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Here is a particularly fascinating historical object: an original Roman semi-cylindrical legionary shield (scutum) from Dura-Europos (a very strange Roman border city which requires its own post). Although pieces of other ancient Roman shields have been found, this is by far the finest and most complete example. Yet even this stunning shield has some deficiencies–it was found in thirteen flattened pieces which had to be reassembled, and it is missing its iron boss (a hardened round dome in the center used for ramming and for deflecting swords, spears, cavalry lances, and javelins).
Even if the most important piece is gone, this shield demonstrates the construction of such protective devices. These large curved shields were made of steam curved layers of wood annealed together on top of each other in cross-grained patterns to be light yet resistant to the sharpest and hardest stabbing weapons. The edges were lined with metal to strengthen the against hacking attacks or shattering. Plus, in lieu of a boss (of which we have other examples) this shield still has the original legionary artwork in extremely fine condition. Shields were painted with different emblems so that men could swiftly recognize their units in the chaos of battle, however these designs always reflected the Roman iconography of victory. This example features an eagle with a laurel wreath, winged Victories, and a lion. Gorgons, bulls, boars, winged horses, and above all Zeus’ lightning bolts seem to have also been popular.
Probably a military historian would write at length about Roman armor, swords, ironwork, fortresses, roads, organization, ballistae, and goodness knows what else. Yet, to my eyes, this is the definitive piece of Roman military hardware. In order to be useful, a shield of this sort requires endless drilling with lots of other soldiers with the same sort of shield. Imagine going into a battle in the Roman-age world. There would be direct visceral carnage everywhere. Your opponents have war chariots, huge axes, enormous pikes and goodness knows what else and you would have…a curved piece of plywood and a very long iron knife? And yet with training, nerve, and discipline, each shield became an impervious scale of a giant armored monster made of men.
Roosters are well known for being vain, arrogant, aggressive, greedy, and loud. They are also famous for being brave and for leading their flocks. Those are also the universally acknowledged traits of noblemen–so it is unsurprising that the rooster/cock is a popular device on shields, coats of arms, and heraldic standards. Ancient vases indicate that the rooster was a device of nobles and warriors at least as far back as the classical Greek age. Here is a little gallery of rooster heraldry both historical and fantastical which I found on line (actually I slipped a few hens in to the mix to make it more fun). Enjoy the escutcheons and the poultry!
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 10th, 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).
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).
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?
Yesterday NASA’s spacecraft MESSENGER entered orbit around Mercury, the least explored of the Solar system’s rocky inner planets. This is the first time a spacecraft has been in orbit around Mercury and it represents a tremendous engineering achievement. Since gravity becomes more intense the closer one comes to the sun, Messenger had to slingshot back and forth among the inner planets for some time in order to accomplish the tricky feat. The spacecraft had to undertake a 4.9 billion mile (about 7.9-billion kilometer) journey to enter orbit around the closest planet to the sun. Of course that hefty mileage only is equal to 0.00083 light years!
Having survived the grueling trip, the spaceship must now carry out its mission in the blistering bath of solar radiation. To survive next to the star, Messenger is equipped with a large sun visor which prevents the little craft from frying like a quail egg.
Messenger will try to determine the planet’s mineralogical composition and learn about its geological history (the surface of Mercury is reckoned to be one of the oldest in the solar system). The robot probe will fully map Mercury and analyze the planet’s composition. Like Earth (but unlike Mars and Venus) Mercury has an internal magnetic field. Additionally, the tiny world is incredibly dense. In order to learn more about the planet’s core Messenger will measure the extent to which the planet wobbles on its rotational axis. Studying the partially molten interior of Mercury should provide clues about how the planet formed which will help us better understand the creation of all planets (especially in conjunction with the flood of data regarding exoplanets which we are beginning to receive).
Since the craft will be trying to learn the secrets of Mercury’s molten interior, it is worth reflecting on the deity whom the planet is named after. Although he was worshipped as a messenger, a herald, and a god of commerce, the Greco Roman god Hermes/Mercury was also quietly worshipped as a god of the underworld. The Greeks and Romans regarded him as a psychopomp who guided souls down to Hades with his magical staff. Because (like the somewhat similar African traveling god Eshu) Hermes was able to go anywhere at will he was one of the only entities in the Greco Roman pantheon free to enter and leave the underworld.
Although we are not capable like Mercury of going everywhere at our whim, I think it is a tremendous accomplishment to navigate a robot spacecraft into broiling orbit around the innermost planet. That we are using the craft to learn the secrets of the fiery underworld of the swift planet seems like a fitting tribute to the god who was slayer of Argus, giver of charms, messenger, schemer, luck bringer, and patron of travelers and wayfarers (even those voyaging to their last end or to places the ancients could never dream of).