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Science

How can the sky be blue one day and stormy the next? Why do heavy objects tend to fall downwards when dropped? How are birds able to fly (and why can’t I do the same?)? Human beings have long been curious about the world in which we live, striving to identify connections among the phenomenons we witness and to understand how it all works. The field of science has developed over many centuries as a way of studying and understanding the world, beginning with the primitive stage of simply noting important regularities in nature and continuing through the rise of modern science. The modern-day sciences cover a vast range of fields, including biology, chemistry, meteorology, astronomy, physics, and much more.
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Featured content, May 19, 2020

Transit of Mercury
On Monday, May 9, 2016, the planet Mercury will cross the face of the Sun.
Spotlight / Science
Time lapse photo showing transit of Mercury across Sun's disk, November 15, 1999. Image from the Transition Region and Coronal Explorer (TRACE) satellite.
Louis Pasteur’s Contributions to Science
Learn more about this influential scientist’s work.
Companion / Science
Louis Pasteur in his laboratory, painting by Albert Edelfelt.
The Arctic’s Seed-Filled Doomsday Fortress
Our crop diversity is safe in Svalbard.
#WTFact / Science
Svalbard Global Seed Vault, Scandinavia
Do Hyenas Really Laugh?
It sounds like a human giggle or even maniacal laughter, but are hyenas really laughing?
Demystified / Science
Spotted hyena (Crocuta crocuta) family, Botswana
Titanosaurs: 8 of the World's Biggest Dinosaurs
The largest land animals of all time.
List / Science
illustration of the walking titanosaurus, Patagotitan mayorum
Star
Star, any massive self-luminous celestial body of gas that shines by radiation derived from its internal energy sources.…
Encyclopedia / Science
open cluster NGC 290
Space tourism
Space tourism, recreational space travel, either on established government-owned vehicles such as the Russian Soyuz and the…
Encyclopedia / Science
Charles Simonyi, Gennady Padalka, and Michael Barratt
Space exploration
Space exploration, the investigation, by means of crewed and uncrewed spacecraft, of the reaches of the universe beyond Earth’s…
Encyclopedia / Science
astronaut outside the International Space Station

Science Quizzes

Ice cubes on white background. (frozen; freeze; ice cube)
Ice, Water, Vapor: Fact or Fiction?
Does water contract when it freezes? Is water the most common element on Earth? From snowmelts to freezing points, let your…
Lightning
Lightning: Fact or Fiction?
Are skyscrapers safe from lightning strikes? Do ice crystals help in the production of lightning? Learn more about the most…
spruce. A young spruce tree grows on a bank of a forest of similar conniferous trees, Alberta, Canada. logging, forestry, wood, lumber
Trees: Fact or Fiction?
How many leaves are produced on an elm tree each year? Do growth rings really tell you the age of a tree? From deforestation…
Paper. Piles of white office paper stacked and tied with red string.
Paper: Fact or Fiction?
What is the most frequently used paper size? How many sheets of paper can a single tree produce? From reams to quires, learn…
electric power. High-voltage transmission lines carrying electricity. Sunset and electric power lines. Energy, sundown, power supply
Energy: Fact or Fiction?
Can microbes provide energy? How much energy do video games use? From the human body to radar, learn more about energy in…
M18 is a small star cluster in the constellation Sagittarius.
Constellations: Fact or Fiction?
Is Hydra the largest constellation in the night sky? Are some stars made of diamonds? From Alpha Centauri to the Sun, learn…
M101 (NGC 5457, The Pinwheel Galaxy). Hubble Space Telescope image of face-on spiral galaxy Messier 101 (M101). Largest most detailed photo of a spiral galaxy that has ever been released from Hubble. Created from 1994-2003
Galaxies: Fact or Fiction?
Does the word "galaxy" come from the Greek word for milk? Can galaxies unite? Learn more about galaxies by taking this star-studded…
Hurricane. Storm on Phuket Island, Phuket Province, Tropical Climate, hurricane Homepage blog 2011, science and technology weather storm tropical cyclone
Blowing in the Wind: Fact or Fiction?
Are there winds in space? Are winds caused by waves in the ocean? From westerlies to hurricanes, learn more about wind in…
ore. iron ore minerals, rock, metal, metallic iron
Metals: Fact or Fiction?
Is iron the most abundant metal in the Earth’s crust? Is potassium a hard metal? Open this treasure-trove of a quiz that’s…
greylag. Flock of Greylag geese during their winter migration at Bosque del Apache National Refugee, New Mexico. greylag goose (Anser anser)
Biology Bonanza
What does the word "migration" mean? How many sets of legs does a shrimp have? From poisonous fish to biodiversity, learn…
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Science Subcategories

