28 Jun 2008
Imagine getting up one fine June morning in the middle of a forested wilderness, taking a deep breath, letting out a long sigh, and enjoying the beautiful morning sky. Then suddenly the sky splits in two with a bright flash, only to turn into a blinding fireball so hot you feel you might burst into flames. Thunderous booming sounds overcome your pleasant surrounds and shake the earth. Your quiet, noneventful world has literally been rocked.
That would be an eye-opener, eh?
That's what happened 100 years ago on the 30th of June, 1908, over a remote area in Russia's Siberia, specifically near the Podkamennaya Tunguska River. It is an area so remote that few people lived there then, probably fewer on the outside even knew of it.
The Tunguska Event, as it is understatedly known in the scientific community, was real, to be sure. But a real what?
Understand that at the time, in the early 1900's, there were no satellites, phones, worldwide tracking stations, email, texts, and the like. If some monstrous event took place in the middle of Siberia back then, the news would travel slowly, and any response in getting to this forsaken place would be slower.
In fact, it wasn't until the 1920's that a Russian scientist, Leonid Kulik, curious about local accounts of a Brobdingnagian explosion that happened decades before, made some expeditions there.
Although he deduced that the explosion was from a meteorite impact, his findings - and the findings of all the subsequent expeditions there - discovered hundreds of square miles of felled and scorched trees. But there was no impact crater in the middle of the mayhem!
What on earth was this Tunguska Event, a phenomenon that knocked over more than 50 million trees and exploded with a force 1000 times greater than the Hiroshima atomic bomb, but left no crater?
Believe it or not, the jury is still out on this one. The prime suspects are extraterrestrial, as expected. But as to whether it was a comet or asteroid...? Go there and expect a fine argument.
A small comet is suspect because it is so weakly put together that it would be expected to blow to smithereens when impacting our dense atmosphere, unleashing a truckload of energy but leaving in essence nothing but dust and water vapor.
But a comet just tens of meters across would have ripped apart higher in the atmosphere, and the trace chemical evidence found on the ground imply an asteroid, not a comet.
Exactly one hundred years later there is still no consensus as to what it was. But there is plenty of agreement on what these intruders - asteroids or comets - can do when they hit.
The Tunguska beast was just a small impactor traveling at just tens of kilometers per second that fell over an unpopulated area full of nothing but trees and bunnies.
If the Tunguska rock had struck just hours later, Europe would have been in deep do-do.
A blast like that could easily have leveled a populated city like St Petersburg or London and all its inhabitants. Bigger rocks, on the order of hundreds of meters across or even a kilometer or two, can spell doom to entire continents of life.
We should be thankful that although blasts like Tunguska happen about once every several centuries or so, that most of our planet is still pretty much uninhabited. Nevertheless, a pinpoint strike can kill - big time. Just a little heads up!
Until next time, clear - and safe - skies!
15 Jun 2008
At last, summer. Not that many of us are looking forward to the hot weather, the most likely higher gas prices, and the escalating political rhetoric.
Many of us look forward to the nighttime skies above our heads, and all the glories of the summer heavens.
Sadly, the summer skies come late and leave early. Our tilt, now fully towards the sun, means that it will not get dark until after nine, a late start for many.
But the summer skies are worth it. Let's look a little closer at some things you may want to try and see.
The most obvious summer addition is the summer Milky Way. It's a beauty. Of course how much it inspires pretty much depends on dark skies, a phenomenon going the way of cheap oil. The Milky Way is visible sometime during the night all year long, but what makes the Summer version so pretty is that we are now facing the civic center of our galaxy.
In that direction stars are more concentrated, there are more nebulae and clusters, and there is our dense center. The diamonds-over-the-head view, the one that extends from south to north, doesn't really kick in at reasonable hours until later in the summer. But if you stay up until after midnight, you can see it now.
If you haven't yet, why not try and make this the summer you see nebulae and star clusters. Nebulae are huge luminous gas clouds where stars are being created. Clusters, open are globular, are exactly what they say - clusters of star, sometimes hundreds of thousands strong. There are many located in the southern skies, near the center of the Milky Way.
Alas, Saturn is in its last weeks of visibility, but Jupiter always puts on a fine show. It won't be until July that Jupiter makes a reasonable, pre-midnight showing. But it is worth getting out an old scope to take a look at the big guy, with his striped atmosphere, great red spot, and Galilean Satellites.
