermination of the ice/vapor ratio of Enceladus� plumes: Implications for sublimation and the lack of a liquid water reservoir,” Icarus, Volume 203, Issue 1, September 2009, Pages 238-241, doi:10.1016/j.icarus.2009.05.011.
4.  Hellier et al, “An orbital period of 0.94 days for the hot-Jupiter planet WASP-18b,” Nature 460, 1098-1100 (27 August 2009) | doi:10.1038/nature08245.

The history of astronomy and planetary science is a history of surprises and anomalies.  Scientists build world views of how things should be, and how old they must be, and the real worlds keep astonishing them.  Some people won’t learn humility any other way.

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Categories: Physics, Solar System

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