A woman looking out a train window into the sunset with vitamin d pills approaching

How Does the Body Make Vitamin D from Sunlight?

A Curious Reader asks: How exactly does exposure to sunlight cause the the human body to synthesize Vitamin D3?
A giant squid

Why Deep-Sea Creatures Get Weirdly Giant

A giant squid sighting has us wondering all over again: how on earth do deep-sea creatures get so large?
The Mars Curiosity Rover

The Meaning of Methane on Mars

Curiosity rover's recent report of methane on Mars isn't the first time the gas has been indicated. Does it necessarily mean that Mars harbors life?
A bark scorpion in Arizona

How Does a Scorpion Decide When to Sting?

There are actually two decisions to make: whether to sting at all and whether to use prevenom or full venom.
Climbers ascending Mount Everest

Mount Everest’s Death Zone

The zone above 8,000 meters is known among mountaineers as the “Death Zone.” Why do most deaths in the high mountains occur at these extreme heights?
A carnival cruise ship

The High Environmental Costs of Cruise Ships

Cruise ships pose many environmental concerns, from waste disposal to toxic paint to the creation of noise that can harm marine life.
Blue viper snake eating a frog, Indonesia

How Snakes Swallow

A snake’s ability to swallow enormous prey has long been a source of fascination, but the common explanation that they dislocate their jaws is a myth.
Eastern phoebe nest with one brown-headed cowbird egg

The Sky’s Creepiest Parasites

Are you a bird? Is your chick acting weird? You might be victim of a brood parasite.
A tornado in a field

Why Tornadoes Are So Difficult to Predict

Scientists and weather forecasters have been trying to understand tornadoes for over 100 years, but the average advanced warning is still only 14 minutes.
A constellation of satellites

Losing the Night Sky

Does an increase in satellites mean we soon won't be able to see the stars?