You will notice that since we are tipped so much toward the sun, that we end up being tipped away from our nighttime neighbors. So the planets and the Moon won't exactly be hovering over our heads where they are best seen. That's part of the compromise observers make all the time.
In August, specifically around the 12th, we will get our annual Perseid meteor shower. The Moon may mess things up a bit until the predawn hours when it goes below horizon, and which is the best time to see these critters anyways. This year the west coast seems favored to get the best show so it may be worth waking up early to go see these fireballs.
There are all kinds of wonderful things to explore in the summer skies, and the fact that the weather is usually nice here in Southern California helps a lot. I would suggest getting a recent copy of Sky & telescope or Astronomy magazines if you are seriously considering checking out the skies. They have detailed and easy-to-read sky charts in there for nailing down those clusters and clouds and planets. It would be a fine season maybe just to spend the time relaxing and try to "de-stress" by getting a map, some binoculars, a lounge chair - and just looking up. The effects are amazing.
01 Jun 2008
The Mars Phoenix Lander finally made it. After years and years of planning and testing and engineering and innovation - and the most nail-biting 7 minutes in recent JPL history as it touched down - we have a robotic lander near the north pole of Mars.
It really is an amazing feat getting that little guy to a target 100 million miles away and safely landing it. But now I fear I risk sounding like the Grinch Who Stole Christmas. Why?
For those of us who read, eat, and drink space, we have listened to plenty of people over the years who spend their waking lives looking for life outside our planet. A noble cause to be sure, but if one listens to what is being said - I mean truly listens with slightly skeptical ears - there are some things being said which beg further examination and which tie into our latest Martian encounter.
Invariably a comment is made that goes something like this: To find life, follow the water. True, any kind of life, even the most simple, with its endless complexities, demands the universal solvent we call water. It is an amazing molecule worthy of several articles devoted entirely to its awe-inspiring characteristics.
So to look for water in the universe in hopes of finding life is sensible. Where we venture into nonsense is to make the implication that where water is there must also be life. As if water plus rock guarantees life. "Well, it happened here, so it must have happened elsewhere." Oh, must it have? Well, out comes my skeptical Scroogie science self who then asks, Why "must" life pop from nonlife with nothing else but rocks, water, and time?
Maybe we have heard the "If there's water there's probably life!" mantra so much over the years that we have become numb to it and don't critically think about it. But, as one trained in the sciences to eye all things with a healthy skepticism, I might ask: If life pops up so easily, how does it do so? If it is so ubiquitous, why can't we make it pop up in the lab? Why should we expect blind, random, mindless nature to "just do it" all over the universe?
Which often brings up the inevitable theological statement: If God is the source of life then He can put life wherever He wants! That is absolutely true. But my questions are directed to those who claim no invisible means of support, to those who claim that nature is all there ever has been, all there is, and all there ever will be, to paraphrase the late Carl Sagan.
The Phoenix, a remarkable little lab in its own right, may find signs of ancient water. That would provide us with marvelous insight into the history of our solar system. It would afford more evidence that either supports or breaks down countless hypotheses floating about concerning Mar's past. That in itself is a great stride for planetary science, and to that my hat is off.
But allow me a humble prediction concerning Phoenix. Everywhere we look in the universe - I mean everywhere - we pick up more and more evidence every year that we are one of a kind, this planet of ours. Earthlike planets are not a dime a dozen as once thought. Our makeup is extraordinarily and exquisitely perfect for life. I believe that Phoenix will not make a case for ancient life on Mars. On the contrary, I believe it will provide even more evidence that our planet is even more extraordinary than we now believe it is.
Might I be wrong? Of course! That is part of the beautiful discipline of science. But part of science also involves evidence and models, two things sorely lacking in the "life must be everywhere" scenario.
I hope all this starts some good discussion. Are we unique or is life everywhere, including Mars? Is there life because of a long random set of mindless events, or did Someone put it here? Why is there Life at all?
Maybe like its mythical namesake, the Phoenix spacecraft will bring to life from the ashes the Big Questions that we seem to have forgotten to ask anymore in our busy, busy lives.
Until next time, clear skies - and clear thinking.