SKY GLOW This panoramic view of the night sky from Meteor Crater in Arizona shows how light from Winslow, Phoenix and Flagstaff (left to right, starting at 90°) makes it harder to see the stars.
Dan Duriscoe/National Park Service
SPIKES OUT Tiny lake dwellers known as water fleas (Daphniapulex shown) raise spiky defenses when sensing predators nearby. But high levels of carbon dioxide in lake waters may dull their senses, leaving the critters open to attack.
TURTLE TROUBLE Green sea turtle populations in parts of the Great Barrier Reef are becoming increasingly female because their eggs are being incubated at higher temperatures due to warming ocean waters.