subcategory placeholder Astronomy
Human beings have always been fascinated by the celestial sphere above, whose twinkling lights have inspired many theories and artistic endeavors. Study of the solar system has provoked more than just peaceful meditation, however; a major controversy among astronomers arose in the 16th century when Copernicus publicly championed heliocentrism, a Sun-centric model of the solar system that was in direct opposition to Ptolemy's Earth-centered model, which had been generally accepted from the 2nd century CE onward. But humankind's fascination with the world beyond Earth has also led to some landmark moments in history, as when space exploration took a giant step forward with the advent of technology that allowed humans to travel to the Moon and to build spacecraft capable of exploring the rest of the solar system and beyond.
Articles
Chordate Biology
If it’s alive, biology will define it, study it, observe all its functions, follow its vital processes, and interact with it, all in order to understand the life that animates it. In one of biology's best-known examples of such studious investigation, Charles Darwin came up with his scientific theory of evolution by natural selection after systematically observing a variety of plants and animals; his work acted as the foundation upon which modern evolutionary theory is built. But biology’s principles also operate within a plethora of other related fields, including biochemistry, biomedicine, biophysics, and microbiology.
Articles
Black girdle-tailed lizard (Cordylus nigra). Birds, Reptiles & Other Vertebrates
Although it can be hard to imagine that a peacock and a crocodile have much of anything in common, these animals are actually descendants of the same prehistoric vertebrates. Birds are thought to have descended from carnivorous dinosaurs that began growing feathers by the Late Jurassic Period; thus, birds are technically one lineage of reptiles. This evolutionary link highlights the way in which seemingly incongruous creatures can, in fact, share a common ancestor (though that doesn't mean that we should expect waterfowl and crocodiles to become friends anytime soon).
Articles
A deep-sea jellyfish of the genus Crossota collected from the Canadian Basin in the Arctic Ocean. Bugs, Mollusks & Other Invertebrates
Some insects are so displeasing to humans that the word "bug" has come to be used as a verb meaning "to bother or annoy." Yet, in addition to being critically important—because they naturally recycle decaying matter—in maintaining balance within the food chain, bugs can also be fascinating creatures, whether in regard to the water strider's ability to run across the surface of water or in regard to assassin bugs' varied and creative means of catching and killing their prey. Mollusks, another group of invertebrates, get less of a bad rap. Their ranks include nearly 100,000 described species of soft-bodied animals that are usually wholly or partly enclosed in a calcium carbonate shell; examples include snails, clams, oysters, squids, and octopuses.
Articles
periodic table Chemistry
How do you use raw plant materials to manufacture a best-selling perfume? How do you engineer household products that are compliant with environmentally-oriented guidelines? The answers to these questions require an understanding of the laws of chemistry, the science that deals with the properties, composition, and structure of elements and compounds, as well as the transformations that such substances undergo and the energy that is released or absorbed during those processes. Chemistry is also concerned with the utilization of natural substances and the creation of artificial ones. Over time, more than 8,000,000 different chemical substances, both natural and artificial, have been characterized and produced. Chemistry's vast scope comprises organic, inorganic, physical, analytical, and industrial chemistry, along with biochemistry, environmental chemistry, medicinal chemistry, and much more. Through the dedicated efforts of people such as Robert Boyle, Dmitri Mendeleev, John Dalton, Marie Curie, and Rosalind Franklin, the field of chemistry has led to exciting innovations as well as crucial advances in our understanding of how the world functions, starting with just the miniscule and unassuming atom.
Articles
faux amphibolite Earth Science, Geologic Time & Fossils
