100 Fun Facts About Science

What is the chemical symbol for gold?

Au comes from the Latin 'aurum'; gold is so unreactive that it is one of the few metals found in nature as nuggets of pure metal.

Which planet is the only one less dense than water?

Saturn has a mean density of about 0.69 g/cm³, the only planet below water's 1 g/cm³, so it would float in a large enough ocean; Jupiter is roughly twice as dense.

Which organelle is nicknamed the 'powerhouse of the cell'?

Mitochondria, which carry their own small circular genome, inherited only from your mother, because they were once free-living bacteria that moved in. Philip Siekevitz coined the nickname in Scientific American.

What is the speed of light in a vacuum, approximately?

The speed of light in a vacuum is approximately 299,792 kilometers per second (about 300,000 km/s). It is the universal speed limit according to Einstein's theory of special relativity.

Which scientist is credited with developing the theory of general relativity?

Albert Einstein published general relativity in 1915, and Arthur Eddington's 1919 eclipse expedition confirmed it by measuring starlight bending around the Sun by the amount he predicted.

What is the hardest natural substance on Earth?

Diamond, which is hard but not tough: hardness is resistance to scratching, and a hammer blow along a cleavage plane will split it. It is pure carbon, the same stuff as pencil graphite, arranged differently.

What gas makes up approximately 78% of Earth's atmosphere?

Nitrogen makes up about 78% of dry air, with oxygen near 21%; argon, not carbon dioxide, is the third most plentiful gas at just under 1%.

What is the largest organ in the human body?

Skin accounts for roughly 16% of body mass and is constantly renewed, shedding its outer layer every few weeks.

Which element has the atomic number 1?

Hydrogen, the lightest and simplest atom, and the fuel the Sun burns by fusing it into helium. Nearly everything heavier was cooked inside stars.

What phenomenon causes the Northern Lights?

Excited oxygen produces the familiar green glow, while nitrogen adds blues and purples; the same process over the South Pole is the aurora australis.

What is the chemical formula for table salt?

NaCl, sodium chloride: sodium explodes in water and chlorine was a First World War weapon, yet bonded together they season dinner. The 'Na' comes from the Latin natrium.

Which blood type is considered the universal donor?

Only about 7% of people are O negative, so blood banks prize it for emergencies when there is no time to type a patient.

What is the most abundant protein in the human body?

Collagen makes up roughly a quarter to a third of all the body's protein, forming the fibrous scaffolding of skin, tendon, bone and cartilage; its triple-helix structure gives it tensile strength.

Who discovered penicillin?

Fleming noticed the mould in 1928 after returning from holiday to find it had killed the bacteria on a neglected culture plate.

What is the unit of electrical resistance?

Its symbol is the Greek capital omega, and its inverse, the unit of conductance, was cheekily named the 'mho'.

What type of rock is formed from cooled lava or magma?

Igneous rocks form when molten rock (magma or lava) cools and solidifies. Examples include granite (formed underground) and basalt (formed from surface lava flows).

What is the closest star to Earth after the Sun?

Proxima Centauri is about 4.24 light-years from Earth. It is a small red dwarf star in the Alpha Centauri star system and has at least two confirmed exoplanets.

Which vitamin is produced when human skin is exposed to sunlight?

Ultraviolet B (UVB) radiation from sunlight triggers vitamin D synthesis in the skin. Vitamin D is essential for calcium absorption and bone health.

What is the process by which plants convert sunlight into energy?

Photosynthesis takes place in chloroplasts, where light energy drives the reactions that build sugars; the gas plants release in the process is, chemically, their waste. Every breath you take is a plant's rubbish.

What is the Heisenberg Uncertainty Principle about?

Werner Heisenberg showed in 1927 that a particle's position and momentum cannot both be known exactly; the product of their uncertainties has a floor set by Planck's constant, a property of nature rather than of instruments.

What is the pH of pure water at room temperature?

