Oumuamua

Oumuamua is an asteroid which came from beyond the solar system.  Perhaps it was ejected from a star system in the Carina–Columba association (which is not an Italian fraternal organization but rather a vast nebula by Eta Carinae about 100 parsecs) around 50 to 100 million years ago, but its age and point of origin are unknown.   It is whipping past the sun and then back into the vast darkness between the stars at a prodigious velocity (apparently it was traveling through interstellar space at something like 26 kilometers per second (58,000 miles per hour).  The object, which measures between 100 and 800 meters (300 to 2500 feet), was initially classified as a comet, but its speed, its orbital eccentricity, and its bizarre shape–which is like an icicle or a shard–caused astronomers to realize it was deeply strange interloper from beyond.

The object has been closely observed by many of the Earth’s great observatories and it is apparently a dark red—which is caused by cosmic radiation striking it for 100s of millions of years (Kuiper belt objects have similar coloration).  It is traveling far too fast for any existing human craft too reach (although we may be able to build such crafts in the near future), however scientists are assessing it for traces of life or civilization by means of radio telescopy.  It will be out by Jupiter next year and far beyond are kin soon after that, but scientists have learned a great deal from the visit.  Additionally they speculate that other such objects come through the solar system at the rate of one or two per year (which does not seem like a lot considering how large the solar system is).  We are lucky to have spotted this shard, but its catastrophic shape makes one speculate that there is a lot about planetary formation (and destruction) which we don’t know yet.

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The Shield of Jupiter

Ferrebeekeeper has already posted about the aegis, the invulnerable shield of Jupiter/Zeus, which was fashioned by the king of the gods from the skin of his foster mother (and loaned to his favorite daughter.  However the concept of Jupiter’s shield has a larger significance.

Yesterday morning, an unknown object appears to have slammed into the planet Jupiter.  Oregon based astronomer Dan Petersen was watching the gas giant at 4:35 AM PST (September 10^th, 2012) when a bright flash erupted from near the Jovian equator.  Another amateur astronomer, George Hall of Dallas, TX was filming the planet through his 12 inch telescope and recorded the flash (you can see the video here).

The September 10th, 2012 Flash on Jupiter (recorded by George Hall)

Thanks to the florid nature of science fiction entertainment, it is easy to imagine scaly green Guarillions testing out energy weapons against the huge planet, but the flash was almost certainly from a comet or asteroid striking the surface (we will know more as astronomers look at Jupiter this week).  Such impacts have proven to be much more common than imagined.

Jupiter has a mass of approximately 1.9 x 10²⁷ kg (which is equivalent to 318 Earths).  The gas giant is 2.5 times more massive than all of the rest of the non-sun objects in the solar system added together. The sun itself comprises between 99.8% and 99.9% of the mass of the system (which should put some perspective on the precision required for our ongoing programs to scan the nearby galaxy for exoplanets).

Jupiter Relative to the Sun and the Earth (NASA Goddard Space Flight Center)

The huge mass of Jupiter (relative to other planets and moons) means that a great many asteroids, comets, meteors, and whatnot fall into its gravity well.  Were it not for Jupiter, these hazardous leftovers would otherwise fly all around the solar system willy-nilly knocking holes in things and creating unsafe conditions (just ask the poor dinosaurs about this).  The ancient myths of the Aegis provide a powerful metaphor for this protection. Jupiter does indeed provide a shield for the smaller planets:  If it did not suck up so many cosmic punches, who knows if life could even have survived?

(Lithograph by F. Heppenheimer)

Giant Lightning Storm on Saturn

The surface area of Earth is about 510 million square kilometers.  That number adds some perspective to the giant storm which has been raging on Saturn since December and now covers approximately 4 billion square kilometers of the gas giant planet.

The Storm Raging on Saturn (photo from the Cassini probe, NASA)

Saturn’s atmosphere is usually calm and tranquil–although powerful storms have been observed by telescope in the past. Now however Saturn is being closely observed by NASA’s Cassini space probe which is in orbit around the planet and we have some precise details.  At the storm’s height, Cassini detected over 10 lightning strikes per second.  Additionally, these lightning bursts can emit 10,000 times the amount of electrical energy as a typical lightning burst on Earth.  Saturnian meteorologists (or whatever weather scientists for the great ringed planet are called) speculate that this super lightning is so powerful because of the juxtaposition of layers of water ice with layers of crystallized ammonia.

A Detailed False Color Picture of the Storm (NASA)

Saturn’s weather is known to fluctuate with the change of the season on the frigid planet and the huge rings are presumed to affect the weather in unknown and unpredictable ways. The current giant storm is taking place in the northern hemisphere of Saturn, which is entering spring.

Although Saturn’s storms are not as well-known as the Great Red Spot on Jupiter, the planet’s north pole does feature a hexagonal storm which has persisted for at least 25 years.  Named for Jupiter/Zeus’ father (who was known as Cronus to the Greeks), the planet Saturn is the second largest in the solar system with a surface area of 4.27 x 1010 square km.  The planet is orbited not only by its famous rings but also by at least 62 known moons including Titan, the only known satellite with a dense atmosphere, and Mimas, which features the largest known impact crater.