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The Big Bang Theory is the leading explanation about how the universe began. At its simplest, it talks about the universe as we know it starting with a small singularity, then inflating over the next 13.8 billion years to the cosmos that we know today.
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Giuseppe Piazzi discovers Ceres. Piazzi discovered Ceres, the first known asteroid, on January 1, 1801, the first day of the 19th century.
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William Wolleston sees dark lines in solar spectrum. Wollaston passed sunlight through a prism and noticed that there were numerous dark bands and lines in the spectrum.
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Meteorite shower at l'Aigle convinces scientists that meteorites have an extraterrestrial origin. A careful investigation of the shower by Edouard Biot convinced most skeptics that meteorites really do fall from the sky.
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Gaspar de Coriolis discovers Coriolis effect. The Coriolis effect, the apparent deflection of moving bodies due to Earth's rotation, explained many atmospheric circulation patterns
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h Carinae brightens to become second brightest star. h Carinae is normally too faint to be seen, but between 1837 and 1860 it was the brightest star in the sky.
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Friedrich Bessel, Wilhelm Struve, Thomas Henderson measure the distances of stars. Bessel, Struve, and Henderson, working independently, almost simultaneously measured the parallaxes, and hence the distances, of nearby stars. These were the first measurements, rather than estimates, of stellar distances.
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Christian Johann Doppler describes the Doppler effect. Doppler discovered that the wavelength and frequency of a wave change if the source of the wave moves toward or away from the observer
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Calculations of Adams and Leverrier lead to discovery of Neptune. Adams and Leverrier independently calculated the location of the unknown planet, Neptune, that was required to explain discrepancies in the orbit of Uranus.
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Jean Foucault uses pendulum to demonstrate Earth rotates. Foucault showed that the pendulum swung in the same plane but the Earth rotated under it, causing an apparent change in the direction of the pendulum's swing.
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James Clerk Maxwell discovers velocity distribution function for a gas. Maxwell showed that the distribution of velocities of the atoms or molecules in a gas depends on temperature and the mass of the molecules.
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William Huggins identifies chemical elements in stars. Huggins studied the spectra of bright stars and found that the dark lines in their spectra matched the wavelengths of atoms measured in terrestrial laboratories.
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Asaph Hall discovers Phobos and Deimos. Remarkably, the prediction that Mars had two small satellites was made by Jonathan Swift 151 years before Hall's discovery.
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Lord Kelvin and Hermann von Helmholtz estimate the age of the Sun. Kelvin and Helmholtz independently calculated the length of time it would have taken for the Sun to have shrunk to its present size. This time, called the Kelvin-Helmholtz time, is about 20 million years.
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Giovanni Schiaparelli discovers "canals" of Mars. Schiaparelli reported thin, dark lines crisscrossing the surface of Mars. The discovery raised the possibility of intelligent life on Mars
