Q&A: Does the Moon’s Shallow Dust Layer Support a Young-Earth Model?
September 1, 2014
From Nathan in Newry, Northern Ireland
A young-earth creationist pastor at one of the churches I regularly attend attacked my scientific viewpoint in one of his sermons. He said that NASA scientists tried to aim Apollo 11 so that it landed on the side of the crater because the scientists were scared that the lunar lander would sink in the 4.5-billion-years worth of dust that had gathered on the surface. However, when the astronauts landed, there was very little dust and the lander didn’t sink; therefore, the earth was 6,000 years old, proving the Bible right. I was wondering what your response to this would be?
This argument for a young Earth is based on measurements made by geophysicist Hans Pettersson in the 1950s. Pettersson used measurements of the quantity of nickel passing through dust filters atop Hawaii’s Mt. Mauna Loa to estimate the influx of meteoritic material.1 Nickel is more rare in terrestrial dust than in meteorites, where it comprises 2.5 percent of meteoritic material. Based on this data, Pettersson assumed all the nickel he collected came from space and used it to calculate that some 5 million tons of space dust settles on Earth per year. If Pettersson’s calculations were correct, then our 4.5-billion-year-old Moon should be covered in 35 feet of space dust.
The lunar landings, however, revealed that only an eighth of an inch to three inches of loose surface lunar dust rests on the Moon. Again, if Pettersson’s measurements were accurate, this would imply a lunar age of only millions of years. Some young-earth creationist leaders attempted to lower the Moon’s age even further—down to 10,000 years—by exploiting the large errors and uncertainties in Pettersson’s results to skew the numbers toward as youthful a lunar age as possible.
Pettersson was aware his ground-based instrument measured not only infalling space dust but also atmospheric material generated by wind erosion and volcanic eruptions. Fortunately, a decade after Pettersson published his estimates, scientists made direct satellite measurements of cosmic dust inflow. Instead of a 5-million-ton annual accumulation on Earth, only 23,000 tons were indicated (1,700 tons per year for the Moon).2 This result was known before the Apollo 11 mission. NASA, therefore, was not at all concerned about the lunar lander disappearing in dust.
The most accurate measurements of micrometeorite influx to date were performed in 1993 and showed 40,000 tons annual accumulation for Earth (3,000 for the Moon).3 This quantity translates into an average of 1.2 inches of dust on a Moon that’s 4.5 billion years old. When other sources of inflow and outflow are considered (decomposition from ultraviolet radiation, other erosion sources, compactification of older dust, inflow from larger meteorites and comets, and outflow from asteroid and meteorite impacts large enough to expel debris away from the reach of the Moon’s gravity), the measured one-eighth to three inches of lunar dust adds up to a lunar surface age of about 4.5 billion years. This value is in agreement with the maximum degree of erosion seen on lunar craters, with the abundance of argon in the lunar atmosphere and rocks, and with radiometric dates of lunar rocks.4
Nathan, your young-earth pastor may be encouraged to know that a 4.5-billion-year-old Earth does not disturb the doctrine that God created in six literal days. One of the four literal definitions of the Hebrew word yôm—translated as “day”—is a long but finite time period. Also, yôm is the only word in biblical Hebrew that carries the definition of an epoch of time. Your pastor also may be pleased to know that long creation days in no way disturb the doctrine that all humanity is descended from one man and one woman whom God specially created less than several tens of thousands of years ago.
Subjects: Scientific Evidence for an Old Earth
- Young-earth creationists usually cited this popular-level article: Hans Pettersson, “Cosmic Spherules and Meteoritic Dust,” Scientific American 202 (February 1960): 123–32.
- J. S. Dohnanyi, “Interplanetary Objects in Review: Statistics of Their Masses and Dynamics,” Icarus 17 (August 1972): 1–48.
- S. G. Love and D. E. Brownlee, “A Direct Measurement of the Terrestrial Mass Accretion Rate of Cosmic Dust,” Science 262 (October 22, 1993): 550–53.
- G. Brent Dalrymple, The Age of the Earth (Stanford, CA: Stanford University Press, 1991), 193–256; John S. Lewis, Physics and Chemistry of the Solar System (San Diego, CA: Academic Press, 1995), 379–93.