World's Tallest Trees at Risk

TECH SPACE HUMAN EARTH HISTORY ANIMALS ADVENTURE VIDEO View Online World's Tallest Trees at Risk With a nod to Arbor Day, here's a rundown of some of the Earth's biggest tree species -- and what ails them. READ MORE One of Titan's Strange Seas is Pure Methane Titan -- the only other body in the solar system besides Earth where liquids pool on the surface -- has a sea of pure methane. READ MORE WATCH VIDEO: If Aliens Didn't Make Saturn's Hexagon, What Did?  A strange geometric shape is observed on a faraway world. Haven't we seen this movie before? Lizards Dream (And So Did Dinosaurs) Sleep patterns like REM evolved in a common animal ancestor more than 300 million years ago. READ MORE WATCH VIDEO: Can You Die From A Lack Of Sleep? DNews tries to find the point where no sleep equals death. Do Massages Really Help Muscles Heal? Therapeutic massage has long been touted as a way to bring strained muscles back to life. Does science back that up? WATCH Follow Discovery News on Facebook! Get your sci-tech headlines all day on Twitter too! At Discovery Communications, we value your privacy. If you would like to be removed from future communications like this, please click here. Privacy Policy Discovery Communications, LLC One Discovery Place Silver Spring, MD 20910 © Copyright 2016 Discovery Communications, LLC