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Johannes Kepler: first two laws of planetary motion
Johannes Kepler published his first two laws about planetary motion in 1609, having found them by analyzing the astronomical observations of Tycho Brahe.Notably, Kepler had believed in the Copernican model of the solar system, which called for circular orbits, but could not reconcile Brahe's highly precise observations with a circular fit to Mars' orbit (Mars coincidentally having the highest eccentricity of all planets except Mercury). His first law reflected this discovery. -
Galileo Galilei: Sidereus Nuncius: telescopic observations
Sidereus Nuncius is a short astronomical treatise published in New Latin by Galileo Galilei on March 13, 1610. It was the first published scientific work based on observations made through a telescope, and it contains the results of Galileo's early observations of the imperfect and mountainous Moon, the hundreds of stars that were unable to be seen in either the Milky Way or certain constellations with the naked eye, and the Medicean Stars that appeared to be circling Jupiter. -
Galileo Galilei: laws of falling body
A biography by Galileo's pupil Vincenzo Viviani stated that Galileo had dropped balls of the same material, but different masses, from the Leaning Tower of Pisa to demonstrate that their time of descent was independent of their mass. This was contrary to what Aristotle had taught: that heavy objects fall faster than lighter ones, in direct proportion to weight. -
Evangelista Torricelli invents the mercury barometer
Torricelli's chief invention was the mercury barometer. "This instrument is named from two Greek words, signifying two measures of weight, since by it a column of air is weighed against a column of mercury." The barometer arose from the need to solve a practical problem. Pump makers of the Grand Duke of Tuscany attempted to raise water to a height of 12 meters or more, but found that 10 meters was the limit with a suction pump. Torricelli employed mercury, thirteen times more dense than water. -
Robert Hooke: Discovers the Cell
Hooke coined the term cell for describing biological organisms, the term being suggested by the resemblance of plant cells to cells of a honeycomb. The hand-crafted, leather and gold-tooled microscope he used to make the observations for Micrographia, originally constructed by Christopher White in London, is on display at the National Museum of Health and Medicine in Washington, DC. -
Sir Isaac Newton: discovers that white light is a spectrum of a mixture of distinct coloured rays
In 1666, Newton observed that the spectrum of colours exiting a prism in the position of minimum deviation is oblong, even when the light ray entering the prism is circular, which is to say, the prism refracts different colours by different angles. This led him to conclude that colour is a property intrinsic to light—a point which had been debated in prior years. -
Ole Rømer: first measurement of the speed of light
Cassini had observed the moons of Jupiter between 1666 -1668, and discovered discrepancies in his measurements that, at first, he attributed to light having a finite speed. In 1672 Rømer went to Paris and continued observing the satellites of Jupiter as Cassini's assistant. Rømer added his own observations to Cassini's and observed that times between eclipses got shorter as Earth approached Jupiter, and longer as Earth moved farther away. Cassini made an announcement to the Academy of Sciences -
Benjamin Franklin: Lightning is electrical
Franklin started exploring the phenomenon of electricity in 1746 when he heard of the Leyden jar. Franklin proposed that "vitreous" and "resinous" electricity were not different types of "electrical fluid" (as electricity was called then), but the same "fluid" under different pressures. He was the first to label them as positive and negative respectively, and he was the first to discover the principle of conservation of charge. -
Mikhail Lomonosov: discovery of the atmosphere of Venus
Lomonosov was the first person to hypothesize the existence of an atmosphere on Venus based on his observation of the transit of Venus of 1761 in a small observatory near his house in Petersburg. In June 2012 a group of astronomers carried out experimental reconstruction of Lomonosov's discovery of Venusian atmosphere with antique refractors during the transit of Venus ( 5–6 June 2012). They concluded that Lomonosov's telescope was fully adequate to the task of detecting the arc of light. -
Hanaoka Seishū: develops general anaesthesia
Once perfected, Hanaoka began to administer his new sedative drink to induce a state of consciousness equivalent to or approximating that of modern general anesthesia to his patients. Hanaoka's success in performing this painless operation soon became widely known, and patients began to arrive from all parts of Japan. Hanaoka went on to perform many operations using tsūsensan, including resection of malignant tumors, extraction of bladder stones, and extremity amputations. -
William Herschel discovers infrared radiation.
Herschel was testing filters for the sun so he could observe sun spots. When using a red filter he found there was a lot of heat produced. Herschel discovered infrared radiation in sunlight by passing it through a prism and holding a thermometer just beyond the red end of the visible spectrum. This thermometer was meant to be a control to measure the ambient air temperature in the room.