Dr. Api
Föstudagurinn 1. september 2006 kl. 0:21
Flokkur: Spjaldiš
Bacteria don't have a space program. Therefore, they're fucked when the Sun expands. We're not.
Don't bet on this.
Back in the 1960s and 70s, there were a number of papers written by astronomers about the Earth's "dust tail", equivalent to a comet's tail, and made of particles of the outer atmosphere blown off by the solar wind. This was of some significance for long exposures in the part of the sky behind the tail.
The studies showed that the Earth's dust tail is mostly gases, but also includes small dust particles, including particles the size of bacterial spores. Further study showed that the upper atmosphere does in fact have a small number of such particles, including bacterial spores. More studies showed that many bacterial spores can survive conditions in space for a rather long time.
So the Earth is spewing a tail of gases, dust and bacterial spores into interplanetary space. The solar wind blows this outward. A small amount hits the outer planets (and "dwarf planets" ;-), but most of it escapes the Solar System.
This has probably been going on for 3 to 4 billion years. The Earth makes an orbit of the galaxy in about 220 million years. So we've made a dozen or more circuits of the galaxy, broadcasting bacterial spores the whole time. Calculations show that these spores by now have totally permeated the galaxy, and may have reached the Magellanic clouds, but probably not more distant galaxies.
There's a certain amount of conjecture here, of course. We don't actually know that bacterial spores are viable for the millions of years that it would take to reach other star systems. Few of them would ever encounter another planet where they could wake up and start living again. But over a few billion years, with a few billion spores per year (not much mass, really), small chances add up.
Some have suggested that this could be how life reached Earth. Google for the "panspermia" hypothesis for more information. There could well be other planets in the galaxy that are similarly broadcasting bacterial spores. Some of them could have been doing it for 12 billion years or so.
It's interesting to think about. Over billions of years, the Earth may not be as isolated as we might like to believe.
Don't bet on this.
Back in the 1960s and 70s, there were a number of papers written by astronomers about the Earth's "dust tail", equivalent to a comet's tail, and made of particles of the outer atmosphere blown off by the solar wind. This was of some significance for long exposures in the part of the sky behind the tail.
The studies showed that the Earth's dust tail is mostly gases, but also includes small dust particles, including particles the size of bacterial spores. Further study showed that the upper atmosphere does in fact have a small number of such particles, including bacterial spores. More studies showed that many bacterial spores can survive conditions in space for a rather long time.
So the Earth is spewing a tail of gases, dust and bacterial spores into interplanetary space. The solar wind blows this outward. A small amount hits the outer planets (and "dwarf planets" ;-), but most of it escapes the Solar System.
This has probably been going on for 3 to 4 billion years. The Earth makes an orbit of the galaxy in about 220 million years. So we've made a dozen or more circuits of the galaxy, broadcasting bacterial spores the whole time. Calculations show that these spores by now have totally permeated the galaxy, and may have reached the Magellanic clouds, but probably not more distant galaxies.
There's a certain amount of conjecture here, of course. We don't actually know that bacterial spores are viable for the millions of years that it would take to reach other star systems. Few of them would ever encounter another planet where they could wake up and start living again. But over a few billion years, with a few billion spores per year (not much mass, really), small chances add up.
Some have suggested that this could be how life reached Earth. Google for the "panspermia" hypothesis for more information. There could well be other planets in the galaxy that are similarly broadcasting bacterial spores. Some of them could have been doing it for 12 billion years or so.
It's interesting to think about. Over billions of years, the Earth may not be as isolated as we might like to believe.
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