This is where we go when we follow the water. Down it flows—that’s science—and we race it to the ocean. Not quickly enough. The stream dwindles to mud that shines and then dulls. I feel as if I can hear the waves wash the rocks, just past where the pastures rise. We were so close this time. We’ll try again another day. Tomorrow’s weather forecast says rain.
So what can this unusual library tell us? First, there is the simple parts list. The most common component was organic material, present in 40 of the 63 particles – exactly what is unclear, but it could be anything from pollen to sloughed-off bits of researcher. Quartz, found in 34 particles, came next, followed by carbonates (17 particles) and gypsum (14). “The minerals blow in,” says Coe. “They come from all over the world.” Other ingredients included air pollutants and fertiliser chemicals.
It’s a little out of the way. We love our new home but the location is relatively remote. Not Montana prairie far, and not Desolation of Mordor far, but you have to drive for almost fifteen minutes to get a gallon of gas or milk. We’re twenty-five minutes from the Interstate, so for the first time in decades I cannot sit on my porch and hear the hum of highway traffic. Are these the metrics that define civilization? Do you choose isolation or insulation?
The Earth and moon have two Trojan points, one leading ahead of the moon, known as the L-4 point of the system, and one trailing behind, its L-5 point.
The researchers computed that this second moon could have stayed at a Trojan point for tens of millions of years. Eventually, however, this Trojan moon’s orbit would have destabilized once our moon’s orbit expanded far enough away from Earth.
The resulting collision would have been relatively slow at 4,500 to 6,700 miles per hour (7,200 to 10,800 kph), leading its matter to splatter itself across our moon as a thick extra layer of solid crust tens of miles thick instead of forming a crater.
A number of explanations have been proposed for the far side’s highlands, including one suggesting that gravitational forces were the culprits rather than an impact from Francis Nimmo at the University of California, Santa Cruz, and his colleagues. Nimmo said that for now there is not enough data to say which of the proposals offers the best explanation for this lunar contrast. “As further spacecraft data and, hopefully, lunar samples are obtained, which of these two hypotheses is more nearly correct will become clear,” Nimmo said in a statement.