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, October 28, 2020

Why Is the Platypus a Mammal?
The platypus has a bill and webbed feet like a duck and venom like a snake. And it lays eggs. Despite all of this, it’s classed...
Companion / Science
Platypus (Ornithorhynchus anatinus) swimming on the surface of a creek. Water Australia mammal monotreme
The Oldest Human Ancestor
In 2017, scientists identified fossils of a primitive sea creature they say is the oldest known ancestor of a wide range...
#WTFact / Science
Artist's reconstruction of Saccorhytus coronarius, based on the original fossil finds. The actual creature was probably no more than a millimeter in size.
Why Do Cats Hate Water?
Find out why cats aren’t exactly known as keen swimmers.
Demystified / Science
Tabby cat mammal animal feline
Anthropocene Epoch
Anthropocene Epoch, unofficial interval of geologic time, making up the third worldwide division of the Quaternary Period...
Encyclopedia / Science
Anthropocene Epoch
Chemical bonding
Chemical bonding, any of the interactions that account for the association of atoms into molecules, ions, crystals, and other...
Encyclopedia / Science
crystal bonding
Scientific theory
Scientific theory, systematic ideational structure of broad scope, conceived by the human imagination, that encompasses a...
Encyclopedia / Science
Radiation
Radiation, flow of atomic and subatomic particles and of waves, such as those that characterize heat rays, light rays, and...
Encyclopedia / Science
Figure 1: Energy states in molecular systems (see text).

Science Quizzes

hot flying sparks, loud firework exploding, pyrotechnic gunpowder sulfur blast, explosive
The Stuff That Things Are Made Of
Gunsmoke was a popular television program made up of actors, but do you know what gunpowder is made...
View of the Andromeda Galaxy (Messier 31, M31).
The Night Sky: Galaxies and Constellations
In what constellation is Sirius found? How many galaxies are there in the universe? From Orion’s beard to the Milky Way,...
Band of horses in the saltmarsh at Assateague Island National Seashore, Maryland, Virginia, NPS. Assateague's wild horses are actually feral animals, descendants of domestic animals that have reverted to a wild state.
All About Animals
From the evolution of birds and horses to Earth’s tallest land creature, learn more about wildlife in this zoology quiz.
Three graduated beakers with yellow, blue and gree fluid on white background. Chemistry measurement, science experiment, science demonstration
Measurement Mania
What is a meter? How many grams are in a pound? See if your knowledge "adds up" in this measurements quiz.
Soyuz. The Soyuz TMA-13 spacecraft in flight after takeoff. A Soyuz mission to the International Space Station (ISS) launched from Baikonur, Province of Kazakhstan, October 12, 2008. spaceship, rocket blast off, space travel
Space-Time and Space-Distance
From light-years to Martian years, test your knowledge of the speeds and distances of space objects in this quiz.
human skin. Close-up of age spots and wrinkles on a white male senior's facial skin. complexion, ugly, human face
Human Skin: Fact or Fiction?
Is acne caused by chemical changes in the body? Are differences in skin color related to pigment? Unclog your mental pores...
A few month old newborn human baby with closed eyes naps on a blanket. childhood, cute, sleep, relax, infant, infancy
The Human Experience: Fact or Fiction?
Does human hair grow faster in the summer or in the winter? Are most human babies born on their exact due dates? Learn more...
The Blunted, Bent, False, or Rhomboidal Pyramid, built by Snefru in the 4th dynasty (c. 2575 - 2465 BCE), Dahshur, Egypt. Bent Pyramid of Dahshur, Bent Pyramid at Dahshur, Dashur, Bent Pyramid of King Snefru.
Ancient Life: Fact or Fiction?
From Neanderthals to ancient Egypt, explore early human life in this quiz.
Prism illustration  (light refraction)
Optics: Fact or Fiction?
Does sound travel faster than light? Does each color of light have its own wavelength? Sort fact from fiction--and light...
Rattlesnake. A rattle snake coiled on rock. Rattlesnakes are poisonous snakes that have rattles in their tails. Reptile. Possibly mounted or stuffed taxidermy snake.
Vipers, Cobras, and Boas...Oh My!
What is the world’s longest poisonous snake? To which continent are rattlesnakes native? Learn more about these limbless...
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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
  • Astronomy
  • Great Red Spot
    storm system, Jupiter
  • Mark Kelly and Scott Kelly
    American astronauts
  • 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
  • Snake
    reptile
  • Turtle
    reptile
  • Fish
    animal
  • Mantid (Mantis religiosa). 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
  • Jellyfish
    marine invertebrate
  • Coral
    invertebrate
  • Worm
    animal
  • 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
    subcategory placeholder 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
  • Batodonoides
    fossil mammal genus
  • Hadean Eon
    geochronology
  • Sea level
    Earth science
  • 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
    Meerkat, or suricate (Suricata suricatta). 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
  • Llama
    mammal
  • Elephant
    mammal
  • Wallaby
    marsupial
  • Plot of the cubic equation f(x) = x3 − 3x + 2. The plotted points are where changes in curvature occur. 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
  • Geometry
    mathematics
  • Fractal
    mathematics
  • Trigonometry
  • mandacaru cactus 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
  • Wollemi pine
    tree
  • Rafflesiaceae
    plant family
  • Moss
    plant
  • 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
  • Light
    physics
  • Principles of physical science
  • Solid
    state of matter
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