Science

Traffic lights, traffic signals, or stoplights – also known as robots in South Africa, Zambia, and Namibia – are signalling devices positioned at road intersections, pedestrian crossings, and other locations to control the flow of traffic.

The Sun is the star located at the centre of the Solar System. It is a massive sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light and infrared radiation with 10% at ultraviolet energies. It is the main source of energy for life on Earth. The…

The Moon is the only natural satellite of Earth. It orbits around Earth at an average distance of 384,399 kilometers (238,854 mi), a distance roughly 30 times the width of Earth. It completes an orbit in relation to Earth and the Sun (synodically) every 29.5 days. The Moon and Earth are bound by gravitational attraction, which is…

Earth is the third planet from the Sun and the only astronomical object known to harbor life. This is made possible by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all of Earth's water is contained in its ocean, which covers 70.8% of Earth's crust. The remaining 29.2% of Earth's…

The Moon is the only natural satellite of Earth. It orbits around Earth at an average distance of 384,399 kilometers (238,854 mi), a distance roughly 30 times the width of Earth. It completes an orbit in relation to Earth and the Sun (synodically) every 29.5 days. The Moon and Earth are bound by gravitational attraction, which is…

Mars is the fourth planet from the Sun. It is also known as the "Red Planet", for its orange-red appearance. Mars is a desert-like rocky planet with a tenuous atmosphere that is primarily carbon dioxide. At the average surface level the atmospheric pressure is a few thousandths of Earth's, atmospheric temperature ranges from −153 to 20…

Lava is magma that has been expelled from the interior of a terrestrial planet or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or underwater, usually at temperatures from 800 to 1,200 °C. Lava may be erupted directly onto the land surface or onto the sea floor or it may be ejected…

Jupiter is the fifth planet from the Sun, and the largest in the Solar System. This is a gas giant with a mass nearly 2.5 times that of all the other planets in the Solar System combined and slightly less than one-thousandth the mass of the Sun. Its diameter is 11 times that of Earth and a tenth that of the Sun. Jupiter orbits the Sun at…

Amber is fossilized tree resin. It has been appreciated for its color and natural beauty since the Neolithic times, and worked as a gemstone since classical antiquity. Amber is used in jewelry and as a healing agent in folk medicine.

Water is an inorganic compound with the chemical formula H2O. It is a transparent, tasteless, odorless, and nearly colorless chemical substance. It is the main constituent of Earth's streams, lakes, and oceans. Water is also the fluid of all known living organisms, in which it acts as a solvent. Water, being a polar molecule, undergoes…

The Lampyridae are a family of elateroid beetles with more than 2,400 described species, many of which are light-emitting. They are soft-bodied beetles commonly called fireflies, lightning bugs, or glowworms for their conspicuous production of light, mainly during twilight, to attract mates. The type species is Lampyris noctiluca, the…

Paleontology or palaeontology is the scientific study of the life of the past, mainly but not exclusively through the study of fossils. Paleontologists use fossils as a means to classify organisms, measure geologic time, and assess the interactions between prehistoric organisms and their natural environment. While paleontological…

Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth of the average density of Earth, but is over 95 times more massive. Even though Saturn is almost as big as Jupiter, Saturn has less than a third of…

Columbidae is a bird family consisting of doves and pigeons. It is the only family in the order Columbiformes. These are stout-bodied birds with small heads, relatively short necks and slender bills that in some species feature fleshy ceres. They feed largely on plant matter, feeding on seeds (granivory), fruit (frugivory), and foliage (folivory).

Mercury is the first planet from the Sun and the smallest in the Solar System. It is a rocky planet with a trace atmosphere and a surface gravity slightly higher than that of Mars. The surface of Mercury is similar to Earth's Moon, being cratered, with an expansive rupes system generated from thrust faults, and bright ray systems, formed…

The giant panda, also known as the panda bear or simply panda, is a bear species endemic to China. It is characterised by its white coat with black patches around the eyes, ears, legs and shoulders. Its body is rotund; adult individuals weigh 100 to 115 kg and are typically 1.2 to 1.9 m long. It is sexually dimorphic, with males being…

In geometry, a hexagon is a six-sided polygon. The total of the internal angles of any simple (non-self-intersecting) hexagon is 720°.

Oxygen is a chemical element; it has the symbol O and its atomic number is 8. It is a member of the chalcogen group in the periodic table. It is highly reactive, a nonmetal, and a potent oxidizing agent that readily forms oxides with most elements as well as with other compounds. Oxygen is the most abundant element in Earth's crust,…

Jupiter is the fifth planet from the Sun, and the largest in the Solar System. This is a gas giant with a mass nearly 2.5 times that of all the other planets in the Solar System combined and slightly less than one-thousandth the mass of the Sun. Its diameter is 11 times that of Earth and a tenth that of the Sun. Jupiter orbits the Sun at…

A planet is a large, rounded astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. The Solar System has eight planets by the most restrictive definition of the term: the terrestrial planets Mercury, Venus, Earth, and Mars, and the giant planets Jupiter, Saturn,…

Sir Isaac Newton was an English polymath active as an mathematician, physicist, astronomer, alchemist, theologian, author and inventor. He was a key figure in the Scientific Revolution and the Enlightenment that followed. His book Philosophiæ Naturalis Principia Mathematica, first published in 1687, achieved the first great unification…

The heart is a muscular organ found in humans and other animals. This organ pumps blood through the blood vessels. The heart and blood vessels together make up the circulatory system. The pumped blood carries oxygen and nutrients to the tissue, while carrying metabolic waste such as carbon dioxide to the lungs. In humans, the heart is…

In physics, gravity, also known as gravitation or a gravitational interaction, is a fundamental interaction, which may be described as the force that draws material objects towards each other.

