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A red-eyed tree frog clutches a branch in a rainforest in Australia. Frogs are challenged by the climate crisis, pollution, and a deadly fungus—exacerbated by Europe's demand for their legs. Conservationists say the EU should do more to help regulate the trade and protect species.

Video Clip SS272144 (Phases of the Far Side of the Moon)

Animation showing a time-lapse wide-angle view of the phases of the far side of the Moon, with the Earth rotating behind it. 

The Earth rotates on its own axis in 24 hours. The Moon orbits the spinning Earth in approximately 27.3 days, but because the Moon rotates upon its own axis once during the same period, it always presents the same side to the Earth. 

See More From The Lunar Reconnaissance Orbiter

As the Moon orbits the Earth, the area of its surface lit by the Sun changes, resulting in the lunar phases. The animation was created using data from NASA's Lunar Reconnaissance Orbiter.

Silk moth caterpillar at 31:1 magnification.

This colorized scanning electron micrograph shows the mouth parts of a brown dog tick, one of the most important disease vectors in dogs worldwide. Ticks that carry human pathogens are spreading in the U.S., triggering an increase in tick-borne diseases, including some that are difficult to diagnose and treat.

Video Clip SS283010 (White Blood Cells Leaving The Blood Stream)

Time-lapse light microscopy footage of white blood cells (leucocytes) migrating to the surrounding tissue from the bloodstream. 

This is known as extravasation (or diapedesis) and is a response by the body to tissue damage or infection. The white blood cells are part of the innate (non-specific) immune system response.

The immune system can distinguish between normal, healthy cells and unhealthy cells by recognizing a variety of "danger" cues called danger-associated molecular patterns (DAMPs).

Infectious microbes such as viruses and bacteria release another set of signals recognized by the immune system called pathogen-associated molecular patterns (PAMPs).

The Dinosaur-Killing Asteroid Acidified the Ocean in a Flash

by Lucas Joel / NY Times

What happened to the dinosaurs when an asteroid about six miles wide struck Earth some 66 million years ago in what is today Mexico is well known: It wiped them out. But the exact fate of our planet’s diverse ocean dwellers at the time,  shelly ammonites, giant mosasaurs and other sea creatures, has not been as well understood.

New research now makes the case that the same incident that helped bring an end to the reign of the dinosaurs also acidified the planet’s oceans, disrupted the food chain that sustained life underwater and resulted in a mass extinction. The study, published Monday in Proceedings of the National Academy of Sciences, aims to shore up the hypothesis that the Chicxulub event’s destruction of marine life, the result of sulfur-rich rocks depositing acid rain into the oceans, was just as severe as the fire and fury it brought to land.

“It’s flash acidification, and it transformed ecosystems for millions of years,” said Noah Planavsky, a biogeochemist at Yale and one of the study’s authors. “We were shocked that we actually found this.”

The impact of the Chicxulub asteroid, so named for the crater it carved out around the Gulf of Mexico, sent columns of rock into Earth’s atmosphere, incinerated the planet’s forests and drove tsunamis far across the oceans. But the connection between the crash and the marine extinction has been less solid.

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