Let’s start with the Greeks
About the closest “neighbors” of the Earth – Mercury, Venus, Mars, Jupiter and Saturn – people knew long ago. According to the Ptolemaic system, in the center of the solar system the Earth was located, and it revolved around Mars, Jupiter, Saturn and the Moon and the Sun, which are then considered planets. About the fact as to whether Mercury and Venus, the planets, the ancient Greeks consensus was not.
According to the heliocentric system described by Nicholas Copernicus,
planet already have in place: at the center of it was the sun, and around it revolved Mercury, Venus, Earth, Mars, Jupiter, Saturn.
All of these planets can be seen with the naked eye – in the end XVIII century telescope has helped people to expand the boundaries of the solar system.
Comet was the planet
The earliest documented evidence of observations of Uranus should be considered records of the English astronomer John Flamsteed, who observed Uranus in 1690, at least six times. Flamsteed registered it as number 34 star in the constellation Taurus. The French astronomer Pierre Charles Le Monier observed Uranus, too, from 1750 to 1769 years.
However, the honor of the opening of a new planet belongs to William Herschel – musician and amateur astronomers from England. Disappointed acquired in 1773 a small reflecting telescope with a focal length of 2.5 feet, Herschel has made his own reflecting telescope length of almost 2 meters and the diameter of the primary mirror of 20 cm and with the help of his new instrument began in 1775 a review of the sky.
By the way, Herschel continually building more and more new reflecting telescope. King patronized him and gave the money to build a huge reflector, which was built in 1789 and
became the largest telescope of its time, with a mirror diameter of 120 cm with a tube length of 12 m.
March 13, 1781, William Herschel was engaged in observations of the parallax of stars in the constellation Taurus. He noticed Dimstar and suggested that it might be a comet. Herschel continued observation of the mysterious star, and found that it moves too slowly for a comet. Two months later, Petersburg academician Andrei Leksel calculated the orbital parameters of this celestial body, has shown that it revolves around the sun in an orbit whose radius is 18 times the radius of Earth’s orbit. The resulting orbit is more like a planet than a comet. It became clear that
the first time since antiquity in the solar system was discovered a new planet.
the newly discovered celestial body Herschel suggested naming ” George planet “in honor of the law at the time in England, King George III. However, the name did not stick, and it became common other name – Uranium proposed in the year of the opening of the planet by German astronomer Johann Bode. Curiously, Uranus – the only planet whose name is not taken from Roman and Greek mythology.
Planet at the tip of the pen
After the discovery of Uranus in 1781, astronomers began to notice the anomalies in his behavior: the motion of the planets did not fit with the theoretical calculations of scientists. That is why the Russian astronomer Andrei Ivanovich Leksel suspected that
Uranus influences the attraction of another cosmic body, which is farther from the sun,
– expressed this assumption was at the end of the XVIII century.
Later , a few decades later, we returned to the subject, and other astronomers – Thomas Hussey, Louis Vartman and others. In the middle of the XIX century, re-analysis of the trajectory of motion of Uranus independently do the British astronomer John Adams and Urbain Le Verrier Frenchman. Due to this, scientists were able to see where there may be not yet discovered the planet. Making theoretical calculations Le Verrier asked for help from Johann Galle of the Berlin Observatory assistant, asking “take some time observed in that part of the sky where there may be an unknown planet.” Halle volunteered to help young astronomer Heinrich d’Arrest.
September 24, 1846 at 00 hours 00 minutes 14 seconds, astronomers recorded the object about eight magnitude, which was not on the star the sky.
Observations on the subject lasted until his call – half of the third hour of the night. Observations continued the next night with a more powerful telescope. As a result, astronomers doubt remained: a new planet, dubbed Neptune, was found. Despite the fact that the calculations of Adams and Leverrier were similar, it is considered the discoverer of the planet Le Verrier – according to the director who became cruise Paris Observatory Francois Arago (who suggested Verrier to seek a planet), astronomer, discovered Neptune “on the tip of a pen.” In 1846 the Royal Society of British astronomer awarded the highest award – the Copley Medal. Adams thus was not mentioned.
It opened a new world
The first faint images of Pluto were obtained in 1915 (March 19 and April 17). They were made at the Observatory of Percival Lowell, who founded the project to find the ninth planet – “Planet X”. However, then, in 1915, Pluto has not been identified as a planet.
In 1919, Pluto is “lit up” and the images captured in the Mount Wilson Observatory. But the pictures were not very good quality, and Pluto lost among the other stars. Even later, when his whereabouts have been known to find an object in these images managed with difficulty.
