Is the Earth getting lighter?
- Thread starter Archean
- Start date
LinkedKube
Posts: 3,385 +55
Nice, I'd like to close the gap in between my neighbors window and my own. In about 200,000 years that is...
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scarborough
Posts: 10 +0
Well that can't be good.
Doctor John
Posts: 200 +15
Antihydrogen?
I am having a little trouble with the piece about hydrogen being so light that it escapes - surely it still experiences (tiny) positive gravity?
I am having a little trouble with the piece about hydrogen being so light that it escapes - surely it still experiences (tiny) positive gravity?
Archean
Posts: 5,650 +102
To make it easy, thermal escape mechanisms dictate that the more massive a molecule of a gas is, the harder it will be for it to gain 'escape velocity' and leave atmosphere. But it also means the lighter a gas molecule is (e.g. hydrogen) it will gain escape velocity and leave more easily when compared to something like carbon dioxide.
Escape velocity will be different for a planet with higher mass from one which is much lighter. Add to this the position of a planet, the closer it is to a star the hotter its atmosphere will be, whereas the farther it is the cooler it will be. Hence, on cooler planet there will be less chance of gas molecules gaining escape velocity due to 'cooler temperatures'.
Escape velocity will be different for a planet with higher mass from one which is much lighter. Add to this the position of a planet, the closer it is to a star the hotter its atmosphere will be, whereas the farther it is the cooler it will be. Hence, on cooler planet there will be less chance of gas molecules gaining escape velocity due to 'cooler temperatures'.
Doctor John
Posts: 200 +15
hydrogen attraction
If hydrogen is inclined to escape into space, against gravity, how come stars (mainly hydrogen) condense from interstellar gas, under gravity?
If hydrogen is inclined to escape into space, against gravity, how come stars (mainly hydrogen) condense from interstellar gas, under gravity?
learninmypc
Posts: 9,679 +724
Thanks. The OP should of said such.
Archean
Posts: 5,650 +102
Stars are born within the clouds of dust and scattered throughout most galaxies. A familiar example of such as a dust cloud is the Orion Nebula, revealed in vivid detail in the adjacent image, which combines images at visible and infrared wavelengths measured by NASA's Hubble Space Telescope and Spitzer Space Telescope. Turbulence deep within these clouds gives rise to knots with sufficient mass that the gas and dust can begin to collapse under its own gravitational attraction. As the cloud collapses, the material at the center begins to heat up. Known as a protostar, it is this hot core at the heart of the collapsing cloud that will one day become a star. Three-dimensional computer models of star formation predict that the spinning clouds of collapsing gas and dust may break up into two or three blobs; this would explain why the majority the stars in the Milky Way are paired or in groups of multiple stars.
Source
This is also good read, indirectly addressing the issue of star's loss of mass as it ages.
Doctor John
Posts: 200 +15
Yes, I agree, the collapse IS due to gravitational attraction, hence my wondering why hydrogen would escape into space (unless it had magically lost it's mass!)
It shouldn't make any difference whether there are "knots of sufficient mass" or indeed a tenuous gas verging on vacuum, as found at the edge of the atmosphere, as gravity is a cumulative and long-range effect.
Any massive particle (e.g. hydrogen or helium atom) within range of a large body (like the Earth) will be attracted, not repelled.
It shouldn't make any difference whether there are "knots of sufficient mass" or indeed a tenuous gas verging on vacuum, as found at the edge of the atmosphere, as gravity is a cumulative and long-range effect.
Any massive particle (e.g. hydrogen or helium atom) within range of a large body (like the Earth) will be attracted, not repelled.
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