Uranus is the seventh planet from the Sun. It is a gaseous cyan-coloured ice giant. Most of the planet is made of water, ammonia, and methane in a supercritical phase of matter, which astronomy calls "ice" or volatiles. The planet's atmosphere has a complex layered cloud structure and has the lowest minimum temperature of all the Solar…

Gold is a chemical element; its chemical symbol is Au and atomic number 79. In its pure form, it is a bright-metallic-yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal, a group 11 element, and one of the noble metals. It is one of the least reactive chemical elements, being the second lowest in the…

Earth orbits the Sun at an average distance of 149.60 million km (92.96 million mi), or 8.317 light-minutes, in a counterclockwise direction as viewed from above the Northern Hemisphere. One complete orbit takes 365.256 days, during which time Earth has traveled 940 million km (584 million mi). Ignoring the influence of other Solar…

Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation.

A thermometer is a device that measures temperature or temperature gradient. A thermometer has two important elements: (1) a temperature sensor in which some change occurs with a change in temperature; and (2) some means of converting this change into a numerical value. Thermometers are widely used in technology and industry to monitor…

Venus is the second planet from the Sun. Similar in size and mass to Earth, Venus has no liquid water, and its atmosphere is far thicker and denser than that of any other rocky body in the Solar System. The atmosphere is composed mostly of carbon dioxide and has a thick cloud layer of sulfuric acid that spans the whole planet. At the…

A liquid metal is a metal or a metal alloy which is liquid at or near room temperature.

An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers study astronomical objects, such as stars, planets, moons, comets and galaxies, by some combination of observation and the application of astrophysical models. Examples of topics or fields astronomers…

Diamond is a mineral form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Diamond is a tasteless, odorless, strong, brittle solid, a poor conductor of electricity, colorless in pure form, and insoluble in water. Another solid form of carbon known as graphite is the chemically stable form of…

Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth of the average density of Earth, but is over 95 times more massive. Even though Saturn is almost as big as Jupiter, Saturn has less than a third of…

Nitrogen is a chemical element; it has symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seventh in total abundance in the Milky Way and the Solar System. At standard temperature and pressure,…

A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby obscuring the view of the Sun from a small part of Earth, totally or partially. Such an alignment occurs approximately every six months, during the eclipse season in its new moon phase, when the Moon's orbital plane is closest to the plane of Earth's orbit. In…

Mercury is the first planet from the Sun and the smallest in the Solar System. It is a rocky planet with a trace atmosphere and a surface gravity slightly higher than that of Mars. The surface of Mercury is similar to Earth's Moon, being cratered, with an expansive rupes system generated from thrust faults, and bright ray systems, formed…

Earth is the third planet from the Sun and the only astronomical object known to harbor life. This is made possible by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all of Earth's water is contained in its ocean, which covers 70.8% of Earth's crust. The remaining 29.2% of Earth's…

Blinking is a bodily function; it is a semi-autonomic rapid closing of the eyelid. A single blink consists of the closing of the eyelid or inactivation of the levator palpebrae superioris and the activation of the palpebral portion of the orbicularis oculi. It is an essential function of the eye that helps spread tears across and remove…

The Milky Way or Milky Way Galaxy, or simply the Galaxy, is the galaxy that includes the Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galaxy, which are so far away that they cannot be individually distinguished by the naked eye.

Venus is the second planet from the Sun. Similar in size and mass to Earth, Venus has no liquid water, and its atmosphere is far thicker and denser than that of any other rocky body in the Solar System. The atmosphere is composed mostly of carbon dioxide and has a thick cloud layer of sulfuric acid that spans the whole planet. At the…

Carbon dioxide is a chemical compound with the chemical formula CO2. It is made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at normally-encountered concentrations it is odorless. As the source of carbon in the carbon cycle, atmospheric CO2…

The femur, or thigh bone is the only bone in the thigh — the region of the lower limb between the hip and the knee. In many four-legged animals, the femur is the upper bone of the hindleg.

Neptune is the eighth and farthest known planet orbiting the Sun. It is the fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times the mass of Earth. Compared to Uranus, its neighbouring ice giant, Neptune is slightly smaller, but more massive and dense. Being…

Deoxyribonucleic acid is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses. DNA and ribonucleic acid (RNA) are nucleic acids. Alongside proteins,…

The liver is a major metabolic organ exclusively found in vertebrates, which performs many essential biological functions such as detoxification of the organism, and the synthesis of various proteins and various other biochemicals necessary for digestion and growth. In humans, it is located in the right upper quadrant of the abdomen,…

Chemical symbols are the abbreviations used in chemistry, mainly for chemical elements, but also for functional groups, chemical compounds, and other entities. Element symbols for chemical elements, also known as atomic symbols, normally consist of one or two letters from the Latin alphabet and are written with the first letter capitalised.