Pure water at 25 °C has a pH of 7, the neutral point, though it drifts slightly below 7 as water warms; the scale itself was devised by Danish chemist Søren Sørensen in 1909.

Which planet is known as the Red Planet?

Mars, which is rusty because its iron-rich dust oxidised long ago, and it also hosts the tallest volcano in the Solar System, Olympus Mons, about two and a half times the height of Everest.

What is the function of white blood cells?

Fight infections, which is why a high count is a sign the body is at war. Red cells outnumber them about 700 to one, and platelets, not white cells, do the clotting.

What force keeps planets in orbit around the Sun?

Gravity, and an orbit really is a fall: the planet drops toward the Sun but its sideways speed carries it past, over and over. Newton worked this out with a cannonball fired ever faster from a mountaintop.

What is the most common element in the Earth's crust?

Nearly half the crust's mass is oxygen locked up in silicate and oxide minerals; silicon comes second at roughly 28%.

Who proposed the heliocentric model of the solar system?

Nicolaus Copernicus published his heliocentric model in 1543, proposing that the Earth and other planets revolve around the Sun rather than everything orbiting Earth.

What is the smallest unit of matter that retains the properties of an element?

Atom, from the Greek atomos, 'uncuttable', a name coined long before anyone knew atoms could be split; an atom of gold keeps gold's chemistry, but its separated parts do not.

What is the name of the supercontinent that existed about 250 million years ago?

Pangaea was the supercontinent that contained all present-day continents. It began breaking apart about 200 million years ago due to plate tectonics, eventually forming the continents we know today.

What particle in an atom has a negative charge?

Electron, about 1,800 times lighter than a proton, and its charge, minus 1.6 × 10⁻¹⁹ coulombs, is the basic unit of electricity. Current in a wire is electrons shuffling along.

What is the normal resting heart rate for adults?

A normal adult resting heart rate is 60–100 bpm; elite endurance athletes can rest in the 40s because each beat pumps more blood.

What is Newton's First Law of Motion also known as?

The law of inertia: a body keeps its state of rest or uniform motion unless a force acts on it. Galileo had grasped the idea; Newton set it down as the first of his three laws in the 1687 Principia.

Which organ in the human body produces insulin?

The pancreas produces insulin in its beta cells within the islets of Langerhans. Insulin regulates blood sugar levels by allowing cells to absorb glucose from the bloodstream.

What is the theory that describes the origin of the universe?

The Big Bang Theory proposes that the universe began as an extremely hot, dense point approximately 13.8 billion years ago and has been expanding ever since. Evidence includes cosmic microwave background radiation.

What is the chemical symbol for iron?

Fe is from the Latin 'ferrum'; by mass, iron is the most common element on Earth because it makes up most of the core.

How long does it take for light from the Sun to reach Earth?

Light from the Sun takes approximately 8 minutes and 20 seconds to reach Earth, traveling about 150 million kilometers (93 million miles) at the speed of light.

What type of bond involves the sharing of electron pairs between atoms?

A covalent bond forms when two atoms share one or more pairs of electrons. This type of bonding is common in organic molecules and occurs between nonmetal atoms.

What is the largest planet in our solar system?

Jupiter, about 139,820 km across, more than eleven times Earth's diameter, and heavier than all the other planets combined. Its Great Red Spot is a storm bigger than Earth.

What is the double helix structure associated with?

DNA, and Watson and Crick's 1953 model relied on Rosalind Franklin's X-ray 'Photograph 51', which they saw without her knowledge. She died in 1958, four years before the Nobel Prize went to the men.

What is the Richter scale used to measure?

Earthquake strength, and each whole number is a tenfold jump in ground shaking, roughly 32 times the energy. Seismologists today mostly quote the moment magnitude scale instead, though the media still says 'Richter'.

Which scientist formulated the three laws of planetary motion?

Johannes Kepler published them between 1609 and 1619, working from Tycho Brahe's observations: orbits are ellipses, not circles, and planets speed up near the Sun.

