An Olympic gold medal is almost 99% silver.

The first-place medal is actually 550 grams of silver covered with a thin layer of gold (6 grams)! A silver medal is far more authentic - 509 grams of silver and 41 grams of copper. The bronze medal is composed of mostly copper, with some zinc and tin mixed in. And approximately how much are all these precious medals worth, you ask? The gold - $494, the silver - $260, and the bronze...$3!

A man survived both the Hiroshima and Nagasaki atomic bombs.

Unfortunately, this remarkable individual passed away earlier this year at the age of 93. Tsutomu Yamaguchi is the only individual to be recognized as having survived both atomic bombs during World War II. Back in 1945, Yamaguchi was on a business trip to Hiroshima when the first bomb dropped on August 6th. The blast caused him to go blind and deaf temporarily, and had serious burns across his body.

He returned home to Nagasaki three days later to a second atomic bomb less than 2 miles from his house! The explosions caused him to go completely deaf in his left ear. In later years, he suffered from complications such as leukemia, cataracts, and other bomb and radiation-related illnesses. Yamaguchi was one of 200,000 Japanese citizens recognized as having been affected by either of the bombs.

Before working on Avatar, actor Sam Worthington was living in his car!

He was already an actor in Australia at the time, but Worthington was living in his car prior to meeting James Cameron and landing the Avatar role. Worthington also has worked in the past as a bricklayer. Definitely an unusual background for someone in one of the most successful movies of all time.

At only 1 DEGREE above absolute zero, the Boomerang Nebula is the coldest place in the known universe.

Absolute Zero is a theoretical temperature that cannot possibly be reached in our universe. It's the equivalent of −273.15°C or −459.67°F.

The Boomerang Nebula is a cloud of dust and gas expanding from an old star that is collapsing in on itself. Scientists approximate its extremely low temperature based on the fact that it is losing mass at 100 times the rate of other expanding nebulae.

Every year, a rumor goes around the internet that some time in August will be a once in a lifetime opportunity to see Mars, because it will look as bi

Why do we see this rumor every year, often in the same time of the year?

August 27, 2003 was when Mars was the closest to our planet that it has ever been in over 50,000 years (35 million miles away, about 144 times as far away as the mooon).

At that time, Mars appeared to be 6 times larger than it normally does. At the time it was an exciting event, as long as you had a telescope. To the naked eye, Mars was still just a tiny dot in the sky.

At the time, chain emails went around that overstated the event, claiming that Mars would be within only a few miles of us, that it would be next to the moon, or that it would look like we had two moons in the sky. These emails still show up every year, even though the event happened almost 7 years ago.

Dolphins don't breathe automatically - they breathe when they tell themselves to breathe

When dolphins sleep, they lie on their side with their blowhole above the water surface. They sleep with only half of their brain at time, and they take turns sleeping with different sides of its brain. The other half stays awake so the dolphin remembers to breathe. This also means that dolphins cannot receive anesthetics because they will stop breathing.

Our sun is so big that 1 million earths could fit inside of it. On the other hand, the largest star known to man is called VY Canis Majoris which could house 9,261,000,000 Suns

If VY Canis Majoris were put in our sun's place it would extend past Saturn. VY Canis Majoris can also fit 7×10^15 Earths inside of it (that's 7 with 15 zeros after it.)

In the 1950s, the United States planned to drop a nuclear bomb on the moon

At the time, the US was lagging behind the Soviet Union in the space race (For example, they sent a man into space before the US did.) Exploding a nuclear weapon on the moon was a way to one-up the Soviet Union. They planned on nuking the moon as a PR stunt, and they wanted to make sure the explosion could be seen from Earth!

This was part of a top-secret Air Force project, "Project A119" which was called "A Study of Lunar Research Flights". Details of the 1958 plan were made public in 2000 by Dr. Leonard Reiffel, the physicist who ran the project. He had worked on the project with famous astronomer Carl Sagan.
Sagan may have also disclosed some of this top-secret information when he applied for the prestigious Miller Institute graduate fellowship to Berkeley. At the time, Sagan thought that a nuclear explosion could reveal whether there was life on the moon.
The explosion likely would have ruined the face of the "man on the moon". Thankfully, years later they decided to send Neil Armstrong to the moon, and not a nuclear bomb.

Squirrels plant trees. ON ACCIDENT.

Despite the fact that they've yet to learn to look both ways before crossing the street, squirrels are actually pretty smart. They have an elaborate system for preserving their food. This includes burying nuts and acorns underground so that they can get to them much later. Sometimes if they don't get around to eating their buried treasure, the nuts grow into trees. This is actually really important because it allows for trees to grow farther away from other trees so that forests can spread.

Squirrels know exactly how well the nuts and acorns they find can stay preserved, which means that when they find nuts they know which ones to bury at which time and where. They also have a process to make acorns last longer: taking out the embryo!

They're also really sneaky. Give a squirrel some nuts and he'll dig several "dummy" holes for each actual nut that he buries. This throws off other animals watching them who would try to steal their food. Sometimes they even pretend to bury nuts to send their competition on a wild goose chase.

The Slave-Maker ant is a species of ants that enslaves other ants!

The whole process is really complex. The slave-maker queen fakes her own death and gets carried to the host colony. She then wakes up, and then kills and impersonates the queen. The fake queen will then start making her own offspring, who eventually take over the nest and enslave the previous inhabitants. The slave ants will unknowingly feed the fake queen and its offspring, not realizing that they are impostors.