What's the biggest magnet ever? Find out on this Moment of Science.
Millions of monarch butterflies fly southwest from eastern Canada and the United States down to Mexico each autumn; then millions more fly back to the northeast in the spring.The one-way trip is as long as 2500 miles for some of these creatures.
Although dissection remains a staple of medical training, over the years we have developed less invasive ways of peering inside the body. One of the most revolutionary and successful is MRI, or magnetic resonance imaging.