Venus is the second planet from the Sun. Similar in size and mass to Earth, Venus has no liquid water, and its atmosphere is far thicker and denser than that of any other rocky body in the Solar System. The atmosphere is composed mostly of carbon dioxide and has a thick cloud layer of sulfuric acid that spans the whole planet. At the…

Titan is the largest moon of Saturn and the second largest in the Solar System. It is the only moon known to have a dense atmosphere—denser than Earth's—and is the only known object in the Solar System besides Earth with clear evidence of stable bodies of surface liquid. Titan is one of seven gravitationally rounded moons of Saturn and…

Mars is the fourth planet from the Sun. It is also known as the "Red Planet", for its orange-red appearance. Mars is a desert-like rocky planet with a tenuous atmosphere that is primarily carbon dioxide. At the average surface level the atmospheric pressure is a few thousandths of Earth's, atmospheric temperature ranges from −153 to 20…

Helium is a chemical element; it has symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. Its boiling point is the lowest among all the elements, and it does not have a melting point at standard pressures. It is the second-lightest and…

The Great Red Spot is a persistent, high-pressure region in the atmosphere of the planet Jupiter, producing the largest anticyclonic storm in the Solar System. It is the most recognizable feature on Jupiter, owing to its red-orange color whose origin is still unknown. Located 22 degrees south of Jupiter's equator, it produces wind-speeds…

Pluto is a dwarf planet in the Kuiper belt, a ring of bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Sun. It is the largest known trans-Neptunian object by volume by a small margin, but is less massive than Eris. Like other Kuiper belt objects, Pluto is made primarily…

A blood type is a classification of blood based on the presence and absence of antibodies and inherited antigenic substances on the surface of red blood cells (RBCs). These antigens may be proteins, carbohydrates, glycoproteins, or glycolipids, depending on the blood group system. Some of these antigens are also present on the surface of…

Sodium chloride, is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. It is transparent or translucent, brittle, hygroscopic, and occurs as the mineral halite. In its edible form, common table salt, it is commonly used as a condiment and food preservative. Large quantities of sodium…

Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth of the average density of Earth, but is over 95 times more massive. Even though Saturn is almost as big as Jupiter, Saturn has less than a third of…

Sir Isaac Newton was an English polymath active as an mathematician, physicist, astronomer, alchemist, theologian, author and inventor. He was a key figure in the Scientific Revolution and the Enlightenment that followed. His book Philosophiæ Naturalis Principia Mathematica, first published in 1687, achieved the first great unification…

Potassium is a chemical element; it has symbol K and atomic number 19. It is a silvery white metal that is soft enough to easily cut with a knife. Potassium metal reacts rapidly with atmospheric oxygen to form flaky white potassium peroxide in only seconds of exposure. It was first isolated from potash, the ashes of plants, from which…

Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth of the average density of Earth, but is over 95 times more massive. Even though Saturn is almost as big as Jupiter, Saturn has less than a third of…

The International System of Units, internationally known by the abbreviation SI, is the modern form of the metric system and the world's most widely used system of measurement. It is the only system of measurement with official status in nearly every country in the world, employed in science, technology, industry, and everyday…

Iron is a chemical element; it has symbol Fe and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's outer and inner core. It is the fourth most abundant element in the Earth's crust. In its metallic state…

Uranus is the seventh planet from the Sun. It is a gaseous cyan-coloured ice giant. Most of the planet is made of water, ammonia, and methane in a supercritical phase of matter, which astronomy calls "ice" or volatiles. The planet's atmosphere has a complex layered cloud structure and has the lowest minimum temperature of all the Solar…

The Rh blood group system is a human blood group system. It contains proteins on the surface of red blood cells. After the ABO blood group system, it is most likely to be involved in transfusion reactions. The Rh blood group system consists of over 50 defined blood group antigens, of which the five antigens D, C, c, E, and e are among…

Distance is a numerical or occasionally qualitative measurement of how far apart objects, points, people, or ideas are. In physics or everyday usage, distance may refer to a physical length or an estimation based on other criteria. The term is also frequently used metaphorically to mean a measurement of the amount of difference between…

Hydrogen is a chemical element; it has the symbol H and atomic number 1. It is the lightest and most abundant chemical element in the universe, constituting about 75% of all normal matter. Under standard conditions, hydrogen is a gas of diatomic molecules with the formula H2, called dihydrogen, or sometimes hydrogen gas, molecular…

The pancreas is an organ of the digestive system and endocrine system of vertebrates. In humans, it is located in the abdomen behind the stomach and functions as a gland. The pancreas is a mixed or heterocrine gland, i.e., it has both an endocrine and a digestive exocrine function. Ninety-nine percent of the pancreas is exocrine and 1%…

Mars is the fourth planet from the Sun. It is also known as the "Red Planet", for its orange-red appearance. Mars is a desert-like rocky planet with a tenuous atmosphere that is primarily carbon dioxide. At the average surface level the atmospheric pressure is a few thousandths of Earth's, atmospheric temperature ranges from −153 to 20…

The heart is a muscular organ found in humans and other animals. This organ pumps blood through the blood vessels. The heart and blood vessels together make up the circulatory system. The pumped blood carries oxygen and nutrients to the tissue, while carrying metabolic waste such as carbon dioxide to the lungs. In humans, the heart is…

The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate.

