Cryogenics And Planetary Science

A recent posting about cosmology and temperature got me thinking about something else. The science of very low temperatures is known as cryogenics. Strange things take place at temperatures close to absolute zero, -459 degrees Fahrenheit or -273.16 degrees Celsius, at which all of the molecular motion, which we perceive as heat, ceases. A tough and flexible sheet of rubber, for example, will become extremely brittle at such temperatures so that it shatters like glass.

In the posting about temperature and cosmology, I explained how this demonstrates that my version of string theory must be correct. But this extreme brittleness of materials at very low temperatures also has implications for planetary science. The universe in which we live is a very cold place, the average temperature of the universe as a whole is about 3 degrees above absolute zero. In other words, despite the brilliance of stars in the sky, cold is the rule and heat is very much the exception.

Let's consider the asteroid belt between the orbits of Mars and Jupiter, and also the famous systems of rings around the planet Saturn.

Almost all of the asteroids have irregular shapes. The two moons of Mars, Phobos and Deimos which appear to be asteroids that were captured by the planet's gravity, are roughly potato-shaped. This means that many asteroids tend to be held together by structural bonds, rather than primarily by gravity. A body held together by gravity, such as the earth or the moon, will be spherical in shape because this is the shape with the lowest energy state.

You can read the article about asteroids on http://www.wikipedia.org/ if you like.

The asteroids orbit the sun in roughly the same geometric plane as the planets. This arrangment could have only come about by various collisions and mutual gravitation among what is now the asteroids after debris was thrown in all directions by the supernova (exploding star) which preceded the Solar System. One plane eventually became predominant, the one in which the planets and asteroids orbit now.

Let's move out to the ring system around the planet Saturn. There are actually rings around all of the large outer planets; Jupiter, Saturn, Uranus and, Neptune, but none of the others can compare with the rings of Saturn.

The dynamics of the rings around Saturn have a lot in common with the asteroid belt. The particles making up the rings are very tightly aligned in one geometric plane, so that the rings are invisible when seen edge-on from earth. Like the asteroid belt, this can only have come about by an extended period of collision and mutual gravitation from a primordial cloud of debris in orbit around Saturn.

The major difference between the asteroids and the rings of Saturn is the size and number. Some asteroids, especially Ceres, can almost be considered as planets. Many asteroids are hundreds of kilometers in diameter. Saturn's rings, in contrast, are made up of mere grains with only a relative few bodies up to a few meters across. This is why the rings appear to be a solid surface from a distance.

But how did this come about, in two systems with dynamics that are so similar.

Let's consider cryogenics, and the extreme brittleness that occurs at very low temperatures. The average asteroid is not much more than twice the distance of the earth from the sun. That means that they do receive a considerable degree of warmth. Saturn and it's rings, in contrast, is about nine times as far from the sun as the earth.

What this means is that the matter which makes up the rings of Saturn is extremely cold. The rings of Saturn are so cold that cryogenics apply. The pieces of matter in the rings must have the extreme brittleness that is found at such low temperatures. I find that this explains why the matter composing the rings of Saturn are broken into pieces so that the rings appear as a solid surface.

The particles making up the rings were once something more like the asteroids, but various collisions with one another broke them apart due to this cryogenic brittleness.