29 Jan 2005
One of the most disappointing times for a newbie backyard astronomer comes when he or she looks for the first time through a brand new telescope and sees pretty much nothing. Well, nothing like what one sees on the covers of Sky and Telescope or Astronomy magazine or on websites like Astronomy Picture of the Day.
All those amazing images that have been pouring into the public mainstream for decades - grand and colorful spiral galaxies, kaleidoscopic nebulae, far-flung remnants of supernovae - are seemingly nowhere to be found.
Why is that, though? Why is it that when one looks, for example, in the astronomy journals at images of our sister galaxy, Andromeda, that the rich detailed blue spiral arms and central yellow fireworks come to life, but using our own eyes through even a good amateur telescope we see nothing much more than a grayish-green faint celestial fuzzball?
It’s a question of design and engineering.
Our eyes have been designed for life on a sunny planet. They are amazing works of art, able to capture photons of energy and translate them into electrical messages for the brain where those messages are turned into images.
But our eyeballs are inefficient in the best way. They are actually able to capture and process less than one in a thousand photons that make it in. Which is great, if you think about it.
If our eyes could suddenly process more photons, like one of a hundred or one of ten, all around us would seem intensely bright. We’d need some sort of filters to reduce the photon count.
Not capturing a lot of photons is not the only “problem.” Our eyes also don’t store photons to make the images we see.
Say some lucky photons enter the eye and react with the chemicals in the retina, the layer at the back of our eyes. These chemicals send their message to the brain but then “reset” for the next photon strikes.
This resetting allows continuous and successive images to be made and translated quickly so we can get constant and accurate updates from the outside world. Without this chemical process the entire world would seem more of a blur than it is already.
Try staring at something for a minute. Then close your eyes and see the image still there quickly fading away. Those chemicals are resetting; the image is soon gone.
Those beautiful space images we see are processed differently. Nowadays nearly all telescopes have charged couple devices (CCD) hooked up to them that act sort of like an artificial retina for astronomers. But these “retinas” work a little differently than human retinas.
First, they can capture and use more than half the photons that strike them! That is great efficiency.
Moreover, in CCDs the energy from the incoming photons can be stored. Heavenly objects appear very dim and fuzzy to our eyes because we can’t get enough photons to make a discernible image. But in one of these fancy cameras the energy from photons can build up over time until an image can finally be seen.
Some of the great images we have now are a result of minutes to hours of exposure to a single heavenly object. Some of the Hubble images of the faintest, most distant galaxies out there required over 30 hours of exposure! We’d never see those staring through a telescope ourselves.
And of course the images nowadays can be digitally manipulated to bring out colors and different textures and hues, things we are unable to do with our eyes.
On top of that some telescopes can “see” in wavelengths we cannot, such as infrared, ultraviolet, and X-ray.
Modern technology has allowed us to see incredible wonders of the skies in breathless detail, to be sure. But it doesn’t beat a walk out on a clear moonless night where most of us can - with our very own eyes - observe and absorb the awesome glories of the starry heavens.
15 Jan 2005
How can some scientists dare to declare planet Earth a near perfect, paradisiacal place for life when events such as last month's earthquake and tsunami kill hundreds of thousands and leave millions orphaned or widowed or homeless? Surely this epic event is clear evidence to us all that there is plenty to be questioned regarding this home of ours. Someone messed up somewhere.
It isn’t easy to try and portray this planet as a perfect home while watching the horrible images of bodies including women and children washing up on beaches in Sri Lanka, or entire communities in Sumatra just recently buzzing with life now completely swept off the map.
But things could be worse – a lot worse. And things could be better – a lot better - if we all get our act together.
This planet of ours has this extremely unique make-up. We have an oversized, hot, molten center enveloped by an extra-thin crust. Both of these are amazingly well composed for life on this third planet out from the sun. Their co-existence means that life can thrive here, but with some risk.
The best and latest theory elucidating how our planet got to be the way it is involves an amazing collision over 4.5 billion years ago.
It was then, we believe, that a Mars-sized object struck a very young and then smaller Earth with a glancing but devastating and well-timed blow. In fact, had the colliding body passed through an hour sooner or later only an uneventful near-miss would have occurred. But the collision happened, and it was magnificent.
It cleared away a horribly thick and deadly atmosphere, shredded away most of our crust much of which went into the formation of our Moon, and added an extra heaping helping of hot radioactive core material into the newly rearranged Earth.
How can a thinner crust and hotter inner parts help form a planet fit for life? Allow me a short order explanation of plate tectonics.
Our now thin crust resides, but certainly does not rest, upon a layer of molten, thick material below. How thin is it? Imagine an apple cut in half. The skin on the apple is about how thick our crust is compared to rest of the planet. It is very thin.
Being this thin, it is easily broken into many plates, like the broken eggshell still on an “unpeeled” hardboiled egg. Some sections are enormous, like the Pacific plate we here live on. Some are not so expansive, like the Burma microplate involved in December’s earthquake.
But they ride and they ride and they ride, relentlessly. All over the planet the plates slowly but surely ride along the slow-moving hot gooey mantle below, speeding along at just inches a year.
The plates can slide by each other like here at the San Andreas Fault. They can separate from each other, like in the horn of Africa. Or they can plunge into and below each other as they do in Indonesia and Japan and South America.
Their slow but unsteady movements lift great mountains and continents, help form hills and valleys and island chains, recycle life-giving minerals and gases. There is nary a geographical feature on the entire globe unaffected by the mighty tectonics. They make this planet what it is.
But if we had a thinner, weaker crust, this place would be the proverbial hell on earth. Imagine massive earthquakes all the time. Imagine volcanoes everywhere spewing endlessly their choking gases. Imagine being inundated with new lava flows all over, all the time.
If our crust were thicker and our innards cooler, we would have no plate tectonics. If this were to happen now, erosion would sheer down great mountains and hills and fill valleys until we were essentially flattened into a water-covered planet, a water world.
The big picture here is that the crust and guts of our planet just as they are now, both of which undeniably combine to give us the occasional devastating and deadly earthquake and tsunami, are also the foundation of all the things we find beautiful about this planet.
And fair warning to us all: It will happen again. Movement is necessary. We just have to learn how to live with it. And it can be done.
What is especially tragic about the December tsunami is that we humans might have saved a lot of those lost lives. How?
Of all the planets in the universe we know our home the best. We know that shifting oceanic plates and undersea landslides and above-water coastal landslides trigger tsunamis. We know they take a certain time to reach a destination.
Moreover, we know now how to communicate on a global scale. If there had been a warning system set up around the Bay of Bengal, as there is in the Pacific basin, many geologists believe hundreds of thousands of people might have been warned early enough that they literally could have walked away before the walls of water swept in.
Perhaps the best thing to come of such “natural disasters” on our planet is the way it transforms many of us into unselfish, caring folk. The outpouring of help and prayer and support from all over the world for complete strangers was and is genuinely moving. Maybe we can’t bring a man’s wife and baby boy back to life, but we can help rebuild his home and comfort him while he grieves.
Yes, we live on the best imaginable planet, but even here things don’t always go according to our plans. But we can help each other through these distressing times and maybe make the planet even better for it.