I have got to stop following links in e-mails from AIG. Today I read the most bizarre article by Dr. Danny Faulkner, an astrophysicist who must have slept through his celestial mechanics courses. Dr. Faulkner discusses the leap second that will be added at 23:59:59 UTC (GMT) on June 30. He notes correctly that the rotation of the Earth is slowing down, and the moon is consequently drifting farther from the Earth. He then observes,
Finally, there is a long-term secular (non-periodic) slowing in the earth’s rotation caused by the tidal interaction of the earth and moon. As the earth slows its rotation, the moon spirals away from the earth. Therefore, in the past the earth spun more rapidly and the moon was much closer to the earth. Direct computation shows that the earth and moon would have been in contact about 1.3 billion years ago. Even a billion years ago the moon would have been so close to the earth that tides would have been a mile high. No one–including those who believe that the earth is far older than a billion years–thinks that tides were ever that high or that the moon and the earth touched a little more than a billion years ago.
However, since the earth and moon are only thousands of years old as the Bible clearly indicates, the long-term change in the earth-moon system is no problem. Indeed, what we see in the interaction between the earth and moon offers powerful evidence that the earth and moon are young.
I do not know the nature of the “direct computation,” but I would bet that it is based on the radius of the moon’s orbit increasing at a constant rate. Not obviously a good assumption; an article from Cornell University (which has a scientific reputation at least as distinguished as that of AIG) notes,
The exact rate of the Moon’s movement away from Earth has varied a lot over time. It depends both on the distance between the Earth and the Moon, and the exact shape of the Earth. The details of continents and oceans moving around on Earth actually change the rate, which make it a very hard thing to estimate. The rate is currently slowing down slightly, .…
Worse, look at Dr. Faulkner’s statement that “the earth and moon would have been in contact about 1.3 billion years ago.” An absolutely remarkable statement from a person who purports to have a PhD in physics and astronomy! Has he never heard of Roche’s limit? Roche’s limit is the smallest radius that a large satellite can maintain without being torn apart by tidal forces caused by the gravitational field of the main planet. According to NASA, Roche’s limit for the Moon is about 20 000 km, so I can assure Dr. Faulkner that the Earth and the Moon have never been in contact – not 1.3 billion years ago, not ever. When the Moon was formed, it had to have been formed outside Roche’s limit, and then it drifted away from the Earth at a rate that is not a constant and therefore not amenable to simple calculations.
Modern astronomy is not threatened, and the Earth is not young.