Our corner of the Milky Way galaxy may be a bigger deal than scientists thought. The galaxy is shaped like a disk, with four major arms of stars, dust and gas spiraling out from the center. Our solar system lies at the edge of what’s called the Local Arm, which resembles a separate piece of an arm. Now, a paper in the journal Science Advances concludes the Local Arm is bigger than scientists thought. Researchers calculated that it stretches more than 20,000 light-years long, about four times what scientists had thought before. That’s still a lot shorter than the major arms. The work was done by analyzing radio-wave emissions with the Very Long Baseline Array, a series of Earth-based dishes.

Roman artifacts found in Okinawa castle

Archaeologists have found ancient Roman coins buried in the ruins of a 12th-century castle in Okinawa, and no one knows how they got there. Hiroki Miyagi, an archaeologist at Okinawa University who helped analyze the find, said that there was no evidence that there was trade between the Ryukyu Kingdom and the West. But, he added, “We know from documents and pottery shards that there was extensive trade with China and Southeast Asia from the 14th to the 19th century.” The coins, he suggested, arrived in Okinawa via China. “There is a possibility that Chinese traders got the coins from Muslim traders,” Miyagi said.

Abundant life in Hawaii’s twilight zone

Coral reefs in Hawaii’s oceanic twilight zone, where light still penetrates and photosynthesis occurs, are abundant and host a wide variety of life, a new study shows. A paper in the journal PeerJ said that the ecosystems, found in waters from 100 to 500 feet deep, host more than twice the amount of unique Hawaiian fish species as their shallow-water counterparts, and they are much more extensive than previously known. In a channel off the island of Maui, the team said they found the largest uninterrupted coral ecosystem ever recorded, measuring more than 3 square miles with some areas showing 100 percent coral cover.

Endangered frog rebounding in park

A native California frog once on the brink of extinction is making an encouraging comeback in Yosemite National Park. The Sierra Nevada yellow-legged frog — little more than 3 inches long and known for the coloring under its hind legs — was once the most abundant amphibian in the mountain range. Their numbers began to plummet roughly a century ago as they were gobbled up by nonnative trout stocked for fishing and struck by disease, but efforts to save the frog have led to a sevenfold increase in their numbers in Yosemite in the last 20 years.

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