Tuesday, September 25, 2018

Of the universe

Today's post is a roundup of recent astronomy news.

First, and closest to home, a look at a neighbor: "Ice Confirmed at the Moon's Poles." Such ice has long been suspected, of course, and indirect evidence of it gleaned -- but this is the most definitive proof yet. Water on the Moon is seriously important to any hopes for a permanent lunar presence.

Lucy (in a few years)
If I may then look ahead to upcoming discoveries, consider "NASA’s Lucy in the sky with Trojans." "Lucy" in this context is a probe to be launched in 2021 to explore (mainly) Jupiter's Trojan asteroids. These asteroids co-orbit with Jupiter, one bunch 60 degrees ahead of the planet, the other 60 degrees behind. (They're called "Trojan" because the first few of these rocks were named for heroes of the mythic war.) And they're darned varied and interesting ...

Next, a tidbit from the collision, in 1607, of two stars to cause a nova. From astronomers sifting the distant debris we have "Radioactive Molecule Found in Stellar Merger Remnant."

When neutron stars collide
String theory, the leading hope for reconciling quantum mechanics and general relativity, requires (depending on your specific choice of a string theory -- there are many) 10 or 11 dimensions. So how is it we experience only four dimensions? (The fourth is, glossing over some subtleties, time.) In a nutshell, the extra dimensions are supposedly compactified -- in come sense curled up, too small for us to notice -- but gravity "leaks" into them anyway. Or not: See "Gravitational waves provide dose of reality about extra dimensions." This new study concludes there's no evidence of such gravitational leakage over 100 million light-years (to an observed neutron-star collision).

Our last topic of the day is also cosmic. You may recall the "explanation" for the universe's apparent accelerating expansion is "dark energy" -- which is a label for our ignorance, and not an explanation at all. Efforts to characterize dark energy have, so far, all failed. If you have 15 or so minutes, I'll recommend this overview of the controversy, from Cosmos: "Is the search for dark energy a dead end?"

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