If you could drive straight down, into a tunnel bored through the crust of the planet, you'd hit this molten mess in about an hour. It's called the asthenosphere - a sluggish sea, several hundred miles thick, on which floats the Earth's cool epidermis - the so-called tectonic plates.
Of course there is still unexplored terrestrial territory, but most of it is waterlogged. Submersed secret places, such as the Challenger Deep, which today lure hi-tech adventurers like Richard Branson and James Cameron, will undoubtedly provide welcome fodder for 'National Geographic.'
Each year, thousands of UFOs are sighted and reported, which is an impressive tally of unidentified aerial phenomena. Surveys show that roughly one-third of the populace believes that at least some of this sky show is due to extraterrestrial spacecraft, here to probe our airspace and, when that proves boring, our bodies.
It's hard to imagine anything more interesting than learning how we're woven into the enormous tapestry of existence. Where did our universe come from? How special is our world, and how special are we? We allocate tens of billions of dollars annually to NASA, NSF and academia in search of the answers.
Today's voguish threats, including climate change, population growth, massive war, and resource depletion, are all amenable to a fix if we act prudently. And even if we don't, these problems are incapable of obliterating all of humanity, let alone destroying the Earth. No, the real End of Days will happen slowly, as the Sun ages.
It's worth noting that invoking God as the entity who set our universe in motion isn't contradicted by the data. Of course, scientists would say the supreme being hypothesis is faith, and outside the realm of science - that it's not amenable to experiment. But we currently have the same problem with the notion of parallel universes.
When I graduated high school, nearly a half-million people subscribed to 'Popular Electronics' magazine. Soldering up some radio or hi-fi amplifier on the basement workbench was not just a personal passion - a lot of young people were doing the same. The magazine expired in 1999 for lack of interest.
A century ago, scientists believed there was only one obvious stomping ground for alien biology in our solar system: Mars. Because it was reminiscent of Earth, Mars was assumed to be chock-a-block with animate beings, and its putative inhabitants got a lot of column inches and screen time.
About the only things that are unique to Earth are our biota and our culture. If aliens ever come here, they'd most likely be either biologists or music fans. Neither one has much reason to antagonize our armed forces.
The strongest signals leaking off our planet are radar transmissions, not television or radio. The most powerful radars, such as the one mounted on the Arecibo telescope (used to study the ionosphere and map asteroids) could be detected with a similarly sized antenna at a distance of nearly 1,000 light-years.
If this is the only planet on which not only life, but intelligent life, has arisen, that would be very unusual.
Consider: Life arose on Earth close to four billion years ago. Four billion years of slithering, swimming, and soaring life forms. But only in the last 200 thousand years has a species arisen that can fathom the laws of nature and build hardware able to signal its presence.
Consider that the overwhelming majority of those 40,000 near-Earth asteroids are small enough to fit on the parking lot at the mall. And while these rocky runts won't cause Armageddon, they could still flatten such popular hominid hangouts as Manhattan or downtown Des Moines.
Forecasting Armageddon has become trendy of late, with a great deal of attention being given to an interpretation of the Mayan Calendar suggesting that Mother Earth is destined for doom in December of 2012.
The usual metric for whether a planet is habitable or not is to ascertain whether liquid water could exist on its surface. Most worlds will either be too cold, too hot or of a type (like Jupiter) that may have no solid surface and be swaddled in noxious gases.
I've often fantasized about visiting the Bahamian beach where Columbus first stumbled ashore in 1492. Sadly, no one knows where that beach is. In fact, no one's even sure which island Columbus first encountered (there are three candidates). It's a pity, a disappointment, and a lost revenue source for the Bahamians.
Note to academics: Aristarchus' track record of astronomical research would probably have guaranteed him tenure somewhere, if tenure had been invented. His stack of reprints included measuring the distances of the Moon and Sun.
I got interested in astronomy at the age of 8 because I was looking at an atlas of the planets in my parents' apartment in Arlington, where I grew up. I got a telescope at age 10, which is pretty normal, and by the time I was in eighth grade, I had already seen a lot of cheesy sci-fi films.
Ever since the infamous quiz show scandals of the 1950s, the feds had insisted that TV game shows be honest - or that at least they didn't cheat. So as a 'Dating Game' bachelor, I didn't know what I was going to be asked. The other bachelors and I were required to concoct our answers in real time.
While I have always thought that the motivation for looking for E.T. was both self-evident and patently worthy, it's possible that I'm a victim of my own job description. Others don't inevitably agree. Some will opine that there are better ways to spend the money.