23 | 15 amazing science facts that will blow your mind
34 |1. Babies have around 100 more bones than adults
36 |Babies have about 300 bones at birth, with cartilage between many of them. This extra flexibility helps 37 | them pass through the birth canal and also allows for rapid growth. With age, many of the bones fuse, 38 | leaving 206 bones that make up an average adult skeleton.
39 |2. The Eiffel Tower can be 15 cm taller during the summer
42 |When a substance is heated up, its particles move more and it takes up a larger volume – this is known as 43 | thermal expansion. Conversely, a drop in temperature causes it to contract again. The mercury level 44 | inside a thermometer, for example, rises and falls as the mercury’s volume changes with the ambient 45 | temperature. This effect is most dramatic in gases but occurs in liquids and solids such as iron too. 46 | For this reason, large structures such as bridges are built with expansion joints which allow them some 47 | leeway to expand and contract without causing any damage.
48 |3. 20% of Earth’s oxygen is produced by the Amazon rainforest
51 |Our atmosphere is made up of roughly 78 per cent nitrogen and 21 per cent oxygen, with various other 52 | gases present in small amounts. The vast majority of living organisms on Earth need oxygen to survive, 53 | converting it into carbon dioxide as they breathe. Thankfully, plants continually replenish our planet’s 54 | oxygen levels through photosynthesis. During this process, carbon dioxide and water are converted into 55 | energy, releasing oxygen as a by-product. Covering 5.5 million square kilometres (2.1 million square 56 | miles), the Amazon rainforest cycles a significant proportion of the Earth’s oxygen, absorbing large 57 | quantities of carbon dioxide at the same time.
58 |4. Some metals are so reactive that they explode on contact with water
61 |There are certain metals – including potassium, sodium, lithium, rubidium and caesium – that are so 62 | reactive that they oxidise (or tarnish) instantly when exposed to air. They can even produce explosions 63 | when dropped in water! All elements strive to be chemically stable – in other words, to have a full 64 | outer electron shell. To achieve this, metals tend to shed electrons. The alkali metals have only one 65 | electron on their outer shell, 66 | making them ultra-keen to pass on this unwanted passenger to another element via bonding. As a result 67 | they form compounds with other elements so readily that they don’t exist independently in nature.
68 |5. A teaspoonful of neutron star would weigh 6 billion tons
71 |A neutron star is the remnants of a massive star that has run out of fuel. The dying star explodes in a 72 | supernova while its core collapses in on itself due to gravity, forming a super-dense neutron star. 73 | Astronomers measure the mind-bogglingly large masses of stars or galaxies in solar masses, with one 74 | solar mass equal to the Sun’s mass (that is, 2 x 1030 kilograms/4.4 x 1030 pounds). Typical neutron 75 | stars have a mass of up to three solar masses, which is crammed into a sphere with a radius of 76 | approximately ten kilometres (6.2 miles) – 77 | resulting in some of the densest matter in the known universe.
78 |6. Hawaii moves 7.5cm closer to Alaska every year
81 |The Earth’s crust is split into gigantic pieces called tectonic plates. These plates are in constant 82 | motion, 83 | propelled by currents in the Earth’s upper mantle. Hot, less-dense rock rises before cooling and 84 | sinking, giving rise to circular convection currents which act like giant conveyor belts, slowly 85 | shifting the tectonic plates above them. Hawaii sits in the middle of the Pacific Plate, which is slowly 86 | drifting north-west towards the North American Plate, back to Alaska. The plates’ pace is comparable to 87 | the speed at which our fingernails grow.
88 |7. Chalk is made from trillions of microscopic plankton fossils
91 |Tiny single-celled algae called coccolithophores have lived in Earth’s oceans for 200 million years. 92 | Unlike any other marine plant, they surround themselves with minuscule plates of calcite (coccoliths). 93 | Just under 100 94 | million years ago, conditions were just right for coccolithophores to accumulate in a thick layer 95 | coating ocean floors in a white ooze. As further sediment built up on top, the pressure compressed the 96 | coccoliths to form rock, creating chalk deposits such as the white cliffs of Dover. Coccolithophores are 97 | just one of many prehistoric species that have been immortalised in fossil form, but how do we know how 98 | old they are? Over time, 99 | rock forms in horizontal layers, leaving older rocks at the bottom and younger rocks near the top. By 100 | studying the type of rock in which a fossil is found palaeontologists can roughly guess its age. Carbon 101 | dating estimates a fossil’s age more precisely, based on the rate of decay of radioactive elements such 102 | as carbon-14.
