Earth's first life forms consisted of simple prokaryotic cells. Over time, these evolved into the more complex eukaryotic cells with nuclei.
Polonium was a critical ingredient in the first atomic bomb and it's a suspected poison in more than one high-profile death.
Hippocrates was a physician who lived in ancient Greece. He was the first to teach that illness had a natural cause rather than being the wrath of the gods.
Greenland is the biggest island on Earth, and it's covered by a thick ice sheet. Scientists are growing extremely concerned that global warming is melting the ice too quickly.
Does adding sugar, aspiring or vinegar to the water keep your Christmas tree fresher longer? Try this experiment to find out.
The Mississippi River touches 31 U.S. states and two Canadian provinces and is one of the largest rivers in the world.
The Yangtze River is the longest river in Asia. It is approximately 3,915 miles (6,300 kilometers) long, the third longest river in the world.
The Amazon River is a massive, intricate water system. It is by far the mightiest river on Earth in terms of volume and width.
The Nile River is considered the longest river in the world, but its actual length is a matter of debate.
Microbursts, also called downbursts, are powerful, localized columns of wind. They can cause just as much damage as a tornado.
Arsenic is a naturally occurring element with a reputation as "king of poisons" as well as the "poison of kings."