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July, 2005 |
Gonzalez and Richards Chapter Four |
Posted by Gerald Vreeland at 7/18/2005 7:35:00 AM (0 comments left) |
Greetings again Cosmophiles! Once upon a time, back in the fall of 1996, I had some special international training in |
Meanwhile, back in
Chapter 4
The fourth chapter of Gonzalezâ and Richardsâ The Privileged Planet, is entitled âPeering Up.â And so I thought I would put quill to parchment (metaphorically speaking, of course) and do a brief description, analysis and synthesis of it. Last time, you will recall, we were âPeering Down,â and despite recent events in
This chapter has some of that as well as we look the other direction. Remember, their thesis is that there is a direct correlation between measurability and habitability. Because of that, it is necessary to have a medium through which we can see. The earthâs atmosphere is rather uniquely suited for that because although it is thick enough to burn up most meteorites and deflect the nastiest of solar rays, it is transparent enough to look through and observe the cosmos.
Another point has to do not with the speed of light, but the speed of dark! As a kid, I crawled down the neighborâs well and looked up in broad daylight and saw the stars. Facts are facts though, we probably wouldnât have thought of ways to see the stars in the day had there been no night wherein they force themselves on our awareness. One of the best ideas going is that the earth doesnât always have one face toward the sun â thus cooking everything on one side and freezing everything on the other. But the other side of that equation is that when the sun sets and the lights dim, we can see things not available to us normally during the day. Even that other obnoxious orb, the moon, doesnât really mess stargazing up that much â and we recall how much benefit it actually performs in everything from oceanic circulation to clam digging!
Another cool thing has to do with what the atmosphere allows through and what it prohibits. It allows most rays of visible light â what a coincidence! â and radio wavelengths, but it stops a lot of dangerous x- and gamma-rays, etc. Interestingly, 40% of the sunâs energy is transmitted at the level of ânear-ultraviolet, visible, and near-infrared spectra â the light most useful to life and sightâ (p. 66).
Photons are cool little guys â well actually theyâre pretty hot; but, they have to hit the planet just right or you can neither see nor live. âPhotons with too much energy would tear molecules apart, while those with too little energy could not trigger chemical reactions . . . So stars that donât emit the right sort of radiation in the right amounts wonât qualify as useful energy sources for lifeâ (p. 67). And so that limits the kinds of stars, the distances from them and the types of atmospheres useful for measurability and habitability. By the time weâre done with this whole process we might find that Saganâs âPale Blue Dotâ is a group of one in the universe.
One of the greatest things about our planet is the closed nature of the system. We have what I think is a unique system of feedbacks and clear view â again, habitability and measurability. There are basically four reflective surfaces on the planet: they are ice, the oceans, the continents and the atmosphere. Of course, they all change: seasonally and over the eons, the ice percentages change. Also, the atmosphere moves from more reflective and thus radiation and heat reducing (cloudy) to less reflective and more absorptive and thus heat retaining (clear). If you will indulge me on one of those geologic/astronomical time quotes:
For example, say the Sun brightens significantly over a few million years. If no other part of the system counteracts this, Earth will heat up, possibly with disastrous consequences for life. The polar ice caps could melt, causing Earth to deflect less of the Sunâs energy, leading to a spiraling cycle of overheating that over time could evaporate the oceans. But such a gloomy scenario ignores counterbalancing factors. The environment might compensate by increasing cloudiness and precipitation. These would reflect the excess solar energy back into space and encourage plant growth, thereby sequestering carbon dioxide, which might otherwise lead to a sweltering atmosphere. We call such stabilizing forces negative feedbacks (p. 69).
With statements like that, it makes it pretty difficult to believe that anything the industry of the human-insect does is going to contribute significantly to global warming, cooling â or slowing the impending ice-age for that matter. . . .
But it is not just the inanimate âGaeaâ that responds. There is also a reciprocal relationship between climate and biota of the most minute proportions â and we saw what the larger animals do when threatened by, say a tidal wave â they get their little furry and scaly bodies right out of harmâs way, donât they?
Scientists have only recently recognized other important links between life and the global climate. One such process involved the formation of cloud condensation nuclei (CCN), small particles in the atmosphere around which water can condense to form cloud droplets. Although CCN are produced by both natural and anthropogenic processes, Lovelock was among the first to link biologically produced CCN to the climate. Phytoplankton, such as Emiliana huxleyi, produce dimethyl sulfide, the first step in a chemical chain to build the CCN. Phytoplankton respond to a warming ocean surface by producing more dimethyl sulfide, which concentrates more CCN and enhances the albedo of marine stratus clouds. Reflecting more light back into space cools the ocean below. Higher carbon dioxide levels also stimulate production of dimethyl sulfide and CCN (p. 72).
Wow! That means that even the little critters in the oceans are helping us to keep cool â or to warm up if the glaciers get too close!
The authors then talk about the nature of the dusty atmosphere during the ice ages and how things are clearer now that we have clouds and warm/cold rains and snow and diversity in the climate. It all helps to scrub the atmosphere squeaky clean. Nice place to see, nice place to live. . . .
The discussion then shifts to what can be learned from the occasional (hard) extraterrestrial visitors that we have. When comets and meteorites visit us we get something of a glimpse of another world â fortunately, if they are really big, we can see them because of our clear atmosphere and thus, catalogue them. Remember that these guys are still of the school of thought that says that a nearly P/K event was what killed off such among our friends as the T. Rex. Alright, do we have to worry about one killing us off? Not really, but within a very few years we will have the technology to deflect anything that gets too close. Remember, it was only a couple of years ago that one of P/K size came within a million miles. It may seem like hardly across the street to you; but, it is only a little over four times the distance to the moon â and weâve already been there and back a few times.
Some space rocks seem to be pulled out of the asteroid belts by Jupiter and tossed our direction. Some of them appear to come from deep space and analysis of their contents tells us much about the universe prior to the development of the sun (well, according to these guys). While telling us of some of the richest places to hunt for landed meteorites, we are also told about the up-side of the gas giant planets: because of their size, a lot of space junk hits them instead of us â bigger target, stronger gravity. Also, they take a lot of space junk and launch it into deep space because of the gravity. A near miss in the wrong direction with Jupiter is a slingshot ticket to another star-system. However, besides being interesting â weâve all watched some great shooting star shows â the little devils help us out as well â we know that comets have ice in them; but so do space rocks:
Asteroids are a subtle contributor to Earthâs habitability â we need them early on to deliver water and organics, but not too many later on, since they have an unfortunate tendency to extinguish life. This most habitable of circumstances left us a small remnant population of asteroid remains to study the formation of the Solar System and then preceding history of the production of elements within stars. Just enough meteorites are still delivered to Earth to make studying them a practical endeavor (p. 78).
So next time you try to lose an Imperial Star Destroyer in an asteroid field, just thank your lucky falling stars that these little â and not so little! â guys have their place in Godâs cosmos:
Who would have guessed that the asteroid belt, which first seemed like a failed experiment in planet-building or a dangerous planetary junkyard, should play a role not only in Earthâs habitability but in scientific discovery as well? As we learn more about the seemingly accidental features of our atmosphere and Solar System, we begin to recognize a trend: The Earth system offers not only a habitat but also a great viewing platform for its inhabitants. Because the processes that produce such a happy planetary state are intricate and interdependent, Earth is likely to be a very rare kind of place (p. 79). Indeed, we might be unique! God seems to have had some particular things in mind for the Pale Blue Dot. |