What is absolute zero in Celsius?

Absolute zero is −273.15 °C, or 0 K, which equals −459.67 °F; labs have cooled atoms to within billionths of a degree of it but can never quite reach it.

What percentage of the human body is water?

The adult human body is approximately 60% water by mass. The brain and heart are about 73% water, while the lungs are about 83% water. Water is essential for virtually all bodily functions.

What did Marie Curie discover?

She discovered radium and polonium in 1898 with Pierre Curie, naming polonium after her native Poland; her 1903 Physics and 1911 Chemistry prizes made her the first person to win Nobels in two different sciences.

What is the Doppler effect?

It is why a siren drops in pitch as it passes, and why light from receding galaxies is shifted toward the red.

How many chromosomes do humans have?

Chimpanzees have 48; two ancestral ape chromosomes fused end to end to form human chromosome 2.

Which group contains the most reactive metals in the periodic table?

Alkali metals (Group 1) are the most reactive metals. They have one electron in their outer shell that they readily give up. Francium is theoretically the most reactive, but caesium is the most reactive that can be studied in quantity.

What layer of the Earth's atmosphere do we live in?

The troposphere: nearly all weather happens in it, and it is thinner at the poles (about 7 km) than at the equator (about 18 km).

Roughly how long is the half-life of carbon-14, the basis of radiocarbon dating?

After about ten half-lives too little remains to measure, so the method tops out at roughly 50,000 years.

Which scientist's law of universal gravitation is famously linked to a falling apple?

Isaac Newton, who also built the first practical reflecting telescope and spent more ink on alchemy and Bible prophecy than on physics. Einstein's relativity replaced his gravity only in 1915.

Which type of animal is classified in the order Chiroptera?

Chiroptera means 'hand-wing' in Greek; bats make up roughly a fifth of all mammal species.

Which of the four fundamental interactions holds atomic nuclei together?

The strong interaction, about 100 times stronger than electromagnetism at nuclear distances, is what overcomes the mutual repulsion of the protons and binds the nucleus together.

Which metal has the highest melting point of any pure metal?

Its symbol W comes from the German name Wolfram, and its 3,422 °C melting point is why it was used for light-bulb filaments.

Which planet spins with its axis tilted about 98 degrees, almost on its side?

Uranus rotates with its axis tilted about 98 degrees to its orbit, so each pole gets roughly 42 years of sunlight followed by 42 years of darkness; a giant impact is the leading explanation.

Which two substances are the main products of oxygenic photosynthesis?

Nearly all the oxygen in the air was released this way, and the process supplies most of the energy that complex life runs on.

What is the SI unit for electric current?

The SI unit of electric current is the Ampere (A), named after André-Marie Ampère. One ampere is equivalent to one coulomb of charge moving past a point per second.

Roughly how many elementary entities are in one mole of a substance?

One mole holds 6.022 × 10^23 entities, Avogadro's number; the 2019 redefinition of SI units fixed it exactly at 6.02214076 × 10^23, and the mole is the SI base unit for amount of substance.

Which element has the highest electronegativity on the Pauling scale?

Fluorine tops the Pauling scale at 3.98; it pulls electrons so strongly that it reacts with almost every other element, including noble gases such as xenon.

What was the profession of Alfred Wegener, who proposed continental drift in 1912?

Wegener was a meteorologist and polar researcher, not a geologist; partly because of that, and the lack of a physical mechanism, his idea was not widely accepted until plate tectonics emerged in the 1960s.

Physicists of which nationality discovered the ozone layer in 1913?

The French physicists Charles Fabry and Henri Buisson detected the ozone layer spectroscopically in 1913; the photochemical mechanism that creates it was worked out by the British physicist Sydney Chapman in 1930.

Who determined the molecular structure of hemoglobin in 1959?

Max Perutz solved hemoglobin's structure by X-ray crystallography in 1959 after more than twenty years' work, sharing the 1962 Nobel Prize in Chemistry with John Kendrew, who had solved the related protein myoglobin.