103 |8. In 2.3 billion years it will be too hot for life to exist on Earth
106 |Over the coming hundreds of millions of years, the Sun will continue to get progressively brighter and 107 | hotter. 108 | In just over 2 billion years, temperatures will be high enough to evaporate our oceans, making life on 109 | Earth impossible. Our planet will become a vast desert similar to Mars today. As it expands into a red 110 | giant in the following few billion years, scientists predict that the Sun will finally engulf Earth 111 | altogether, spelling the definite end for our planet.
112 |9. Polar bears are nearly undetectable by infrared cameras
115 |Thermal cameras detect the heat lost by a subject as infrared, but polar bears are experts at conserving 116 | heat. 117 | The bears keep warm due to a thick layer of blubber under the skin. Add to this a dense fur coat and 118 | they can endure the chilliest Arctic day.
119 |10. It takes 8 minutes, 19 seconds for light to travel from the Sun to the Earth
122 |In space, light travels at 300,000 kilometres (186,000 miles) per second. Even at this breakneck speed, 123 | covering the 150 million odd kilometres (93 million miles) between us and the Sun takes considerable 124 | time. And eight minutes is still very little compared to the five and a half hours it takes for the 125 | Sun’s light to reach Pluto.
126 |11. If you took out all the empty space in our atoms, the human race could fit in the volume of a sugar 129 | cube
130 |The atoms that make up the world around us seem solid but are in fact over 99.99999 per cent empty space. 131 | An atom consists of a tiny, dense nucleus surrounded by a cloud of electrons, spread over a 132 | proportionately vast area. This is because as well as being particles, electrons act like waves. 133 | Electrons can only exist where the crests and troughs of these waves add up correctly. And instead of 134 | existing in one point, each electron’s location is spread over a range of probabilities – an orbital. 135 | They thus occupy a huge amount of space.
136 |12. Stomach acid is strong enough to dissolve stainless steel
139 |Your stomach digests food thanks to highly corrosive hydrochloric acid with a pH of 2 to 3. This acid 140 | also attacks your stomach lining, which protects itself by secreting an alkali bicarbonate solution. The 141 | lining still needs to be replaced continually, and it entirely renews itself every four days.
142 |13. The Earth is a giant magnet
145 |Earth’s inner core is a sphere of solid iron, surrounded by liquid iron. Variations in temperature and 146 | density create currents in this iron, which in turn produce electrical currents. Lined up by the Earth’s 147 | spin, these currents combine to create a magnetic field, used by compass needles worldwide.
148 |14. Venus is the only planet to spin clockwise
151 |Our Solar System started off as a swirling cloud of dust and gas which eventually collapsed into a 152 | spinning disc with the Sun at its centre. Because of this common origin, all the planets move around the 153 | Sun in the same direction and on roughly the same plane. They also all spin in the same direction 154 | (counterclockwise if observed from ‘above’) – except Uranus and Venus. Uranus spins on its side, while 155 | Venus defiantly spins in the complete opposite direction. The most likely cause of these planetary 156 | oddballs are gigantic asteroids which knocked them off course in the distant past.
157 |15. A flea can accelerate faster than the Space Shuttle
160 |A jumping flea reaches dizzying heights of about eight centimetres (three inches) in a millisecond. 161 | Acceleration is the change in speed of an object over time, often measured in ‘g’s, with one g equal to 162 | the acceleration caused by gravity on Earth (9.8 metres/32.2 feet per square second). Fleas experience 163 | 100 g, while the Space Shuttle peaked at around 5 g. The flea’s secret is a stretchy rubber-like protein 164 | which allows it to store and release energy like a spring.
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