by Ann » Tue Jun 22, 2010 6:41 am
I think it is interesting to have an occasional image of the Earth here, if only to remind us that the Earth is a part of the cosmos, too.
However, I think that whenever possible, APOD pictures of the Earth should compare the Earth with other known planets. What about the Earth's volcanism compared with the volcanism on Mars and Venus, for example? Well, Mars also has volcanoes, but there is so much less present-day volcanism on Mars than on the Earth. While the Earth is still basically molten and bubbling, Mars is like a decrepit old person, getting ever stiffer and more rigid.
Venus, or so someone said, may have suffered a series of humongous eruptions which dumped all that "atmosphere in the atmosphere" which in turn started a runaway greenhouse effect on the planet. Or so I read someplace, as I said. I'm sure that this hasn't been proved in any way, and my guess is that Chris Peterson may disapprove of the theory!
Anyway, my point is this: The Earth is probably once again a Goldilock world, when it comes to volcanism, too. We've got just the right amount of it. Life probably needs, or at least strongly benefits from, volcanism, if there is not too much of it. Just the right amount of volcanism recycles the world, bringing fresh nutrients and other necessary stuff to the surface. Venus and Mars hasn't got the kind of volcanism that we have got, and this may contribute to their barrenness.
Ann
I think it is interesting to have an occasional image of the Earth here, if only to remind us that the Earth is a part of the cosmos, too.
However, I think that whenever possible, APOD pictures of the Earth should compare the Earth with other known planets. What about the Earth's volcanism compared with the volcanism on Mars and Venus, for example? Well, Mars also has volcanoes, but there is so much less present-day volcanism on Mars than on the Earth. While the Earth is still basically molten and bubbling, Mars is like a decrepit old person, getting ever stiffer and more rigid.
Venus, or so someone said, may have suffered a series of humongous eruptions which dumped all that "atmosphere in the atmosphere" which in turn started a runaway greenhouse effect on the planet. Or so I read someplace, as I said. I'm sure that this hasn't been proved in any way, and my guess is that Chris Peterson may disapprove of the theory! :wink:
Anyway, my point is this: The Earth is probably once again a Goldilock world, when it comes to volcanism, too. We've got just the right amount of it. Life probably needs, or at least strongly benefits from, volcanism, if there is not too much of it. Just the right amount of volcanism recycles the world, bringing fresh nutrients and other necessary stuff to the surface. Venus and Mars hasn't got the kind of volcanism that we have got, and this may contribute to their barrenness.
Ann