All facts — Page 61

The parrotfish sleeps inside a mucus cocoon that it produces every night.

Before sleeping, the parrotfish secretes a transparent mucus envelope from glands in its skin. The cocoon protects it…

There are ants that explode to defend the colony.

The ant Colobopsis explodens, discovered in Southeast Asia, has glands full of a toxic substance. When threatened, it…

The mimic octopus can imitate more than 15 different animals, including the lionfish and the sea snake.

The mimic octopus, which lives in shallow waters of Southeast Asia, changes colour, shape and behaviour to imitate…

The emperor penguin can dive more than 500 metres and stay submerged for more than 20 minutes.

The emperor penguin is the bird that dives deepest and for the longest time. It can reduce its heart rate and store…

The inner surface of human lungs, if stretched, would cover a tennis court.

The lungs contain about 300 million alveoli, small sacs where gas exchange takes place. If all were opened and…

The cashew nut grows attached to a fruit, and the part we eat is the seed.

The cashew is a fruit that develops at the tip of a fleshy stalk called a pseudofruit. The nut, which is the seed…

Capsaicin in chilli peppers is not a taste, it activates pain and heat receptors.

Chilli does not have a spicy taste in the traditional sense. Capsaicin binds to TRPV1 receptors, the same ones that…

The Caspian Sea is the largest lake in the world, larger than Germany.

Despite its name, the Caspian Sea is a lake, as it has no connection to the ocean. With about 371,000 square…

In Hammerfest, Norway, the sun does not set for about 76 consecutive days in summer.

Hammerfest is above the Arctic Circle. In summer, the sun remains visible 24 hours a day for more than two months. In…

The Sahara Desert was once green and had giant lakes about 10,000 years ago.

About 10,000 years ago, the Sahara was a savannah with lakes, rivers and abundant vegetation. The period, known as…

The Library of Alexandria was probably not destroyed in a single fire.

Contrary to popular belief, the Library of Alexandria did not disappear in a single fire. Historians believe it was…

The United States Declaration of Independence was voted on 2 July 1776, but it is celebrated on 4 July.

The Continental Congress voted in favour of independence on 2 July 1776. The written declaration was approved on 4…

The road network of the Roman Empire was over 400,000 kilometres long.

At the height of the Empire, the Romans built a network of more than 400,000 kilometres of roads, of which about…

The smell of rain on dry ground comes from soil bacteria.

The characteristic smell of rain, called petrichor, is caused by a molecule called geosmin, produced by soil…

Volcanic eruptions can produce lightning, called dirty thunderstorms.

During eruptions, ash and rock fragments collide and generate electrical charges. The result is volcanic lightning…

Giant sequoias can live for more than 3,000 years.

Giant sequoias in California are the oldest trees in the world. Some exceed 3,000 years of age. Their thick bark…

The speed of light in a vacuum is exactly 299,792,458 metres per second.

Since 1983, the speed of light in a vacuum has been a constant defined by convention. The exact value is 299,792,458…

A lightning bolt is about five times hotter than the surface of the Sun.

The temperature of a lightning bolt can reach 30,000 kelvin, while the Sun's surface is around 5,500 kelvin. The heat…

There are more ways to shuffle a 52-card deck than there are atoms on Earth.

The number of possible combinations of a 52-card deck is 52 factorial, a number with 68 digits. It is much larger…

Saturn has a hexagon-shaped storm at its north pole.

At Saturn's north pole there is a hexagon-shaped jet stream about 30,000 kilometres wide. The phenomenon was first…

Astronauts describe the smell of space as hot metal and burnt meat.

When returning to the space station after a spacewalk, astronauts report a strong smell of hot metal and burnt meat…

The Oort Cloud is a distant region of the Solar System with billions of comets.

The Oort Cloud is a spherical shell of icy bodies believed to exist at the edges of the Solar System, up to 100,000…

IBM's first hard drive, in 1956, weighed about a tonne and stored 5 megabytes.

The IBM 305 RAMAC, from 1956, was the first computer with a hard drive. The drive weighed about a tonne and stored…

The first video published on YouTube is called Me at the zoo.

The first YouTube video, published on 23 April 2005, is called Me at the zoo and shows Jawed Karim, one of the…