Silver is a chemical element; it has symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity and reflectivity of any metal. Silver is found in the Earth's crust in the pure, free elemental form, as an alloy with gold and other metals, and in minerals…

Sir Isaac Newton was an English polymath active as an mathematician, physicist, astronomer, alchemist, theologian, author and inventor. He was a key figure in the Scientific Revolution and the Enlightenment that followed. His book Philosophiæ Naturalis Principia Mathematica, first published in 1687, achieved the first great unification…

Neptune is the eighth and farthest known planet orbiting the Sun. It is the fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times the mass of Earth. Compared to Uranus, its neighbouring ice giant, Neptune is slightly smaller, but more massive and dense. Being…

A capillary is a small blood vessel, from 5 to 10 micrometres in diameter, and is part of the microcirculation system. Capillaries are microvessels and the smallest blood vessels in the body. They are composed of only the tunica intima, consisting of a thin wall of simple squamous endothelial cells. They are the site of the exchange of…

Carbon dioxide is a chemical compound with the chemical formula CO2. It is made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at normally-encountered concentrations it is odorless. As the source of carbon in the carbon cycle, atmospheric CO2…

Saturn is the sixth planet from the Sun and the second largest in the Solar System, after Jupiter. It is a gas giant, with an average radius of about 9 times that of Earth. It has an eighth of the average density of Earth, but is over 95 times more massive. Even though Saturn is almost as big as Jupiter, Saturn has less than a third of…

Tungsten is a chemical element; it has symbol W and atomic number 74. It is a metal found naturally on Earth almost exclusively in compounds with other elements. It was identified as a distinct element in 1781 and first isolated as a metal in 1783. Its important ores include scheelite and wolframite, the latter lending the element its alternative name.

Alfred Russel Wallace was an English naturalist, explorer, geographer, anthropologist, biologist and illustrator. He independently conceived the theory of evolution through natural selection; his 1858 paper on the subject was published that year alongside extracts from Charles Darwin's writings on the topic. It spurred Darwin to set…

Hemoglobin is a protein containing iron that facilitates the transportation of oxygen in red blood cells. Almost all vertebrates contain hemoglobin, with the sole exception of the fish family Channichthyidae. Hemoglobin in the blood carries oxygen from the respiratory organs to the other tissues of the body, where it releases the oxygen…

Hydrogen is a chemical element; it has the symbol H and atomic number 1. It is the lightest and most abundant chemical element in the universe, constituting about 75% of all normal matter. Under standard conditions, hydrogen is a gas of diatomic molecules with the formula H2, called dihydrogen, or sometimes hydrogen gas, molecular…

Jupiter is the fifth planet from the Sun, and the largest in the Solar System. This is a gas giant with a mass nearly 2.5 times that of all the other planets in the Solar System combined and slightly less than one-thousandth the mass of the Sun. Its diameter is 11 times that of Earth and a tenth that of the Sun. Jupiter orbits the Sun at…

Tungsten is a chemical element; it has symbol W and atomic number 74. It is a metal found naturally on Earth almost exclusively in compounds with other elements. It was identified as a distinct element in 1781 and first isolated as a metal in 1783. Its important ores include scheelite and wolframite, the latter lending the element its alternative name.

Jupiter is the fifth planet from the Sun, and the largest in the Solar System. This is a gas giant with a mass nearly 2.5 times that of all the other planets in the Solar System combined and slightly less than one-thousandth the mass of the Sun. Its diameter is 11 times that of Earth and a tenth that of the Sun. Jupiter orbits the Sun at…

Antoine Henri Becquerel was a French experimental physicist who shared the 1903 Nobel Prize in Physics with Marie and Pierre Curie for his discovery of radioactivity.

Silicon is a chemical element; it has symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a tetravalent non-metal and semiconductor. It is a member of group 14 in the periodic table: carbon is above it; and germanium, tin, lead, and flerovium are below it. It is relatively…

Neptune is the eighth and farthest known planet orbiting the Sun. It is the fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times the mass of Earth. Compared to Uranus, its neighbouring ice giant, Neptune is slightly smaller, but more massive and dense. Being…

Insulin is a peptide hormone produced by beta cells of the pancreatic islets encoded in humans by the insulin (INS) gene. It is the main anabolic hormone of the body. It regulates the metabolism of carbohydrates, fats, and protein by promoting the absorption of glucose from the blood into cells of the liver, fat, and skeletal muscles. In…

The stapes or stirrup is a bone in the middle ear of humans and other tetrapods which is involved in the conduction of sound vibrations to the inner ear. This bone is connected to the oval window by its annular ligament, which allows the footplate to transmit sound energy through the oval window into the inner ear. The stapes is the…

Lead is a chemical element with the symbol Pb and atomic number 82. It is a heavy metal, denser than most common materials. Lead is soft, malleable, and has a relatively low melting point. When freshly cut or melted, it appears shiny silvery with a bluish tint, but tarnishes to dull gray on exposure to air. Lead has the highest atomic…

Venus is the second planet from the Sun. Similar in size and mass to Earth, Venus has no liquid water, and its atmosphere is far thicker and denser than that of any other rocky body in the Solar System. The atmosphere is composed mostly of carbon dioxide and has a thick cloud layer of sulfuric acid that spans the whole planet. At the…

A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word laser originated as an acronym for light amplification by stimulated emission of radiation. The first laser was built in 1960 by Theodore Maiman at Hughes Research Laboratories, based on…

The list of human cell types provides an enumeration and description of the various specialized cells found within the human body, highlighting their distinct functions, characteristics, and contributions to overall physiological processes. Cells may be classified by their physiological function, histology, lineage, or gene expression.

