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Lots of Ice On Mars
Total Recall writes: "The Mars Odyssey spacecraft is finding large
amounts of hydrogen in the southern hemisphere of
Mars. This strongly indicates the presence of
water ice (since H2O is both common and very stable). The data samples about the upper meter or so of the Martian surface. This apparently extends from the south polar cap up to about 60 south latitude. It suggests a permafrost of mixed ice and dirt."
One neat thing about the info released today is that it supports what Richard Hoagland has been saying for months. See pictures here and here.
At his website you can find out how this validates the theory that Mars was once the satellite of the planet that formed the asteroid belt when it broke up for unknown reasons. (The pattern of water is indicative of tidal action.)
Oil of Wormwood: because absinthe makes the heart grow fonder.
As a general plug I would suggest to anyone interested in the possibilites of terraforming mars to read Kim Stanley Robinson's 3-part Mars series. All 3 won the Hugo (or was it nebula?). Great books.
This is actually an exaggeration from hollywood -- the meteors left in our solar system are not large enough to cause a global extinction of a race as tenacious as humans.
Well, that's a relief! Unfortunately, it's complete and utter nonsense. A hit by a somewhat sizeable asteroid or comet would not only wipe out the human race, but probably most lifeforms on earth. Oh, and it's not size that matters, it's kinetic energy, which is 0.5*m*v^2. Dependent on mass (~size), but more on velocity, since that gets squared.
Hypothetical but realistic example: take a (spherical) piece of rock with a radius of 10 km, hitting the earth at 50 km/s. Assuming a density of 4000 kg/m^3, that gives us a mass of 1.68*10^16 kg. The kinetic energy is roughly
2.1*10^25 Joules. That's the equivalent of 4.67 billion megatons of TNT. Or 467,000,000,000 Hiroshima bombs all set off at the same moment.
Can someone do a sanity check on this? It seems shockingly high.
Assumptions:
1 Megaton TNT ~ 4.5*10^15 J
Hiroshima bomb ~ 10 kilotons of TNT
Fact: volume of a sphere is (4/3)*pi*r^3.
MSN 8: Now Microsoft even has bugs in their ad campaigns.
The good news is that there is only about a one in three billion chance of a rock that size hitting the earth this year. These are long odds - but the chance is not zero.