scary

Pictured above are the orbits of the over 1,000 known Potentially Hazardous Asteroids (PHAs). These documented tumbling boulders of rock and ice are over 140 meters across and will pass within 7.5 million kilometers of Earth -- about 20 times the distance to the Moon. Although none of them will strike the Earth in the next 100 years -- not all PHAs have been discovered, and past 100 years, many orbits become hard to predict.

Here's another reason never to go swimming:

This rare form of parasitic meningitis—primary amebic meningoencephalitis (PAM)—is caused by an amoeba called Naegleria fowleri. That microscopic amoeba—part of the class of life called protozoans—is a naturally occurring organism that normally feeds on bacteria and tends to live in the sedimentary layer of warm lakes and ponds.