Hypertension, also known as high blood pressure, is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms itself. It is, however, a major risk factor for stroke, coronary artery disease, heart failure, atrial fibrillation, peripheral…

Sirius is the brightest star in the night sky, located in the southern constellation of Canis Major. Its name is derived from the Greek word Σείριος. The star is designated α Canis Majoris, Latinized to Alpha Canis Majoris, and abbreviated α CMa or Alpha CMa. With a visual apparent magnitude of −1.46, Sirius is almost twice as bright as…

Nitrous oxide, commonly known as laughing gas or nitrous, among others, is a chemical compound, an oxide of nitrogen with the formula N2O. At room temperature, it is a colourless non-flammable gas, and has a slightly sweet scent and taste. At elevated temperatures, nitrous oxide is a powerful oxidiser similar to molecular oxygen.

The electron is a subatomic particle whose electric charge is negative one elementary charge. It is an elementary particle that comprises the ordinary matter that makes up the universe.

Robert Hooke was an English polymath who was active as a physicist, astronomer, geologist, meteorologist, and architect. He is credited as one of the first scientists to investigate living things at microscopic scale in 1665, using a compound microscope that he designed. Hooke was an impoverished scientific inquirer in young adulthood…

The gluteus maximus is the main extensor muscle of the hip in humans. It is the largest and outermost of the three gluteal muscles and makes up a large part of the shape and appearance of each side of the hips. It is the single largest muscle in the human body. Its thick fleshy mass, in a quadrilateral shape, forms the prominence of the…

Jupiter is the fifth planet from the Sun, and the largest in the Solar System. This is a gas giant with a mass nearly 2.5 times that of all the other planets in the Solar System combined and slightly less than one-thousandth the mass of the Sun. Its diameter is 11 times that of Earth and a tenth that of the Sun. Jupiter orbits the Sun at…

Helium is a chemical element; it has symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. Its boiling point is the lowest among all the elements, and it does not have a melting point at standard pressures. It is the second-lightest and…

Horseshoe crabs are arthropods of the family Limulidae and the only surviving xiphosurans. Despite their name, they are not crabs or even crustaceans; they are chelicerates, more closely related to arachnids like spiders, ticks, and scorpions. The body of a horseshoe crab is divided into three main parts: the cephalothorax, abdomen, and…

Neon is a chemical element; it has the symbol Ne and the atomic number 10. It is the second noble gas in the periodic table. Neon is a colorless, odorless, inert monatomic gas under standard conditions, with approximately two-thirds the density of air.

The liver is a major metabolic organ exclusively found in vertebrates, which performs many essential biological functions such as detoxification of the organism, and the synthesis of various proteins and various other biochemicals necessary for digestion and growth. In humans, it is located in the right upper quadrant of the abdomen,…

Silver is a chemical element; it has symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity and reflectivity of any metal. Silver is found in the Earth's crust in the pure, free elemental form, as an alloy with gold and other metals, and in minerals…

Chemical symbols are the abbreviations used in chemistry, mainly for chemical elements, but also for functional groups, chemical compounds, and other entities. Element symbols for chemical elements, also known as atomic symbols, normally consist of one or two letters from the Latin alphabet and are written with the first letter capitalised.

Bromine is a chemical element; it has symbol Br and atomic number 35. It is a volatile red-brown liquid at room temperature that evaporates readily to form a similarly coloured vapour. Its properties are intermediate between those of chlorine and iodine. Isolated independently by two chemists, Carl Jacob Löwig and Antoine Jérôme Balard,…

Io is the innermost and second smallest of the four Galilean moons of Jupiter. Slightly larger than Earth's Moon, Io is the fourth-largest natural satellite in the Solar System, has the highest density and strongest surface gravity of any natural satellite, and the lowest amount of water by atomic ratio of any known astronomical object in the Solar System.

Astatine is a chemical element; it has symbol At and atomic number 85. It is the rarest naturally occurring element in the Earth's crust, occurring only as the decay product of various heavier elements. All of astatine's isotopes are short-lived; the most stable is astatine-210, with a half-life of 8.1 hours. Consequently, a solid sample…

Alfred Lothar Wegener was a German climatologist, geologist, geophysicist, meteorologist, and polar researcher.

Neptune is the eighth and farthest known planet orbiting the Sun. It is the fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times the mass of Earth. Compared to Uranus, its neighbouring ice giant, Neptune is slightly smaller, but more massive and dense. Being…

Mauna Loa is one of five volcanoes that form the Island of Hawaii in the U.S. state of Hawaii in the Pacific Ocean. Mauna Loa is Earth's largest active volcano by both mass and volume. It was historically considered to be the largest volcano on Earth until the submarine mountain Tamu Massif was discovered to be larger. Mauna Loa is a…

Chemical symbols are the abbreviations used in chemistry, mainly for chemical elements, but also for functional groups, chemical compounds, and other entities. Element symbols for chemical elements, also known as atomic symbols, normally consist of one or two letters from the Latin alphabet and are written with the first letter capitalised.

