out as a vast cloud of gas and dust. Something caused this cloud to collapse. Perhaps it was a collision with another cloud (which happens fairly often in the Galaxy), a blast from a nearby supernova, or the wind from a red giant star that pushed on the cloud that prompted the collapse.
Whatever the initial cause, as it collapsed, the cloud flattened due to centrifugal force and friction. As the matter in the cloud formed a disk, particles of ice and dust collided, stuck together, and grew. Eventually, over some hundreds of thousands of years, the pieces grew large enough to attract material with their own gravity. When this happened, the disk particles were quickly sucked up by the forming planets. By this time, the Sun was finishing its own formation, and a super-solar wind started. This wind blew any remaining material away, leaving something that looked a lot like the solar system we see today. This theory has recently been strongly supported by many astronomical observations, including those of young solar systems by the Hubble Space Telescope.
The creationists, however, say that the solar system shows several characteristics that are not consistent with the scenario outlined above. The ICR has an educational course available through its web page called “Creation Online,” available at http://www.creationonline.org/intro 88680.htm. In it, ICR officials list several of these arguments. All of these claims are wrong. What follows are verbatim quotations from “Creation Online.”
If the planets and their 63 known moons evolved from the same material, they should have many similarities. After several decades of planetary exploration, this expectation is now recognized as false.
Actually, this claim is false. The disk that formed the solar system was not homogeneous; that is, it wasn’t the same throughout its extent. That would be a silly thing for a scientist to assume, since it’s clear that near the center of the disk the Sun would heat the material, evaporating off the ice, while near the edge far from the Sun the ice would remain intact.
Astronomers have known for decades that the disk must have had different materials distributed along it, because the outer planets and moons are much different than the inner ones. The outer moons have more ice in their composition, for example, perfectly consistent with a disk that had a distribution of materials along it. To be generous, this argument is at best disingenuous on the part of the ICR. If the collapsed disk theory hadn’t jibed with that most basic observation, it would have been thrown out before it ever got proposed.
Since about 98% of the sun is hydrogen or helium, then Earth, Mars, Venus, and Mercury should have similar compositions. Instead, much less than 1% of these planets is hydrogen or helium.
When they formed, the inner planets probably did have a much higher amount of these gases. However, the gases are very lightweight. Imagine flicking your finger on a small pebble. It goes flying! Now try that on a station wagon. The car won’t move noticeably, and you may actually damage your finger. The same sort of process is going on in the Earth’s atmosphere. When a molecule of nitrogen, say, smacks into a much smaller hydrogen atom, the hydrogen gets flicked pretty hard, like the pebble. It can actually pick up enough speed to get flung completely off the Earth and out into space. When the nitrogen molecule hits something heavier, like another nitrogen molecule, the second molecule picks up less speed, like the station wagon in our example. It pretty much stays put. After a long time, the lighter atoms and molecules suffer this same fate; they all get flung away from the Earth. Over the lifetime of the Earth, all of the hydrogen and helium in the atmospheres of Earth, Venus, and Mars have basically leaked away, leaving the heavier molecules behind.
Jupiter and the other outer planets retained their lighter elements for two reasons: they are colder, and they are bigger. A colder atmosphere means the collisions occur at slower speeds, so the lighter elements don’t get lost to space. A bigger planet also has more gravity, which means the planet can hold on more tightly to its atmosphere. A small hot planet like Earth loses its hydrogen; a big cold one like Jupiter does not.
So the collapsing cloud theory predicts that
All planets should spin in the same direction, but Venus, Uranus, and Pluto all rotate backwards.
According to the collapsing-cloud theory, the planets should all spin in the same direction in which they orbit the Sun because the initial disk spun that way. Anything forming in that disk should spin in the same direction. However, Venus rotates backwards, and Uranus rotates on its side! How can the disk theory explain that?
Actually, the answer is simple: it doesn’t. The disk theory concerns only how the planets
We know for a fact that cosmic collisions occur. We had repeated graphic examples of this in July 1994, when the comet Shoemaker-Levy 9 broke into dozens of pieces and slammed repeatedly into Jupiter, releasing more energy than could humankind’s entire nuclear arsenal. Had the comet hit Earth instead of Jupiter, it would have been a catastrophe of, well,
And even this collision is small potatoes. In the early past, when the disk was forming into planets, gravitational interactions would have been common. Two planets forming too closely together would affect each others’ orbits, and the smaller one might actually get flung into a wildly different orbit. This orbit could have sent it on a collision course with another planet. An off-center, grazing collision could physically tilt a planet, changing the axis of rotation, in much the same way that poking a spinning top off-center causes the axis to wobble.
In the case of Uranus, a large collision is what most likely knocked it on its side. For poor Venus, whatever collided with it knocked it almost completely heels-over-head. To us it looks like Venus is upside-down and spinning backwards.
Ironically, this catastrophic view of planetary dynamics is more biblical than classically scientific. For many years, scientists avoided using catastrophes to explain events, since they were hard to reproduce, difficult to analyze statistically, and smacked of biblical events. In the end, though, science learned that catastrophes do happen, which is its strength. When presented with evidence contrary to the theory, science learns and grows.
All 63 moons in the solar system should orbit their planets in the same sense, but at least six have backward orbits. Furthermore, Jupiter, Saturn, and Neptune have moons orbiting in both directions.
This one is really easy to explain. Some of the moons of the planets formed at the same time as the planets and orbit their parent bodies in the “correct” sense, that is, in the same direction that the planet spins and orbits the Sun. However, it’s possible, although generally not easy, for a planet to capture moon-sized objects. If the conditions are just right, it’s not only possible but rather common that such a captured moon would orbit the planet in the opposite direction. Jupiter and Saturn both have moons that orbit backwards, or retrograde. All of these moons orbit at large distances from their planet, as is expected in a capture event as well.
Again, using this as a creationist argument is disingenuous on their part. Retrograde moons have been known about and explained for many decades.
The sun turns the slowest, the planets the next slowest, and the moons the fastest. But according to evolutionary theories, the opposite should be true. The sun should have 700 times more angular momentum than all the planets combined. Instead, the planets have 50 times more angular momentum than the sun. The sun has 99.9% of the total mass of the solar system, but 99% of the total angular momentum is concentrated in the larger
