Earth rising over moon's horizon


Century of Science


from ScienceNews

112 Milestones in
Our wild universe

  1. 1910
    1. Continental drift

      Meteorologist Alfred Wegener suggests that Earth’s continents aren’t fixed in place, but drift around the globe.

      Shaking up Earth
    2. Earth’s story

      Geologist Arthur Holmes publishes The Age of the Earth, presenting the first complete geologic timescale and arguing for using radioactive materials as geologic clocks.

      Shaking up Earth
  2. 1920
    1. professional photos of Edgar Allen and Edward A. Doisy

      From left: NLM/NIH (CC BY 2.0); Washington Univ., NLM/NIH

      Estrogen found

      Two scientists at Washington University of St. Louis, Edgar Allen and Edward Doisy, first isolated estrogen in experimental mice and found that it was produced in the ovaries.

      The mystery of reproduction
    2. Human EEG

      German psychiatrist Hans Berger reports the first human electroencephalogram, or EEG.

      Our brains, our futures
  3. 1930
    1. Discovery of the neutron

      Physicist James Chadwick discovers an electrically neutral particle, the neutron, contained within atomic nuclei.

      Cracking the atom
    2. Positron found

      Images from physicist Carl Anderson’s cloud chamber reveal a positively charged particle with a mass equivalent to the electron: a positron.

      Cracking the atom
    3. Jansky and his rotating radio antenna

      NRAO, AUI, NSF

      Radio astronomy

      Karl Jansky’s discovery of a shortwave radio hiss coming from the Milky Way’s heart is widely publicized, marking the beginning of radio astronomy. Jansky is shown here with his rotating radio antenna.

      Our wild universe
    4. Dark matter

      Fritz Zwicky examines galaxies in the Coma cluster and determines that there is unseen mass, what scientists now call “dark matter.”

      Our wild universe
    5. historical image of Charles Richter

      New York Public Library/Science Source

      Shaking scale

      The Richter scale is proposed by seismologist Charles Richter (shown) to compare the magnitude of different earthquakes. The more accurate moment magnitude scale is now used for most earthquakes.

      Shaking up Earth
    6. Inner core

      Seismologist Inge Lehmann discovers that Earth has a solid inner core, distinct from its molten outer core.

      Shaking up Earth
    7. Science Source

      Nuclear fission

      In a discovery that portends the possibility of atomic bombs, Otto Hahn (right) and Fritz Strassmann report evidence that uranium atoms produce barium when bombarded with neutrons. As explained by their collaborator Lise Meitner (left) and her nephew Otto Frisch, this is fission, the splitting of atoms.

      Cracking the atom
  4. 1940
    1. Shell model of the nucleus

      Physicists Maria Goeppert Mayer and J. Hans D. Jensen develop a theory of the nucleus as composed of shells of protons and neutrons. It explains why nuclei with certain “magic numbers” of protons and neutrons are more stable.

      Cracking the atom
    2. Manhattan Project gets into gear

      With the formation of the Manhattan Engineer District, the United States kick-starts a massive project to build an atomic bomb, which employed more than 120,000 people at its peak.

      Cracking the atom
    3. National Nuclear Security Administration, Nevada Site Office/U.S. Dept of Energy

      Dropping the bomb

      In July, the United States tests the atomic bomb in the New Mexico desert. In August, the U.S. drops two bombs on Japan, killing more than 100,000 people and hastening the end of World War II.

      Cracking the atom
    4. Dynamo theory

      Physicist Walter M. Elsasser and geophysicist Edward Bullard separately propose between 1946 and 1949 that Earth’s magnetic field is a self-sustaining dynamo generated by the movement of fluid in the liquid outer core, which produces an electric current.

      Shaking up Earth
    5. x-ray of a skull

      J. L. Pool/J. Am. Geriatr. Soc 1954

      Electrodes for Parkinson’s

      J. Lawrence Pool is the first to implant electrodes into a woman with Parkinson’s disease.

      Our brains, our futures
    6. Neurons firing, wiring

      Canadian psychologist Donald Hebb publishes his account of how neurons reinforce each other’s activity, a description that’s now shorthanded, “fire together, wire together.”

      Our brains, our futures
  5. 1950
    1. UC San Diego School of Medicine

      Hippocampus and memory

      A patient known as H.M. undergoes surgery to remove his hippocampus, later revealing the role that the brain structure plays in memory. Studies of his postmortem brain (shown) complicated the picture.

      Our brains, our futures
    2. photo of Canyon Diablo meteorite

      Geoffrey Notkin, Aerolite Meteorites of Tucson/Wikimedia Commons (CC BY-SA 2.5)

      Age of Earth

      Geochemist Clair Patterson sets the age of the Earth at 4.550 billion years, relying on ages of meteorites (including the Canyon Diablo meteorite, shown) that formed around the same time.