Robert Hooke was an English polymath who was active as a physicist, astronomer, geologist, meteorologist, and architect. He is credited as one of the first scientists to investigate living things at microscopic scale in 1665, using a compound microscope that he designed. Hooke was an impoverished scientific inquirer in young adulthood…

Sir Joseph John Thomson was a British physicist. He received the 1906 Nobel Prize in Physics "in recognition of the great merits of his theoretical and experimental investigations on the conduction of electricity by gases." In 1897, he showed that cathode rays were composed of previously unknown negatively charged particles, which he…

The liver is a major metabolic organ exclusively found in vertebrates, which performs many essential biological functions such as detoxification of the organism, and the synthesis of various proteins and various other biochemicals necessary for digestion and growth. In humans, it is located in the right upper quadrant of the abdomen,…

White blood cells, also called immune cells or immunocytes, are cells of the immune system that are involved in protecting the body against both infectious disease and foreign entities. White blood cells are generally larger than red blood cells. They include three main subtypes: granulocytes, lymphocytes and monocytes.

Mercury is a chemical element; it has symbol Hg and atomic number 80. It is commonly known as quicksilver. A heavy, silvery d-block element, mercury is the only metallic element that is known to be liquid at standard temperature and pressure. As well as having the lowest freezing point, mercury has the lowest boiling point and…

The Royal Air Force (RAF) is the air and space force of the United Kingdom, British Overseas Territories and Crown Dependencies. It was formed towards the end of the First World War on 1 April 1918 through the merger of the Royal Flying Corps (RFC) and the Royal Naval Air Service (RNAS). Following the Allied victory over the Central…

Johannes Kepler was a German polymath who was an astronomer, mathematician, astrologer, natural philosopher and music theorist. He is a key figure in the 17th-century Scientific Revolution, best known for his laws of planetary motion, and his books Astronomia nova, Harmonice Mundi, and Epitome Astronomiae Copernicanae. The variety and…

Methane is a chemical compound that has the chemical formula CH4. It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The abundance of methane on Earth makes it an economically attractive fuel, although capturing and storing it is difficult because it is a gas at standard temperature and pressure. In…

The hertz is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event per second. The hertz is an SI derived unit whose formal expression in terms of SI base units is 1/s or s−1, meaning that one hertz is one per second or the reciprocal of one second. It is used only in the case…

Sodium is a chemical element; it has symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable isotope is 23Na. The free metal does not occur in nature and must be prepared from compounds. Sodium is the sixth–most abundant element…

Rhenium is a chemical element; it has symbol Re and atomic number 75. It is a silvery-gray, heavy, third-row transition metal in group 7 of the periodic table. With an estimated average concentration of 1 part per billion (ppb), rhenium is one of the rarest elements in the Earth's crust. It has one of the highest melting and boiling…

Edwin Powell Hubble was an American astronomer. He played a crucial role in establishing the fields of extragalactic astronomy and observational cosmology. Hubble proved that many objects previously thought to be clouds of dust and gas and classified as "nebulae" were actually galaxies beyond the Milky Way. He used the strong direct…

Adenosine triphosphate (ATP) is a nucleoside triphosphate that provides free energy of approximately 58 kJ/mol to drive and support many processes in living cells, such as muscle contraction, nerve impulse propagation, and chemical synthesis. Found in all known forms of life, it is often referred to as the "molecular unit of currency"…

Uranium is a chemical element; it has symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium radioactively decays, usually by emitting an alpha particle. The half-life of this decay varies between…

Ganymede is a natural satellite of Jupiter and is the largest and most massive moon in the Solar System. Like Saturn's largest moon, Titan, it is larger than the planet Mercury, but has somewhat less surface gravity than Mercury, Io, or Earth's Moon due to its lower density compared to the three. Ganymede orbits Jupiter in roughly seven…

A gravitational lens is matter, such as a cluster of galaxies or a point particle, that bends light from a distant source as it travels toward an observer. The amount of gravitational lensing is described by Albert Einstein's general theory of relativity. If light is treated as corpuscles travelling at the speed of light, Newtonian…

Apparent magnitude is a measure of the brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction of the object's light caused by interstellar dust or atmosphere along the line of sight to the observer.

Formic acid, systematically named methanoic acid, is the simplest carboxylic acid. It has the chemical formula HCOOH and structure H−C(=O)−O−H. This acid is an important intermediate in chemical synthesis and occurs naturally, most notably in some ants. Esters, salts, and the anion derived from formic acid are called formates.…

An apsis is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides is the line connecting the two extreme values.

Salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as rock salt or halite. Salt is essential for life in general, and saltiness is one of the basic human tastes. Salt is…

The Drake equation is a probabilistic argument used to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way Galaxy.

The positron or antielectron is the particle with an electric charge of +1e, a spin of 1/2 ħ, and the same mass as an electron. It is the antiparticle of the electron. When a positron collides with an electron, annihilation occurs. If this collision occurs at low energies, it results in the production of two or more photons.

