The moon is shrinking, and Earth is to blame for how the moon’s crust has cracked.

Scientists reported the shrinkage in 2010, when researchers, led by Thomas R. Watters of the Smithsonian’s National Air and Space Museum, picked out cracks in images taken by NASA’s Lunar Reconnaissance Orbiter.

They counted 14 ridges, formed when one side of the fracture slips over the other, but the orbiter’s high-resolution camera had covered only about 10 percent of the moon’s surface. Five years later, more than three-quarters of the surface has been photographed, and the scientists now count more than 3,200 ridges.

If the moon were shrinking uniformly, then the cracks and ridges should be pointed every which way. Instead, Watters and his colleagues found that around the equatorial and mid-latitude regions, there was a preponderance of north-south ridges, while near the poles, the faults tended to run east-west. What researchers figured out is that the tidal forces of the Earth pulling on the moon generated enough stress to break the moon’s crust in the observed pattern.


On track for the hottest year

An El Niño in the Pacific Ocean and rising temperatures caused by climate change have put the world on an almost irreversible path to its warmest year on records dating back to 1880.

Global temperatures from January to August were 1.5 degrees Fahrenheit above the 20th-century average and the warmest first eight months of any year in the books, the National Centers for Environmental Information said. Deke Arndt, chief of the center’s monitoring branch in Asheville, N.C., said, “Long- term climate change is like climbing a flight of stairs. El Niño is like standing on tippy toes while you are on one of those stairs.”


Salmon discovery 11,500 years old

Salmon fishing in North America dates from the end of the last ice age, a study reports.

In a cooking hearth at the Upward Sun River archaeological site in central Alaska, researchers discovered salmon remains that are 11,500 years old. The hearth sits atop a grave in which two infants were buried.

The remains are the earliest confirmed evidence of salmon consumption in North America, the researchers said. “Before this, we really had no idea that Paleo-Indians were using salmon or fish of any kind,” said Carrin Halffman, an archaeologist at the University of Alaska Fairbanks and an author of the report.


An evolutionary step for chameleons

Chameleons have five digits, but in each hand and foot, these digits are split into two “bundles.” The arrangement permits them to grasp branches and climb with ease, excellent adaptations for life in the trees.

A study reports that the angle between the “bundles” in the tree-dwelling species depends on a large number of previously unknown skeletal elements in the wrist and ankle that fuse together as the embryonic chameleon develops. The fusion produces a ball-and-socket joint that chameleons can use to rotate their bodies while reaching for branches.

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