Dark matter is believed to make up more than 80 percent of all matter in the universe, but what it actually is remains a mystery. Now, astronomers have found something that gives us a major clue. In a ...

Dark matter is believed to make up more than 80 percent of all matter in the universe, but what it actually is remains a mystery. Now, astronomers have found something that gives us a major clue. This ...

Chichén Itzá, "the mouth of the well of the Itzás," was likely the most important city in the Yucatán from the 10th to the 12th centuries. Evidence indicates that the site was first settled as early ...