Eureka! Try This Quiz on Scientific Discoveries

Although the first recorded observation of Uranus was in 1690, scientists assumed it was a star until 1781, when British astronomer William Herschel suggested that it was more likely a planet. As a reward for his discovery, Herschel was made the Court Astronomer to King George III, and honored his patron by naming the new planet after the king. The planet was known as Georgium Sidus, Latin for "George's star," for about 70 years before being renamed Uranus in 1850.

On April 12, 1955, the polio vaccine developed by American virologist Jonas Salk was determined to be safe and effective by the Poliomyelitis Vaccine Evaluation Center at the University of Michigan. Within 25 years, a disease that had caused an average of 15,000 paralysis cases in the 1950s was essentially eliminated throughout the U.S. At the end of his career, Salk dedicated his efforts to the search for an AIDS vaccine, before his death in 1995.

American astronomer Edwin Hubble completely changed the way we view outer space. While looking through his 100-inch telescope at Mount Wilson in Southern California, Hubble noticed that the “Andromeda Nebula” (now called the Andromeda galaxy) had stars very similar to our galaxy, deducing that it was an entirely different galaxy. Hubble also proved that objects that were previously labeled as dust, clouds, and gas were actually more galaxies. Because of his contributions to astronomy, the Hubble Space Telescope was named after him.

The pH scale was created in the early 20th century by Danish chemist S.P.L Sørensen, the director of the department of chemistry at the Carlsberg brewery. Brewery founder J.C. Jacobsen established the Carlsberg Laboratory in 1876 to study the science of malting, brewing, and fermentation. At the lab, Sørensen examined the acidity of different compounds and decided that a new system was needed to better express such properties. In 1909, he introduced the pH scale, which indicates how acidic or basic a substance is, measuring pH on a scale from 0 to 14.

Throughout her career as an astronomer, Vera Rubin was fascinated by how galaxies moved. In the 1970s, while researching galaxy rotation with astronomer Kent Ford, she observed a strange acceleration at the edges of the Andromeda galaxy. Though she didn't realize it at the time, she had observed the movement of dark matter, the substance that makes up an estimated 84% of our universe.

When German miners first discovered the element we now call cobalt, they didn’t know what they’d found. The element superficially resembled silver, and was present in silver mines, but it didn’t smelt like silver at all. It also had noxious effects on the miners' health, releasing toxic gases during the smelting process. The miners decided the material was bewitched by mischievous, mountain-dwelling earth spirits from local folklore, called “kobold,” and they named the ore after these creatures.

When someone discovers a new chemical element, they are granted the honor of naming the substance. So when French scientist Paul-Émile Lecoq de Boisbaudran discovered gallium in 1875, he decided to name it after his native country. Lecoq said that he was patriotically inspired by the Latin name for France, “Gallia,” though it likely didn’t hurt that his own name, Lecoq, is “Gallus” in Latin.

Though all he had was a telescope, Italian astronomer Galileo Galilei was an early pioneer of space exploration. He made many important discoveries, including the four largest moons of Jupiter (Io, Europa, Ganymede, and Callisto), now called the Galilean moons. He also discovered that the Milky Way was made up of stars, and was the first to see lunar craters, sunspots, the phases of Venus, and Saturn’s rings.

In 1948, psychologist B.F. Skinner gave eight hungry pigeons food every 15 minutes, and noticed that between feedings, six of the birds ritualistically repeated the behavior they happened to be doing when the food first "miraculously" appeared — like bobbing their heads or turning counterclockwise. Skinner concluded that the pigeons considered their random behavior to be a cause of the food.

Decades after Uranus was discovered in 1781, scientists started to suspect that another planet existed beyond it, and began looking for answers. Astronomers Urbain Le Verrier and Johann Galle are credited with finally discovering Neptune in 1846, with Galle using Le Verrier's mathematical calculations to become the first person to actually observe the planet through a telescope.

In the 1940s, engineer Percy Spencer was multitasking — experimenting with a powerful magnetic-electric hybrid known as a magnetron, while also preparing to eat a snack. When he put his hand in his pocket, however, he quickly realized that his peanut cluster was a “gooey, sticky mess.” Spencer experimented with the magnetron’s potential for quickly warming foods with an egg (which exploded in his face) and popcorn (which he shared with the rest of the office). A year later, in 1947, the first microwave oven hit the market.

We have the English physicist Isaac Newton to thank for the seven colors of the rainbow. In the 1660s, Newton undertook an experiment in which he projected white light through a prism onto a wall and had a friend mark the boundaries between the colors. He determined there were seven colors, in part based on his preconceived notion that the colors of the rainbow matched the notes of a musical scale.

In 1928, Scottish scientist Alexander Fleming discovered that some bacteria he had been culturing was accidentally killed by a mold called penicillium rubens. After further experiments, Fleming was able to distill the antibacterial properties of the fungus and began using it in medicine. Since then, penicillin has been most commonly made through chemical synthesis.

Prior to the discovery of insulin, patients diagnosed with type 1 diabetes had a very limited life span. The use of insulin to treat diabetes was discovered in 1921 by scientists Sir Frederick Banting, Charles Best, and J.J.R. Macleod at the University of Toronto. The team was awarded a Nobel Prize in medicine in 1923.

During some experiments with cathode rays, scientist Wilhelm Röntgen noticed a glimmer of light on a fluorescent screen across the room. Further examination revealed the phenomenon to be a new kind of ray, which Röntgen called the "X-ray" because it was still a new and unknown concept. That same year, 1895, Röntgen took the first X-ray image, which featured the bones in his wife's hand.

Swedish scientist and mathematician Andres Celsius created what he called the centigrade scale in 1742. He coined the name based on the Latin words for 100, "centum," and step, or "gradus." Used in the majority of countries in the world, the scale considers the freezing point of water to be zero degrees, and the boiling point of water at sea level to be 100 degrees. The scale was renamed to honor Celsius himself amid a push for standardization in 1948.

For her studies on radiation, Marie Curie was awarded the 1903 Nobel Prize in Physics, and then in 1911, she earned the Nobel Prize in Chemistry for her discoveries of the elements radium and polonium. These prizes made her the first woman to win a Nobel Prize and the first person to win two Nobels.

Before writing his book "On the Origin of Species," Charles Darwin went on a trip as a naturalist aboard the HMS Beagle. The crew stopped at the Galápagos Islands in the 1830s, and Darwin was amazed by the different species of finches that he believed were all descendants of the same lineage. Darwin would lay that theory out in his book and change the way people thought about nature and themselves.

In June 1752, Benjamin Franklin flew a kite during a thunderstorm as an experiment to demonstrate the electrical properties of lightning. While lightning never actually struck the kite, it did pick up an ambient charge thanks to a key he tied to it. The charge was collected in a Leyden jar, which could then be used at another time, showing the connection between lightning and electricity.

In 1953, scientists Francis Crick, James Watson, and Rosalind Franklin described the molecular structure of DNA as a "double helix." The structure is essentially two spirals that coil around each other and are connected by nucleotide interactions, carrying genetic instructions for the growth and development of organisms. For their discovery, Crick and Watson won the 1962 Nobel Prize in physiology.