Wednesday, February 1, 2012

From Cloud to Sun - Cloud

Molecular cloud jiggles like a soap bubble 

One of the great wonders of God's creation is how He takes an extremely cold cloud of sparsely distributed hydrogen molecules and lights it into the great flames of a brilliantly burning Sun.

The nearby Barnard 68 cloud allows astronomers to study the process in some detail. According to current view this nebula is a good candidate for a new star to be born some 100.000 years from now. (This is not a long time in astronomical scale. Let us remember humbly that our species homo sapiens sapiens has existed on planet Earth for less than 200.000 years and that the rise of higher human civilization began in Mesopotamia and Egypt about 5000 years ago. So time is relative, indeed.)

An anonymous wikipedia writer describes the cloud using a nice comparison to something that is familiar to us in everyday life:

If not disrupted by external forces, the stability of dust clouds is a fine balance between outward pressure caused by the heat or pressure of the cloud's contents, and inward gravitational forces generated by the same particles (see Jeans instability and Bonnor-Ebert mass). This causes the cloud to wobble or oscillate in a manner not unlike that of a large soap bubble or a water-filled balloon which is jiggled.

Here is an excerpt from an article that describes states of some objects in astrophysics:

Hydrostatic equilibrium or hydrostatic balance is the condition in fluid mechanics where a volume of a fluid is at rest or at constant velocity. This occurs when compression due to gravity is balanced by a pressure gradient force. For instance, the pressure gradient force prevents gravity from collapsing the Earth's atmosphere into a thin, dense shell, while gravity prevents the pressure gradient force from diffusing the atmosphere into space.

There is some energy in those hydrogen molecules (H2) even the temperature of the cloud may be as near to absolute zero as 16 Kelvin. In the emptiness even this movement is felt as physical pressure - Barnard 68 is half light years across with the mass of only two Suns so there is plenty of empty space. The tiny molecules are made of two hydrogen atoms comparing to which a feather is Titanic. Even so, they do have mass and thus gravity. There we have it, a "water generating" cloud jiggling in the space like a soap bubble.  Something like a balloon of water - except that water has two hydrogen atoms plus one oxygen atom H2O - some 500 light-years from us..

How to put it in fire?

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