The hadal zone, also known as the hadopelagic zone, is the deepest region of the ocean, lying within oceanic trenches. The hadal zone ranges from around 6 to 11 km below sea level, and exists in long, narrow, topographic V-shaped depressions.

James Clerk Maxwell was a Scottish physicist and mathematician who was responsible for the classical theory of electromagnetic radiation, which was the first theory to describe electricity, magnetism and light as different manifestations of the same phenomenon. Maxwell's equations for electromagnetism achieved the second great…

An endotherm is an organism that maintains its body at a metabolically favorable temperature, largely by the use of heat released by its internal bodily functions instead of relying almost purely on ambient heat. Such internally generated heat is mainly an incidental product of the animal's routine metabolism, but under conditions of…

Ernest Rutherford, 1st Baron Rutherford of Nelson, was a New Zealand physicist and chemist who was a pioneering researcher in both atomic and nuclear physics. He has been described as "the father of nuclear physics" and "the greatest experimentalist since Michael Faraday." In 1908, he was awarded the Nobel Prize in Chemistry "for his…

Vega is the brightest star in the northern constellation of Lyra. It has the Bayer designation α Lyrae, which is Latinised to Alpha Lyrae and abbreviated Alpha Lyr or α Lyr. This star is relatively close to the Solar System, at only 25 light-years from the Sun, and one of the most luminous stars in the Sun's neighborhood, being…

Copper is a chemical element; it has symbol Cu and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orange color. Copper is used as a conductor of heat and electricity, as a building material, and as a constituent of…

Maria Salomea Skłodowska Curie, better known as Marie Curie was a Polish and naturalised-French physicist and chemist. She shared the 1903 Nobel Prize in Physics with her husband, Pierre Curie, "for their joint researches on the radioactivity phenomena discovered by Professor Henri Becquerel". She won the 1911 Nobel Prize in Chemistry…

Antonie Philips van Leeuwenhoek was a Dutch microbiologist and microscopist in the Golden Age of Dutch art, science and technology. A largely self-taught man in science, he is commonly known as "the Father of Microbiology", and one of the first microscopists and microbiologists. Van Leeuwenhoek is best known for his pioneering work in…

Helium is a chemical element; it has symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. Its boiling point is the lowest among all the elements, and it does not have a melting point at standard pressures. It is the second-lightest and…

Hydrogen is a chemical element; it has the symbol H and atomic number 1. It is the lightest and most abundant chemical element in the universe, constituting about 75% of all normal matter. Under standard conditions, hydrogen is a gas of diatomic molecules with the formula H2, called dihydrogen, or sometimes hydrogen gas, molecular…

My Golden Blood is a 2025 Thai fantasy television series based on the novel of the same name. It was broadcast every Sunday from 20:50 to 21:45 (ICT) on MCOT HD, while the uncut version was shown on Line TV at midnight of the same day. The series consisted of a total of 12 episodes and premiered on 15 May 2025 until 31 July 2025. It…

Osmium is a chemical element; it has symbol Os and atomic number 76. It is a hard, brittle, bluish-white transition metal in the platinum group. Osmium has the highest density of any stable element and one of the lowest abundances in the Earth's crust. Manufacturers use alloys of osmium with platinum, iridium, and other platinum-group…

The spermaceti organ is an organ present in the heads of toothed whales of the superfamily Physeteroidea, in particular the sperm whale. The organ contains a waxy liquid called spermaceti and is thought to be involved in the generation of sound.

In astrophysics, the carbon–nitrogen–oxygen cycle, sometimes called Bethe–Weizsäcker cycle after Hans Albrecht Bethe and Carl Friedrich von Weizsäcker, is one of the two known sets of fusion reactions by which stars convert hydrogen to helium, the other being the proton–proton chain reaction, which is more efficient at the Sun's core…

Helicases are a class of enzymes that are vital to all organisms. Their main function is to unpack an organism's genetic material. Helicases are motor proteins that move directionally along a nucleic double helix, separating the two hybridized nucleic acid strands, via the energy gained from ATP hydrolysis. There are many helicases,…

A neutron star is the gravitationally collapsed core of a massive supergiant star. It results from the supernova explosion of a massive star—combined with gravitational collapse—that compresses the core past white dwarf star density to that of atomic nuclei. Surpassed only by black holes, neutron stars are the second-smallest and…

Aluminium or aluminum is a chemical element; it has symbol Al and atomic number 13. It has a density lower than other common metals, about one-third that of steel. Aluminium has a great affinity toward oxygen, forming a protective layer of oxide on the surface when exposed to air. It visually resembles silver, both in its color and in…

Rigel is a blue supergiant star in the equatorial constellation of Orion. It has the Bayer designation β Orionis, which is Latinized to Beta Orionis and abbreviated Beta Ori or β Ori. Rigel is the brightest and most massive component – and the eponym – of a star system of at least four stars that appear as a single blue-white point of…

Acetic acid, systematically named ethanoic acid, is an acidic, colourless liquid and organic compound with the chemical formula CH3COOH. Acetic acid is the active component of vinegar. Historically, vinegar was produced from the third millennium BCE, making acetic acid likely the first acid to be produced in large quantities.

