The XIX century was a time of rapid development of astronomical science and celestial mechanics. The number of observatories in Europe was increasing. The first observatories in the Southern Hemisphere were opened by D. Herschel and N. Lacaille. The size of the telescopes also grew, so in 1845 the Leviathan 2-meter reflector built by W. Parsons came into operation (in the XIX century this achievement was never surpassed by anyone); in 1861 V. Lasalle built a 122-cm reflector.
In 1836, photometric observation of stars began, pioneered by J. Herschel, in 1840 the first results of observations of the Sun in the infrared range were obtained, in 1841-45 by the efforts of W. Bond and J. Bond (USA) photographic astronomy was born, in 1874 the first photographic atlas of the Moon was published.
In 1859-62, R. Bunsen and G. Kirchhoff developed the basics of spectral analysis, which made a real revolution in observational astronomy, since through this method it was possible to obtain information about the chemical composition of celestial bodies that was not available at that time in any other way. With the help of spectral analysis, for the first time it was possible to scientifically prove the similarity of the chemical composition of the Sun and planets, and thus obtain a sufficiently convincing argument in favor of the material unity of the Universe.
At the beginning of the XIX century, it became clear that meteoritic matter has a cosmic origin, and not atmospheric or volcanic, as previously thought. Regular meteor showers have been recorded and classified. In 1834, Berzelius discovered the first unearthly mineral in a meteorite — troilite (FeS). By the end of the 1830s, meteor astronomy had formed as an independent field of space science.
The attention of scientists is attracted by the tasks of searching for unknown planets of the Solar system. In 1796, a detachment of the "heavenly police" was created to detect a planet located, according to the Titius-Bode law, between Jupiter and Mars. The hypothetical planet has already been given a name — Phaeton, but an asteroid belt has been discovered instead. So, on January 1, 1801, the Italian J. Piazzi discovered Ceres — it was noticed by chance, ranked among comets and immediately lost; Fortunately, the young Karl Gauss just at that time developed a method for determining the orbit from three observations, and in 1802 Heinrich Olbers first found Ceres, and then discovered two more minor planets between Mars and Jupiter, Pallas in 1802 and Vesta in 1807. The fourth asteroid, Juno, was discovered by Carl Harding (Germany) in 1804. Olbers put forward the first hypothesis about the causes of the formation of the asteroid belt. Until the end of the century, up to 400 were discovered. The term "asteroids" was proposed by Herschel.
1802 — V. Wollaston (England) invents a slit spectroscope. 7 dark lines were detected in the spectrum of the Sun.
1811 — Dominique Arago invents a polarimeter and with its help proves that the solar photosphere is a hot gas. The body of the Sun, however, was still considered by many scientists to be solid and even cold.
1814-1815 — Joseph Fraunhofer discovers 576 dark lines in the spectrum of the Sun. The laboratory sodium line coincided with the dark solar one. Spectral analysis soon appears.
1834 — German astronomer Friedrich Wilhelm Bessel proves the absence of an atmosphere on the moon (there is no refraction at the edge of the lunar disk).
1837 — Vasily Struve, the founder of the Pulkovo Observatory, discovered a one—year parallax at the star (0.12" at Vega); in 1838, Bessel discovered and very accurately measured the parallax at 61 Cygni, and T. Henderson - at Alpha Centauri. Until the end of the XIX century, about fifty stellar parallaxes were measured.
1839-1840 — photography begins to be used in astronomy (Louis Daguerre and Dominique Arago received pictures of the Moon).
1842 — the first photographs of the Sun were obtained.
1843 — G. Schwabe was the first to discover the periodicity in the change in the number of sunspots and estimated the period at about 10 years. In 1852, this pattern was rediscovered by R. Wolf, who gave a more accurate estimate (11 years) and found that the increase in the number of spots causes geomagnetic disturbances. The connection of sunspots with terrestrial processes, noticed by Herschel, is beginning to become clearer.
1845 — the giant reflector of the Irish astronomer William Parsons, Earl of Ross, came into operation. Herschel's mistake was immediately discovered — most of the "planetary" nebulae turned out to be star clusters. In the same year, an outstanding discovery was made — the spiral structure of the M 51 nebula, and soon a dozen other nebulae.
1846 — the triumph of Newtonian mechanics was the discovery of Neptune, the eighth planet of the Solar System, discovered "at the tip of a pen." The honor of the discovery was shared by Cambridge mathematician John Adams, French astronomer Urbain Leverrier and observer — Berlin astronomer Johann Halle. The planet was discovered only 52' from the place indicated by the calculations. Almost immediately, William Lascelles discovers Neptune's satellite, Triton.
1850 — the first photo of the Vega star.
1851-1852 — laboratory measurement of the speed of light; idea by Dominique Arago, execution by Jean Foucault and Armand Fizeau. Foucault demonstrates an experiment with a pendulum proving the rotation of the Earth around an axis (Foucault's pendulum).
1857 — the exact scale of stellar magnitudes (Norman Pogson). Since 1876, the production of photometric catalogs at the new school has begun.
1858 — the first photograph of a comet.
1859 — J. K. Maxwell proved the meteoritic structure of Saturn's ring. Urbain Leverrier discovers the inexplicable secular displacement of the perihelion of Mercury. R. H. Carrington for the first time describes a solar flare.
1859-1862 — Kirchhoff and Bunsen developed a powerful method for remote investigation of the chemical composition of extraterrestrial objects — spectral analysis. Already in 1861, Kirchhoff published a preliminary chemical composition of the solar atmosphere.
1862 — A. G. Clark discovered a satellite star of Sirius (Sirius-B), predicted by Bessel.
1867 — shifted spectra of stars in combination with the Doppler principle were used by Huggins to determine the radial velocities of celestial bodies.
1868 — N. Lockyer discovered a line in the spectrum of the Sun that did not correspond to any of the chemical elements known at that time, and named this new element helium. Later, helium was found on Earth. Lockyer discovered a change in the spectrum of sunspots during the 11-year cycle of solar activity, and in 1873 he guessed that the decay of chemical elements occurs in the depths of the Sun.
1870 — the beginning of theoretical astrophysics: Jonathan Homer Lane derived a differential equation describing the structure of a star under the assumption that the star is a gas ball in a state of hydrostatic equilibrium (the Lane-Emden equation).
1877 — Assaf Hall discovers the moons of Mars Phobos and Deimos, and Giovanni Schiaparelli — the Martian "channels".
1879 — J. H. Darwin publishes the hypothesis of the tidal origin of the Moon (its separation from the Earth). S. Fleming proposes to divide the Earth into time zones. In 1884, the time zone was introduced in 26 countries; at the same time, an international agreement was adopted on the choice of the Greenwich meridian as zero and the passage of the date change line.
1885 — the first observation of a nova flare in the Andromeda Nebula (S Andromeda); later it turned out that it was a supernova.
1898 — W. G. Pickering discovers Phoebe, a satellite of Saturn, and its amazing feature is the reverse rotation in relation to its planet.