      Shaking up Earth
    3. Neutrino found

      Scientists detect the neutrino, an electrically neutral subatomic particle released in radioactive decay and other reactions. It had once been thought to be undetectable.

      Cracking the atom
    4. Parity violation

      Particles that are mirror images — those with opposite “handedness” or orientation of their spin — don’t necessarily behave identically. Chien-Shiung Wu and colleagues report the discovery of this phenomenon, called parity violation, in decays of cobalt-60 atoms.

      Cracking the atom
    5. Vision insight

      David Hubel and Torsten Wiesel illuminate the visual system in the cat, opening up an area of inquiry for how brain systems handle information from the senses.

      Our brains, our futures
  6. 1960
    1. Birth control pill

      The U.S. Food and Drug Administration approves the first oral contraceptive, soon known simply as “the pill.”

      The mystery of reproduction
    2. Hot spots

      Geophysicist J. Tuzo Wilson suggests that volcanic island chains form as plates move over upwellings of magma in the mantle.

      Shaking up Earth
    3. black and white photo of Arno Penzias (left) and Robert Wilson (right)

      Keystone Press/Alamy Stock Photo

      Background radiation

      Arno Penzias (left) and Robert Wilson (right) discover the cosmic microwave background radiation, the relic radiation left over from the Big Bang.

      Our wild universe
    4. black and white photo of Beatrice Mintz

      Smithsonian Institution/Flickr

      Four-parent mouse

      Beatrice Mintz creates a mouse with two mothers and two fathers to demonstrate which parent’s genetic contribution ended up in which region of the body.

      The mystery of reproduction
    5. Strong connections

      Norwegian physiologist Terje Lømo observes that connections between nerve cells strengthen with use, a core principle of neuroscience called long-term potentiation.

      Our brains, our futures
    6. Harry Whittington looking at fossils

      Geological Survey of Canada

      Wonderful life

      Harry Whittington (shown) leads an expedition to Canada’s Burgess Shale, identifying a riot of new and unusual forms of animal life and boosting studies into the Cambrian explosion.

      Shaking up Earth
    7. First pulsar

      The first pulsar — stellar objects emitting beams of radiation that look from Earth like pulses — is discovered by Jocelyn Bell Burnell.

      Our wild universe
  7. 1970
    1. Cell division

      Studying baker’s yeast, geneticist Leland H. Hartwell identifies genes that regulate how cells divide as well as proteins that halt division if a cell’s DNA is damaged.

      The mystery of reproduction
    2. Quarks and the November revolution

      Two teams of physicists find a new subatomic particle, the J/psi, which, it soon became clear, could be explained only by a new type of quark, the charm quark. This discovery and others during the period, known as the November revolution, quelled lingering doubts that quarks were real constituents of larger particles such as protons, neutrons and the J/psi.

      Cracking the atom
    3. Lunar origins

      Astronomers William Hartmann and Donald Davis propose in 1975 the Giant Impact Hypothesis, suggesting the moon formed out of material ejected from Earth after a large collision. Space scientist Alastair Cameron and astronomer William Ward developed the same idea independently, proposing it in 1976.

      Shaking up Earth
    4. Milankovitch cycles

      Scientists find that Earth’s ice ages over the last 500,000 years correlate to three different orbital variations — cycles lasting about 23,000 years, 42,000 years (now said to be 41,000) and 100,000 years, confirming a hypothesis proposed decades earlier by astronomer Milutin Milankovitch.

      Shaking up Earth
    5. Body planning

      Work reported by Edward Lewis in 1978 and Christiane Nüsslein-Volhard and Eric Wieschaus in 1980 reveals which genes control early embryonic development in fruit flies. The discoveries help explain congenital defects and lead to research on similar genes that determine the human body plan.

      The mystery of reproduction
    6. black and white photo of Vera Rubin

      AIP Emilio Segrè Visual Archives, Rubin Collection

      Dark matter levels up

      Vera Rubin (shown), Kent Ford and Norbert Thonnard measure the rotation rates of stars in outer parts of galaxies, strongly implying the existence of dark matter.

      Our wild universe
  8. 1980
    1. Cosmic collision

      Luis Alvarez and Walter Alvarez publish a report saying that a large space rock hitting Earth was responsible for the mass extinction event 66 million years ago that killed off all nonbird dinosaurs. The father-son team proposed the idea at American Geophysical Union’s annual meeting the year before.

      Shaking up Earth
    2. Alzheimer’s discovery

      George Glenner and Caine Wong discovered a “novel cerebrovascular amyloid protein.” That was amyloid-beta, the key component of plaques in the brains of people with Alzheimer’s disease.