In 1929, the director of the Lowell Observatory commissioned photographer Clyde Tombaugh technician, who at that time was 23 years old, to continue the search for “Planet X”. Tombaugh engaged in methodical astrophotography: Each section was photographed several times at intervals of a few days, and then compared the photos. The aim of the scientist was to find an object that would change its position. After nearly a year of work of Clyde Tombaugh managed to find nine planets:
February 18, 1930 the astronomer gave a moving object in the images of 23 and 29 January. After the discovery was confirmed by new images, the discovery of the ninth planet was reported in the Harvard College Observatory – it happened March 13, 1930.
The discovery of a new planet Tombaugh naprorochili in his youth. Born into a family of a poor farmer boy became interested in astronomy at age 12, when I first looked through a telescope. After high school classmates Tombaugh wrote in the yearbook phrase: “It will open a new world.” Tombaugh’s parents had no money for it, to pay for his studies, so he began to study astronomy alone: he made the telescope, based on observations made with it, I made drawings of Jupiter craters. Thanks to these figures, which he sent to the Lowell Observatory, he was accepted there as a photographer laboratory. Go to university Tombaugh could only once discovered Pluto.
However, the ninth planet, Pluto was a few decades: in 2006, the International Astronomical Union adopted a formal definition of the word “planet” and demoted Pluto to the rank of “dwarf planet “. The debate about this decision being still – detail science department “Gazety.Ru» of them have told .
First Among Equals
The first exoplanet was discovered in 1995 the star 51 Pegasi in the constellation astronomers Michel Mayor and Didier Kelosom in the Haute-Provence Observatory in France. The work of scientists, published in the journal Nature ,
opened a new direction in astronomy today exoplanet discovery put on stream.
With the help of an optical spectrometer ELODIE, measuring the Doppler shift of lines Kelos Mayor and in 1994 started regular measurement of radial velocities in 142 sunlike stars relatively close to the sun. Pretty soon it was discovered 51 Pegasi star fluctuations occurring with a period of 4.23 days, caused by the influence of a star orbiting the planet it. October 6, 1995 announced the discovery of extrasolar planets called 51 Pegasi b.
Open scientists exoplanet is located 50 light-years from Earth. It belongs to the class of “hot Jupiter” – a gas giant with a mass of at least half the mass of Jupiter. At this she is closer to its star than Mercury is to the Sun, and orbits at a speed of 136 km / s. Scientists estimate that the planet’s atmosphere is heated to temperatures above 1000 ° C.
Initially, the scientific community doubt the veracity of the discovery. It was expected that other star systems will be similar to our own, and 51 Pegasi b was characteristic sound weird.
Fortunately, less than a week the discovery was confirmed by American astronomers Geoffrey Marcy and Paul Butler of San Francisco a group of researchers. In parallel with the French researchers are also involved in the search for extrasolar planets by the radial velocities and had a chance to go down in history as people discovered the first exoplanet from the ordinary star.
However, a group of American researchers based on the idea that a massive gas giants should be at a great distance from the star, and therefore I assumed that this would require long-term systematic observations. As a result, American scientists
calibrated equipment to find the smallest fluctuations in the spectrum – while in practice it turned out to be exactly the opposite.
Opening by Michel Mayor and Didier Kelosa was the first step, a new era in astronomy. After him, it was opened many extrasolar planets, most of which are gas giants. To date, confirmed the existence of more than two thousand extrasolar planets. A great contribution to the search for them has made Space Telescope “Kepler” has discovered more than a thousand extrasolar planets. Currently, of particular interest is the search for Earth-like extrasolar planets and possible signs of life on them.
Life is not
September 30, 2010 the astronomical community blew up news of the discovery of the first potentially habitable exoplanet. Scientists from the University of California at Santa Cruz and the Carnegie Institution in Washington, said that habitable planet could be Gliese 581g – the sixth planet in the red dwarf star Gliese 581.
The researchers made evaluation of a number of parameters of this planet, and concluded that there
may be an atmosphere of water and exist in liquid form.
For example, scientists have found that this planet has a radius of 1.2 to 1.5 Earth radius, mass, from 3.1 to 4.3 Earth masses and a period of revolution around its star in 36.6 Earth days. Semi-major axis of the elliptical orbit of the planet is about 0.146 astronomical units (1 astronomical unit – the average distance between Earth and the Sun, which is approximately 146.9 million kilometers). Acceleration of gravity on the surface of the planet exceeds this parameter for the Earth is 1.1 – 1.7 times.
As for the temperature on the surface of Gliese 581g, it is, according to scientists, ranging from -31 to -12 ° C.
However, a sensational statement astronomers confirmed that a year later scientists said , that in the Gliese 581 system, there are only four of the planet (Gliese 581g was considered the sixth), and potentially habitable is not among them.
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