Which planet has the hottest surface in the solar system?

Venus's thick carbon-dioxide atmosphere traps heat, pushing surface temperatures to about 464 °C, hotter than Mercury despite being farther from the Sun.

Besides mercury, which element is a liquid at standard room conditions?

Bromine is a fuming reddish-brown liquid, discovered independently by Carl Jacob Löwig and Antoine Balard in the 1820s; gallium and caesium melt only above 28 °C, so they stay solid in a normal room.

Which mineral sits at 1, the softest point, on the Mohs hardness scale?

Friedrich Mohs introduced the scale in 1812; talc can be scratched with a fingernail.

Which is the largest moon in the solar system?

Ganymede is bigger than the planet Mercury and was first observed in 1610.

Which chemical element is named after a US state?

Californium was first made at Berkeley in 1950 and named for the state of California and its university; berkelium honours the city, americium the Americas, germanium Germany.

The chemical symbol Sb belongs to which element?

Antimony's symbol Sb comes from the Latin stibium, the name of its sulfide ore used as the eye cosmetic kohl in antiquity; the metalloid is alloyed with lead to harden bullets and type metal.

Which scientist coined the biological term 'cell' in the 1665 book Micrographia?

Robert Hooke, looking at cork under a microscope, thought the tiny compartments resembled honeycomb or monks' cells, and published the drawings in Micrographia in 1665.

In what year was Darwin's On the Origin of Species first published?

On the Origin of Species appeared on 24 November 1859; the first printing of 1,250 copies went on sale for fifteen shillings.

Edward Jenner's 1796 smallpox vaccine used material from which disease?

Jenner took cowpox pus from milkmaid Sarah Nelmes, who had caught it from a cow named Blossom, and inoculated eight-year-old James Phipps, who then resisted smallpox.

What is the smallest bone in the human body?

The stapes sits in the middle ear, about 3 mm long, and takes its name from the Latin for stirrup, which it resembles.

Who discovered the neutron in 1932?

James Chadwick announced it in a 1932 letter to Nature titled 'Possible Existence of a Neutron' and won the 1935 Nobel Prize in Physics for the discovery.

Which German scientist discovered X-rays in 1895?

Wilhelm Röntgen found the rays while experimenting with cathode-ray tubes in November 1895 and received the very first Nobel Prize in Physics, in 1901, for the discovery.

What is the SI unit of frequency?

It honours Heinrich Hertz, the first person to conclusively prove electromagnetic waves exist.

What is the SI unit of pressure?

It is named after Blaise Pascal, whose barometer experiments helped found hydrostatics.

Which SI unit of energy is named after an English physicist born in 1818?

James Prescott Joule, a brewer's son, showed that heat and mechanical work are interchangeable.

Who discovered Pluto in 1930?

Clyde Tombaugh, a 24-year-old assistant at Lowell Observatory, spotted Pluto on photographic plates in February 1930; the IAU reclassified it as a dwarf planet in 2006.

In which year is Halley's Comet next due to reach perihelion?

Halley's Comet last swung past the Sun in February 1986 and returns every 74–79 years; its following perihelion is predicted for July 2061.

Dry ice is the solid form of which gas?

Dry ice is frozen carbon dioxide; it skips the liquid phase entirely, subliming straight to gas at about −78.5 °C at normal pressure.

'Laughing gas' is the common name for which compound?

Nitrous oxide, N2O, was first made by Joseph Priestley in 1772, who called it 'dephlogisticated nitrous air'; Humphry Davy's 1799 self-experiments earned it the 'laughing gas' nickname.

Which element, number 43, was first identified by Perrier and Segrè in 1937?

Technetium takes its name from the Greek technetos, 'artificial', as the first element made rather than found; Carlo Perrier and Emilio Segrè identified it in Palermo in 1937 from a molybdenum plate irradiated in Berkeley's cyclotron.

