Did you know? — archive

Every day's set of facts, newest first.

Today

01
Despite being the largest planet, Jupiter spins so fast that one full day there lasts under 10 hours.
02
The Milky Way and the neighbouring Andromeda galaxy are on course to collide and merge in about 4.5 billion years.
03
Saturn's rings are made almost entirely of ice, with water ice making up more than 90% of their material.
04
Pluto takes about 248 Earth years to complete one full orbit around the Sun.
05
The core of the Sun reaches a temperature of about 15 million degrees Celsius.
06
Some spider silk is stronger than steel of the same thickness, yet far lighter and more elastic.
07
A human baby is born with about 300 bones, but many fuse together as it grows, leaving an adult with only 206.
08
Butterflies do not taste with their mouths — they have taste receptors on their feet that let them identify plants the moment they land.
09
Honeybees perform a special dance inside the hive to tell other bees the exact direction and distance of a food source.
10
Cats lack the taste receptor for sweetness, which is why they show no interest in sugary food.
11
The platypus can detect the tiny electrical signals given off by its prey's muscles, using electroreceptors in its bill.
12
Chameleons change colour mainly to signal mood, temperature and social status to other chameleons, not primarily to hide from predators.
13
Giant sequoia trees can live for more than 3,000 years, making them among the longest-lived organisms on Earth.
14
Absolute zero, the coldest temperature theoretically possible, is -273.15 degrees Celsius.
15
Light travels at about 300,000 kilometers per second in a vacuum, the fastest speed anything can travel in the universe.
16
Breathing helium makes your voice sound higher because sound travels almost three times faster through helium than through normal air.
17
A stretched rubber band actually gets slightly warmer, and cools down again when you let it snap back.
18
Glass is a rigid, amorphous solid, not a slow-flowing liquid, despite the old popular myth about old windowpanes.
19
The Amazon River discharges more freshwater into the ocean than the world's next seven largest rivers combined.
20
The average person blinks about 15 to 20 times every minute, more than is needed just to keep the eyes wet.
21
The Dead Sea's water is about 34% salt, nearly ten times saltier than a typical ocean.
22
Lightning strikes somewhere on Earth roughly 8 million times a day.
23
Earth's magnetic poles have completely reversed many times over the planet's history, with north and south swapping places.
24
Earth's inner core is solid iron even though its temperature is close to the surface temperature of the Sun, because the immense pressure there keeps it from melting.
25
The first email was sent in 1971 by engineer Ray Tomlinson, who also popularised the @ symbol in email addresses.
26
The QWERTY keyboard layout still used today was designed in the 1870s for mechanical typewriters.
27
The @ symbol was already in use in trade and accounting records centuries before email adopted it as the address symbol.
28
The human heart pumps roughly 2,000 gallons (about 7,500 liters) of blood through the body every day.
29
Fingernails grow faster than toenails, roughly three to four times the speed.
30
The adult human body contains about 37 trillion cells.

Did you know? — archive

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