Planet Earth has billions of years of history, from the time when it was an inhospitable ball of hot magma to when its surface stabilized into a variety of beautiful and diverse zones capable of supporting many life-forms. Many are the species that lived through the various geologic eras and left a trace of their existence in the fossils that we study today. But Earth is never done settling, as we can see from the earthquakes, tsunamis, volcanic eruptions, and other phenomena manifested in Earth’s crust, oceans, and atmosphere.
Articles
Grinnell Glacier shrinkage Environment
Biological diversity is key to a healthy ecosystem, whether it’s a small biological community or the global biosphere. Ecology, which studies the relationships between organisms and their environment, is an invaluable science that helps us understand what allows an ecological community to thrive.
Articles
Killer whale (Orcinus orca). Mammals
These are the animals to which humans tend to relate the most, perhaps because aspects of their behavior can sometimes resemble the way that we ourselves behave. The protective instinct of a mother bear, the gamboling way that kittens play, and the loyalty displayed by a dog are all traits that we can identify with in the course of our own lives. Mammals are well-equipped to handle different climates and biomes because of their ability to regulate their own body temperatures and internal environment, both in excessive heat and aridity and in severe cold.
Articles
An illustration of the difference between average and instantaneous rates of changeThe graph of f(t) shows the secant between (t, f(t)) and (t + h, f(t + h)) and the tangent to f(t) at t. As the time interval  h approaches zero, the secant (average speed) approaches the tangent (actual, or instantaneous, speed) at (t, f(t)). Mathematics
Although stock portrayals of mathematicians often involve a studious person standing in front of a chalkboard that's covered with mind-bogglingly complex scrawled mathematical problems (call it the "Good Will Hunting" effect), the chaotic-looking equations may obscure the fact that mathematics is, at its heart, a science of structure, order, and relation that deals with logical reasoning and quantitative calculation. There's a method to all that madness! The history of mathematics can be traced back to ancient Mesopotamia, whose clay tablets revealed that the level of mathematical competence was already high as early as roughly the 18th century BCE. Over the centuries, mathematics has evolved from elemental practices of counting, measuring, and describing the shapes of objects into a crucial adjunct to the physical sciences and technology.
Articles
photosynthesis Plants
Life on Earth owes much to plants. The vast majority of plants carry out photosynthesis to transform light energy into chemical energy, which is the way that virtually all energy in the biosphere becomes available to living things (including us humans). As photosynthetic organisms, plants occupy the base of Earth's food webs and are consumed directly or indirectly by all higher life-forms, thereby functioning as the major source of food for humans and other animals. Plants' photosynthetic activity also produces the air that we breathe: almost all the oxygen in the atmosphere is due to the process of photosynthesis. Still not convinced about the merits of plants? Consider the fact that many plants not only serve up crucial nutrients and breathable air but also look good doing it. Many plants are admired for their striking aesthetic qualities, and flowers such as tulips, lilies, sunflowers, and daisies beautify fields, gardens, windowsills, and bouquets the world over. Plants are also a primary source of consumer goods, such as building materials, textile fibers, and pharmaceuticals.
Articles
Acoustics Physics
What’s the matter? The matter is our whole observable universe—with that material substance that constitutes it—and it is the subject of study of physics. The laws that govern motion observed by Newton, the gravitational force that regulates the progress of all celestial bodies, the interaction between subatomic particles, and the nuclear engineering that created the atomic bomb are examples of what this important discipline is all about. Minkowski’s space-time concept, which reformulated Einstein’s special theory of relativity, has bridged physics with philosophy in a conversation that has fascinated the modern concept of physics.
Articles
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