When Vikings came to America

It’s long been known that the Vikings were the first Europeans to make the epic journey to North America. Norse sagas from the 13th century recount how—hundreds of years earlier—seafarers sailed the Atlantic to a place they called Vinland, and in the 1960s archaeologists unearthed a Viking settlement at the northernmost tip of Newfoundland. Now a new study has pinpointed a precise date for the Vikings’ presence: 1021, exactly 1,000 years ago. To get that date, scientists examined three pieces of wood found at the Viking settlement known as L’Anse aux Meadows, reports SmithsonianMag.com. Each had been cut with a metal blade, a tool the Vikings had and the local indigenous people did not. Knowing that a major solar storm occurred in 993, the researchers looked in each specimen for a tree-ring that bore a distinct radiocarbon signal associated with such cosmic ray events. They then counted out the later growth rings, giving them the year—1021—the tree was felled. There’s much we still don’t know about L’Anse aux Meadows, including how long the Vikings lived there. “All we can really say,” says study co-author Michael Dee, “is that they were definitely there in that year.”

Bang, reports ScienceAlert.com, a discovery that could help explain how the universe switched on its lights. The first stars, known as Population III, came together in a sea of helium and hydrogen some 13.7 billion years ago, and so were exceptionally low in heavy elements. A Population III star has yet to be found, but a team at the University of Florence thinks it has discovered a direct descendant. AS0039 is located 290,000 light-years away in the Sculptor dwarf galaxy, where most of the stars are more than 10 billion years old. Using data from the European Southern Observatory’s Very Large Telescope in Chile, the researchers determined that AS0039 has the lowest metal content of any star outside the Milky Way and the lowest carbon content of any known star. This suggests that it contains elements of a Population III star that went hypernova, an explosion with 10 times more energy than a normal supernova. The study “provides crucial information about the energy of the first supernova explosions,” says co-author Stefania Salvadori, “and therefore on the first steps of the universe.”