The Hercules–Corona Borealis Great Wall (HCB) or simply the Great Wall or the Great Gamma-Ray Burst Wall is a putative galaxy filament that, if confirmed, would be one of the largest known structures in the observable universe, measuring approximately 10 billion light-years in length, or ~10.8% the length of the observable universe. This…

Laboratory glassware is a variety of equipment used in scientific work, traditionally made of glass. Glass may be blown, bent, cut, molded, or formed into many sizes and shapes. It is commonly used in chemistry, biology, and analytical laboratories. Many laboratories have training programs to demonstrate how glassware is used and to…

Uranus is the seventh planet from the Sun. It is a gaseous cyan-coloured ice giant. Most of the planet is made of water, ammonia, and methane in a supercritical phase of matter, which astronomy calls "ice" or volatiles. The planet's atmosphere has a complex layered cloud structure and has the lowest minimum temperature of all the Solar…

Technetium is a chemical element; it has symbol Tc and atomic number 43. It is the lightest element whose isotopes are all radioactive. Technetium is one of only two radioactive elements both preceded and succeeded in the periodic table by elements with stable forms, the other being promethium. All available technetium is produced as a…

The Chandrasekhar limit is the maximum mass of a stable white dwarf star. These stars resist gravitational collapse primarily through electron degeneracy pressure, compared to main sequence stars, which resist collapse through thermal pressure. The Chandrasekhar limit is the mass above which electron degeneracy pressure in the star's…

Silicate perovskite is either (Mg,Fe)SiO3 or CaSiO3 when arranged in a perovskite structure. Silicate perovskites are not stable at Earth's surface, and mainly exist in the lower part of Earth's mantle, between about 670 and 2,700 km depth. They are thought to form the main mineral phases of the lower mantle, together with ferropericlase.

The term Great Year has multiple meanings. In scientific astronomy, it refers to the time required for the equinoxes to complete one full cycle around the ecliptic, a period of approximately 25,800 years. According to Ptolemy, his teacher Hipparchus discovered this phenomenon by comparing the position of the vernal equinox against the…

Deoxyribonucleic acid is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses. DNA and ribonucleic acid (RNA) are nucleic acids. Alongside proteins,…

Laki or Lakagígar is a volcanic fissure in the western part of Vatnajökull National Park, Iceland, not far from the volcanic fissure of Eldgjá and the small village of Kirkjubæjarklaustur. The fissure is properly referred to as Lakagígar, while Laki is a mountain that the fissure bisects. Lakagígar is part of a volcanic system centered…

In biochemistry, a ligase is an enzyme that can catalyze the joining (ligation) of two molecules by forming a new chemical bond. This is typically via hydrolysis of a small pendant chemical group on one of the molecules, typically resulting in the formation of new C-O, C-S, or C-N bonds. For example, DNA ligase can join two complementary…

Proxima Centauri is the nearest star to Earth after the Sun, located 4.25 light-years away in the southern constellation of Centaurus. Discovered in 1915 by Robert Innes, it is a small, low-mass star, too faint to be seen with the naked eye, with an apparent magnitude of 11.13. Proxima Centauri is a member of the Alpha Centauri star…

Dubnium is a synthetic chemical element; it has symbol Db and atomic number 105. It is highly radioactive: the most stable known isotope, dubnium-268, has a half-life of about 16 hours. This greatly limits extended research on the element.

In chemistry and quantum mechanics, the spin quantum number is a quantum number that describes the intrinsic angular momentum of an electron or other particle. It has the same value for all particles of the same type, such as s = ⁠1/2⁠ for all electrons. It is an integer for all bosons, such as photons, and a half-odd-integer for all…

Sea slug is a common name for some marine invertebrates with varying levels of resemblance to terrestrial slugs. Most creatures known as sea slugs are gastropods, i.e. they are sea snails that, over evolutionary time, have either entirely lost their shells or have seemingly lost their shells due to having a significantly reduced or…

In biochemistry, chemosynthesis is the biological conversion of one or more carbon-containing molecules and nutrients into organic matter using the oxidation of inorganic compounds or ferrous ions as a source of energy, rather than sunlight, as in photosynthesis. Chemoautotrophs, organisms that obtain carbon from carbon dioxide through…

The Andromeda Galaxy is a barred spiral galaxy and is the nearest major galaxy to the Milky Way. It was originally named the Andromeda Nebula and is cataloged as Messier 31, M31, and NGC 224. Andromeda has a D25 isophotal diameter of about 46.56 kiloparsecs (152,000 light-years) and is approximately 765 kpc (2.5 million light-years) from…

Halley's Comet is the only known short-period comet that is consistently visible to the naked eye from Earth, appearing roughly every 75–76 years, though with the majority of recorded apparitions occurring after 75–77 years. It last appeared in the inner parts of the Solar System in 1986 and will next appear in mid-2061. Officially…

James Clerk Maxwell was a Scottish physicist and mathematician who was responsible for the classical theory of electromagnetic radiation, which was the first theory to describe electricity, magnetism and light as different manifestations of the same phenomenon. Maxwell's equations for electromagnetism achieved the second great…

Friedrich Wöhler FRS(For) HonFRSE was a German chemist known for his work in both organic and inorganic chemistry, being the first to isolate the chemical elements beryllium and yttrium in pure metallic form. He was the first to prepare several inorganic compounds, including silane and silicon nitride.

A mitochondrion is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is used throughout the cell as a source of chemical energy. They were discovered by Albert von Kölliker in 1857…