Revelations of Repeat Photos

For 50 years, the U.S. Geological Survey has been building an archive of old photos of desert landscapes and new photos of them. Check out the fascinating results.

Taking photos from the same vantage point years apart has long been used to study landscape. The technique got its start as a way to document the retreat of European glaciers. For 50 years, the U.S. Geological Survey has been building an archive old photos of desert landscapes and revisiting the sites to take new photos. The result is the largest collection of repeat photography in the world. ...We have a few of the most interesting repeat photographs in this gallery that show changes such as the retreat of glaciers, the birth and death of cactus forests, the excavation of ruins and the shifting of a river channel.

3D printing might save your life one day. It's transforming medicine and health care.

What can 3D printing do for medicine? The "sky is the limit," says Northwell Health researcher Dr. Todd Goldstein.

Northwell Health
Sponsored by Northwell Health
  • Medical professionals are currently using 3D printers to create prosthetics and patient-specific organ models that doctors can use to prepare for surgery.
  • Eventually, scientists hope to print patient-specific organs that can be transplanted safely into the human body.
  • Northwell Health, New York State's largest health care provider, is pioneering 3D printing in medicine in three key ways.
Keep reading Show less

Permafrost is melting 70 years earlier than expected in Arctic Canada

It's a "canary in the coalmine," said one climate scientist.


MARK RALSTON/Contributor
Surprising Science
  • A team of researchers discovered that permafrost in Northern Canada is melting at unusually fast rates.
  • This could causes dangerous and costly erosion, and it's likely speeding up climate change because thawing permafrost releases heat-trapping gasses into the atmosphere.
  • This week, Canada's House of Commons declared a national climate emergency.
Keep reading Show less

Has a black hole made of sound confirmed Hawking radiation?

One of Stephen Hawking's predictions seems to have been borne out in a man-made "black hole".

Image source: NASA/JPL-Caltech
Surprising Science
  • Stephen Hawking predicted virtual particles splitting in two from the gravitational pull of black holes.
  • Black holes, he also said, would eventually evaporate due to the absorption of negatively charged virtual particles.
  • A scientist has built a black hole analogue based on sound instead of light.
Keep reading Show less

Watch scientists melt a satellite part to save us from space junk

Not every part of a satellite burns up in reentry. Considering the growing number of satellites in orbital space, that's a big problem.

Technology & Innovation
  • Earth's orbital space is getting more crowded by the day.
  • The more satellites and space junk we put into orbit, the greater a risk that there could be a collision.
  • Not all materials burn up during reentry; that's why scientists need to stress test satellite parts to ensure that they won't become deadly falling objects.
Keep reading Show less