1. Babies have around 100 more bones than adults
Babies
have about 300 bones at birth, with cartilage between many of them.
This extra flexibility helps them pass through the birth canal and also
allows for rapid growth. With age, many of the bones fuse, leaving 206
bones that make up an average adult skeleton.
2. The Eiffel Tower can be 15 cm taller during the summer
When a substance is heated up, its
particles move more and it takes up a larger volume – this is known as
thermal expansion. Conversely, a drop in temperature causes it to
contract again. The mercury level inside a thermometer, for example,
rises and falls as the mercury’s volume changes with the ambient
temperature. This effect is most dramatic in gases but occurs in liquids
and solids such as iron too. For this reason, large structures such as
bridges are built with expansion joints which allow them some leeway to
expand and contract without causing any damage.
3. 20% of Earth’s oxygen is produced by the Amazon rainforest
Our atmosphere is made up of roughly 78
per cent nitrogen and 21 per cent oxygen, with various other gases
present in small amounts. The vast majority of living organisms
on Earth need oxygen to survive, converting it into carbon dioxide as
they breathe. Thankfully, plants continually replenish our planet’s
oxygen levels through photosynthesis. During this process, carbon
dioxide and water are converted into energy, releasing oxygen as a
by-product. Covering 5.5 million square kilometres (2.1 million square
miles), the Amazon rainforest cycles a significant proportion of the
Earth’s oxygen, absorbing large quantities of carbon dioxide at the same
time.
4. Some metals are so reactive that they explode on contact with water
There are certain metals – including
potassium, sodium, lithium, rubidium and caesium – that are so reactive
that they oxidise (or tarnish) instantly when exposed to air. They can
even produce explosions when dropped in water! All elements strive to be
chemically stable – in other words, to have a full outer electron
shell. To achieve this, metals tend to shed electrons. The alkali metals
have only one electron on their outer shell, making them ultra-keen to
pass on this unwanted passenger to another element via bonding. As a
result they form compounds with other elements so readily that they
don’t exist independently in nature.
5. A teaspoonful of neutron star would weigh 6 billion tons
A neutron star
is the remnants of a massive star that has run out of fuel. The dying
star explodes in a supernova while its core collapses in on itself due
to gravity, forming a super-dense neutron star. Astronomers measure the
mind-bogglingly large masses of stars or galaxies in solar masses, with
one solar mass equal to the Sun’s mass (that is, 2 x 1030 kilograms/4.4 x
1030 pounds). Typical neutron stars have a mass of up to three solar
masses, which is crammed into a sphere with a radius of approximately
ten kilometres (6.2 miles) – resulting in some of the densest matter in
the known universe.
6. Hawaii moves 7.5cm closer to Alaska every year
The Earth’s crust
is split into gigantic pieces called tectonic plates. These plates are
in constant motion, propelled by currents in the Earth’s upper mantle.
Hot, less-dense rock rises before cooling and sinking, giving rise to
circular convection currents which act like giant conveyor belts, slowly
shifting the tectonic plates above them. Hawaii sits in the middle of
the Pacific Plate, which is slowly drifting north-west towards the North
American Plate, back to Alaska. The plates’ pace is comparable to the
speed at which our fingernails grow.
7. Chalk is made from trillions of microscopic plankton fossils
Tiny single-celled algae
called coccolithophores have lived in Earth’s oceans for 200 million
years. Unlike any other marine plant, they surround themselves with
minuscule plates of calcite (coccoliths). Just under 100 million years
ago, conditions were just right for coccolithophores to accumulate in a
thick layer coating ocean floors in a white ooze. As further sediment
built up on top, the pressure compressed the coccoliths to form rock,
creating chalk deposits such as the white cliffs of Dover.
Coccolithophores are just one of many prehistoric species that have been
immortalised in fossil form, but how do we know how old they are? Over
time, rock forms in horizontal layers, leaving older rocks at the bottom
and younger rocks near the top. By studying the type of rock in which a
fossil is found palaeontologists can roughly guess its age. Carbon dating estimates a fossil’s age more precisely, based on the rate of decay of radioactive elements such as carbon-14.
8. In 2.3 billion years it will be too hot for life to exist on Earth
Over the coming hundreds of millions of years, the Sun
will continue to get progressively brighter and hotter. In just over 2
billion years, temperatures will be high enough to evaporate our oceans,
making life on Earth impossible. Our planet will become a vast desert
similar to Mars today. As it expands into a red giant in the following
few billion years, scientists predict that the Sun will finally engulf
Earth altogether, spelling the definite end for our planet.
9. Polar bears are nearly undetectable by infrared cameras
Thermal cameras detect the heat lost by
a subject as infrared, but polar bears are experts at conserving heat.
The bears keep warm due to a thick layer of blubber under the skin. Add
to this a dense fur coat and they can endure the chilliest Arctic day.
10. It takes 8 minutes, 19 seconds for light to travel from the Sun to the Earth
In space, light travels at 300,000
kilometres (186,000 miles) per second. Even at this breakneck speed,
covering the 150 million odd kilometres (93 million miles) between us
and the Sun takes considerable time. And eight minutes is still very
little compared to the five and a half hours it takes for the Sun’s
light to reach Pluto.
11. If you took out all the empty space in our atoms, the human race could fit in the volume of a sugar cube
The atoms that make up the world around
us seem solid but are in fact over 99.99999 per cent empty space. An
atom consists of a tiny, dense nucleus surrounded by a cloud of
electrons, spread over a proportionately vast area. This is because as
well as being particles, electrons act like waves. Electrons can only
exist where the crests and troughs of these waves add up correctly. And
instead of existing in one point, each electron’s location is spread
over a range of probabilities – an orbital. They thus occupy a huge
amount of space.
12. Stomach acid is strong enough to dissolve stainless steel
Your stomach digests food thanks to
highly corrosive hydrochloric acid with a pH of 2 to 3. This acid also
attacks your stomach lining, which protects itself by secreting an
alkali bicarbonate solution. The lining still needs to be replaced
continually, and it entirely renews itself every four days.
13. The Earth is a giant magnet
Earth’s inner core is a sphere of solid
iron, surrounded by liquid iron. Variations in temperature and density
create currents in this iron, which in turn produce electrical currents.
Lined up by the Earth’s spin, these currents combine to create a
magnetic field, used by compass needles worldwide.
14. Venus is the only planet to spin clockwise
Our Solar System started off as a
swirling cloud of dust and gas which eventually collapsed into a
spinning disc with the Sun at its centre. Because of this common origin,
all the planets move around the Sun in the same direction and on
roughly the same plane. They also all spin in the same direction
(counterclockwise if observed from ‘above’) – except Uranus and Venus.
Uranus spins on its side, while Venus defiantly spins in the complete
opposite direction. The most likely cause of these planetary oddballs
are gigantic asteroids which knocked them off course in the distant
past.
15. A flea can accelerate faster than the Space Shuttle
A jumping flea reaches dizzying heights
of about eight centimetres (three inches) in a millisecond.
Acceleration is the change in speed of an object over time, often
measured in ‘g’s, with one g equal to the acceleration caused by gravity
on Earth (9.8 metres/32.2 feet per square second). Fleas experience 100
g, while the Space Shuttle peaked at around 5 g. The flea’s secret is a
stretchy rubber-like protein which allows it to store and release
energy like a spring.
