Researchers are using sound to study Pando, the world's largest tree.
Déjà vu, the feeling of having experienced something before, is very common, but why does it happen?
The government is investigating hundreds of military UFO reports, but only a small fraction are truly "anomalous."
A study suggests that more U.S. teens with obesity are getting weight-loss surgeries, in line with official guidelines from the American Academy of Pediatrics.