The 1921 Nobel Prize in Physics was awarded for explaining which phenomenon?

Albert Einstein received it 'for his discovery of the law of the photoelectric effect'; the citation pointedly did not mention relativity, which the committee considered too contentious in 1922.

Rutherford's gold-foil experiments showed an atom's positive charge is concentrated where?

In a tiny nucleus: Hans Geiger and Ernest Marsden, working under Rutherford at Manchester from 1908 to 1913, fired alpha particles at gold foil, and the rare large deflections implied a dense, positively charged core.

The chemist who formulated the periodic law in 1869 was of what nationality?

He presented his table to the Russian Chemical Society in March 1869 and left gaps for elements not yet discovered.

Which element was discovered spectroscopically in 1868, 27 years before it was isolated on Earth?

Helium was named by Norman Lockyer after the Greek helios, the Sun, from a yellow line in the 1868 solar eclipse spectrum; William Ramsay isolated it on Earth in 1895, and it has the lowest boiling point of any element.

Roughly how fast does sound travel through air at 20 °C?

Sound moves at about 343 m/s in air at 20 °C, roughly a kilometre every three seconds, which is why you count seconds between lightning and thunder.

The kelvin temperature unit honours a physicist with what birth name?

William Thomson was ennobled as Baron Kelvin in 1892, taking the title from the River Kelvin that runs past the University of Glasgow, where he was professor for more than fifty years.

What was unusual about Anders Celsius's original 1742 temperature scale?

He set 0 as the boiling point of water and 100 as freezing; Carl Linnaeus reversed it in 1745, after Celsius had died.

Gregor Mendel worked out the laws of heredity using which plant?

His experiments ran from 1856 to 1863 in a monastery garden, and his work was largely ignored until 1900.

Jonas Salk developed one of the first successful vaccines against which disease?

Salk's polio vaccine, made from killed virus, was announced safe and effective on 12 April 1955, three years after the worst US epidemic year, 1952; Salk famously declined to patent it.

What is the hardest substance in the human body?

Tooth enamel is about 96% mineral, mostly hydroxyapatite, which is why it cannot regrow once worn away.

About how many bones does a typical adult human skeleton have?

A typical adult has 206 bones; newborns start with around 270, many of which fuse together during growth.

Which colour of visible light has the longest wavelength?

The human eye responds to wavelengths from about 380 to 750 nanometres, with red at the long end and violet at the short end.

Which pigment gives most plants their green colour?

Chlorophyll absorbs mostly blue and red light, so the green in between is reflected back to our eyes; carotenes and xanthophylls show through when it breaks down in autumn.

What is the largest animal known to have ever existed?

Blue whales reach about 30 metres and up to 200 tonnes, heavier than any known dinosaur; Argentinosaurus is estimated at well under 100 tonnes.

Which Swedish scientist formalised the two-part Latin naming system for species?

Carl Linnaeus set out binomial names in Systema Naturae, whose 1758 tenth edition is the starting point of zoological nomenclature; he is the reason humans are Homo sapiens.

Who coined the word 'plasma' for ionised gas in 1928?

Irving Langmuir, working at General Electric, borrowed the term from blood plasma in 1928; an estimated 99% of ordinary matter in the universe is in this state.

What is the estimated age of the Earth?

Earth is about 4.54 billion years old, a figure from radiometric dating of meteorites by Clair Patterson in 1956; 13.8 billion is the age of the universe.

The Challenger Deep, the ocean's deepest point, lies in a trench named for which islands?

The Mariana Trench's Challenger Deep was measured at about 10,935 metres in a 2021 survey, deep enough to swallow Mount Everest with more than two kilometres to spare.

Tardigrades are better known by which nickname?

Water bears, eight-legged micro-animals under a millimetre long, survived direct exposure to the vacuum of space on the 2007 FOTON-M3 orbital mission.

A light-year is a unit of what?

A light-year is a distance: the length light travels in a vacuum in one Julian year, about 9.46 trillion kilometres.