Tuesday, May 3, 2016

Looking up

Recent posts here have focused upon my own writing (including one post about this blog itself). It's time to look up from my keyboard! Way up. Hence this news-in-astronomy post ...

 You know how "when lightning strikes" is a metaphor for the highly unlikely? It turns out that the odds aren't that long. According to National Geographic:

The odds of becoming a lightning victim in the U.S. in any one year is 1 in 700,000. The odds of being struck in your lifetime is 1 in 3,000.

Lightning strikes aren't a lottery, of course. During thunderstorms you can influence the odds by (for example) standing next to -- or better, not -- tall conductive objects.

Heads up!
Meteorite strikes are something else. You can't avoid them (though maybe someone ought to be working on that) and they are far less likely than lightning strikes. Do meteorite deaths even happen (to anyone but dinosaurs)? Maybe. National Geographic reports your risk of being killed by a space rock at 1 in 75,000 or, in another study 1 in 700,000. See "Scientists investigate suspected meteorite death in southern India."

And a bit farther afield? A space rock that hopefully won't fall upon our heads? Well, there's the Moon, which (a recent study indicates) may not be quite as stable as we thought. As in: the movement of subsurface lunar magma may once have altered the Moon's axial tilt by six degrees! See "Icy spots on our moon: Evidence that its axis has tilted."

On comet (on Cupid ...?)
And then there are comets. By standard usage, a comet most notably differs from an asteroid in that the former grows a tail (i.e., a sunlit stream of vapor sublimated from ice or other volatile liquid) in the part of the object's orbit that brings it near the Sun. A comet's other distinguishing characteristic is a highly elongated orbit about the Sun.

What should one call an object with a comet-like, highly elongated, Sun-approaching orbit that doesn't show/grow a tail? By analogy to a breed of tailless cats (hat tip to my buddy, Charlie), a Manx comet. And just such an object, dubbed C/2014 S3, has recently been spotted. Theory has it such objects formed (like Earth) in the inner Solar System and then (unlike Earth) got thrown -- by gravitational interaction with a much larger object(s): a planet(s) -- into a much changed orbit. The hunt is on for more celestial objects like C/2014 S3. A statistical study of such objects, if they exist and can be found, may instruct us on the dynamics of the early Solar System. A physical examination of a Manx comet should reveal the nature of Earth's actual building blocks. See "Astronomers find a tailless comet, first of its kind."

In the outer darkness of the Solar System, among the Trans Neptunian Objects, aka deep in the Kuiper Belt, an unidentified planet may lurk. The presence of a remote planet is hinted at by several less-than-planet-sized Kuiper Belt Objects in similarly anomalous orbits. If the suspected planet exists, it won't be a pipsqueak world like Pluto (smaller and less massive than the Moon), but rather it'll have several times the mass of Earth! See "New evidence suggests a ninth planet lurking at the edge of the solar system."

Next time (barring a meteorite falling upon my head), astronomical news from beyond the Solar System.

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