      Our brains, our futures
    3. schematic diagram of the nervous system of C. elegans

      J.G. White et al/Proceedings of the Royal Society B 1986

      Worm connectome

      Scientists trace the wiring diagram of the nervous system of a C. elegans worm.

      Our brains, our futures
    4. Walls and voids

      Margaret Geller, John Huchra and Valérie de Lapparent map a section of the observable universe, revealing a structure that encompasses large walls and giant voids.

      Our wild universe
    5. Great ocean conveyor

      Geochemist Wallace Broecker describes a global system of ocean currents that transports heat and salt between surface and deep waters and around the globe, influencing regional climates. 

      Shaking up Earth
    6. Novel antidepressant

      The drug fluoxetine, or Prozac, received approval from the U.S. Food and Drug Administration as a treatment for major depression.

      Our brains, our futures
    7. Genetic screening

      Alan Handyside of London’s Hammersmith Hospital is able to check an embryo for genetic defects before implanting it into a mother’s uterus. This testing, known as preimplantation genetic diagnosis or PGD, enables parents carrying a genetic or chromosomal defect to avoid passing it to their children.

      The mystery of reproduction
  9. 1990
    1. illustration of the hubble space telescope


      Hubble launch

      NASA launches the Hubble Space Telescope (shown), one of the sharpest eyes to ever peer into the cosmos.

      Our wild universe
    2. Mount Pinatubo erupting

      Hoa-Qui/Science Source

      Pinatubo’s shade

      A powerful eruption from the Philippines’ Mount Pinatubo (shown) ejects millions of tons of sulfur dioxide into the stratosphere, temporarily cooling the planet.  

      Shaking up Earth
    3. Screengrab of SN news of the week on COBE

      Science News

      Signs of inflation

      Cosmologists detect temperature fluctuations in the cosmic microwave background, variations that correspond to ripples in the density of matter shortly after the Big Bang, as expected from inflation.

      Our wild universe
    4. First cloned mammal

      Dolly the Sheep is the first mammal cloned from the DNA of an adult mammal. Ian Wilmut and Keith Campbell of the Roslin Institute transferred the nucleus of an adult mammary gland cell into an egg cell, showing that adult DNA can be reprogrammed to grow a new organism.

      The mystery of reproduction
    5. Neutrinos have mass

      Physicists discover that neutrinos, long thought to be massless, have a tiny amount of mass. The find raises a slew of still-unanswered questions, whether neutrinos are their own antiparticles, for example, or whether the particles can help explain the scarcity of antimatter in the universe.

      Cracking the atom
    6. photo of Alan Trounson

      Tim Grainger/Monash Univ./Flickr (CC BY-NC-ND 2.0)


      Australian researcher Alan Trounson reports successful vitrification, a method that freezes eggs so rapidly that no crystals can form. The technique boosts the success rate for using frozen eggs in assisted reproduction.

      The mystery of reproduction
  10. 2000
    1. an electrode with a dime behind it for scale

      Brain implant

      An implanted grid of electrodes called BrainGate allows a paralyzed man to check his e-mail and play games with his brain activity alone.

      Our brains, our futures
    2. Quark-gluon plasma

      Physicists at Brookhaven National Laboratory smash nuclei of gold atoms together to recreate the phase of matter thought to have existed in the early moments of the universe. The quark-gluon plasma is a hot, dense soup of quarks intermingling freely with gluons, which under normal conditions bind quarks into larger particles like protons and neutrons.

      Cracking the atom
    3. Bullet Cluster image


      Dark matter in space

      By studying an intergalactic collision (which formed the Bullet Cluster, shown), researchers report compelling evidence of dark matter’s presence in space.

      Our wild universe
  11. 2010
    1. Tohoku-oki quake

      A magnitude 9.0 earthquake in Japan and the tsunami it spawned kill more than 15,000 people and damaged reactors at the Fukushima power plant, triggering the worst nuclear disaster since Chernobyl in 1986.

      Shaking up Earth
    2. Fukushima accident

      After an earthquake and tsunami, reactors at the Fukushima Daiichi Nuclear Power Station lost power and cooling, resulting in partial meltdowns, explosions and releases of radioactive material. Over 100,000 people were evacuated as a result.

      Cracking the atom
    3. © CERN (CC BY-SA 4.0)

      Higgs is found

      Physicists at CERN near Geneva report discovery of the final particle predicted by the standard model, the Higgs boson. Its existence confirms scientists’ beliefs about how fundamental particles obtain mass.

      Cracking the atom
    4. CRISPR baby

      Chinese scientist Jiankui He uses CRISPR/Cas9 to create the first gene-edited babies — twin girls — to reduce their risk of contracting HIV. His actions lead to the formation of an international commission on the clinical use of gene editing.

      The mystery of reproduction