Hot Jupiters

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Jim</i>
<br />You posted above that molecules of hydrogen have a molecular speed that exceeds the escape velocity on Earth. How do you determine this? The molecular speed must be something other than molecular thermal speed. Thermal speed is less than escape velocity.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">That's actually a pretty good question.

Consider the conditions in the early solar system just after fission from the Sun. The proto-Earth would be much larger than the present Earth (because of all the hydrogen), and a bigger planet with a given mass has a smaller surface escape velocity. It must also have been much hotter, close to the temperature of proto-Sun's surface. That would put the hydrogen molecular speed above, or at least close to, escape speed (several km/s).

However, actually exceeding escape speed is not necessary because of all the collisions between molecules. Whatever the mean molecular speed, there will always be some molecules near the top of the atmosphere with greater than the mean speed by enough to escape.

Even today, Earth still has a residual escaping hydrogen tail. -|Tom|-

TVF, With all the solar wind that reaches the gravity field of Earth how do you know where the hydrogen tail you are observing is protons from the sun or hydrogen from the Earth? Is data in existance that shows molecules departing from Earth rather than plasma from solar wind? It seems to me particles from the sun would be different than molecules from Earth but maybe not.

Solar wind could also play a role in s*****ing the inner planets of their hydrogen early on.

Mark Vitrone

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Jim</i>
<br />With all the solar wind that reaches the gravity field of Earth how do you know where the hydrogen tail you are observing is protons from the sun or hydrogen from the Earth?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">(1) The compositions are different. (E.g., protons are not hydrogen atoms.) (2) The tail exists inside Earth's shadow in places where no solar wind can penetrate. -|Tom|-

TVF, I know protons(h+) and hydrogen molecules(H2) are different. The question is: is the tail molecules or not? Molecules would come from Earth and protons(hydrogen atoms)would come from the sun. Since the shadow of Earth is moving it a fraction of the solar wind with the Earth how can it block all the wind? Is there a paper on this detail?

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Jim</i>
<br />is the tail molecules or not?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Because it is neutral hydrogen, it is a molecule by definition.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Since the shadow of Earth is moving it a fraction of the solar wind with the Earth how can it block all the wind?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Solar wind travels much faster than Earth.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Is there a paper on this detail?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Many, in that field, which I do not follow. If you don't have access to the journals, try the NASA abstract service. -|Tom|-