Satellites like Kepler worked overtime to discover hundreds of new planets in our galaxy. But how did we first discover the planets in our local volume of space? That is, in our bubble called the Solar System. Here are all the stories of how astronomers living hundreds of years ago discovered every planet in our solar system.
Mercury
Being the closest planet to the Sun in our solar system, Mercury rotates within 46-70 million kilometers from the star. Ancient astronomers knew about the speed of the planet's rotation around the sun: Assyrian astronomers associated the planet with gods such as Naboo, the scribe and messenger of the gods; the ancient Greeks called this body Mercury, also in honor of the messenger of the gods. What is the reason for this association? A year on this planet lasts only 88 days, the shortest of all.
In 1631, astronomer Pierre Gassendi first observed the transit of Mercury through the sun, and just a couple of years later, another astronomer Giovanni Zupi discovered phases indicating that the planet revolves around the sun. Other astronomers gradually added their own to these discoveries: the Italian astronomer Giovanni Schiaparelli observed the planet and concluded that Mercury was tidal blocked by the sun, that is, it was always facing the luminary with only one side.
In the modern era of space exploration, other discoveries have also come: a lot has been learned about the planet quite recently. Soviet scientists first used radar to explore the planet in the early 1960s, and scientists at the Arecibo Observatory, using a radio telescope, discovered that the planet rotates once every 59 days, not 88, as previously thought. In 1974, the Mariner 10 probe visited the planet for the first time, made several overflights, mapping the surface, and in 2008 the MESSENGER probe arrived to the planet, in whose orbit it remains to this day.
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Venus
The second planet in the solar system, Venus is the brightest of the planets observed from Earth. For this reason, it has been studied since time immemorial: the first records about it appeared even among the Babylonians, who named the planet Ishtar. The Romans saw Venus as the goddess of beauty, and the Maya believed that the planet is the brother of the sun. In 1610, Galileo Galilei observed the phases of Venus, confirming that the planet was indeed orbiting the sun. Due to the planet's dense atmosphere, surface observations were not possible until the 1960s, but many believed that Venus had life because the planet was similar in size to Earth.
In 1958, radar surveys revealed that the planet's surface was unbearably hot - and therefore inhospitable to life. Humanity has decided to take a closer look at the evil sister of the Earth. The first attempt, the Soviet probe Venera 1, was made in 1961 and was unsuccessful, but Mariner 2, launched by the United States, succeeded, circling the planet and confirming its temperature and the absence of a magnetic field. The new Soviet mission, Venera 4, successfully reached Venus and sent back information about the planet's atmosphere before being burnt to the ground during its reentry. These missions were followed by several others: Mariner 5, Venus 5 and 6, Venera 7 with a successful landing, and then a repeat of success by the Venera 8 forces. These last two probes were the first man-made objects to successfully land on the surface of another planet. Both were destroyed by the pressure and heat of the planet, but the Soviet Union continued to send probes. NASA too: Pioneer 12 orbited the planet for 14 years, mapping the surface, and Pioneer 13 sent several probes straight to it.
Earth
The earth has been continuously observed by humanity from the very moment of its inception. But although we knew we were on solid ground, we had to wait a bit to find out the true nature of our home. For many centuries, people believed that the Earth was not the same object as those observed above it: everything revolved around the Earth. Already in the time of Aristotle, philosophers determined that the Earth has a spherical shape, observing the shadow of the Moon.
Mikolaj Copernicus - also known as Nicholas - postulated a heliocentric view of the solar system as early as 1514. The book "On the Rotation of the Celestial Spheres" was first published in 1543 and challenged the conventional wisdom. The theory was controversial, but it was followed by three voluminous works by Johannes Kepler on Copernican astronomy. Kepler developed three laws of planetary motion: "The planets move around the Sun in an ellipse, with the Sun in one of the focuses", "Each planet moves in a plane passing through the center of the Sun, and at equal time intervals the radius vector connecting the Sun and the planet describes equal areas "," The squares of the periods of revolution of the planets around the Sun are referred to as cubes of the semi-major axes of the planets' orbits. "These laws helped determine the motion of the planets and allowed us to question the previous form of the solar system. At first, Kepler's theories were not popular, but eventually they spread throughout Europe. By the time Copernicus published his views, Fernand Magellan's expedition was able to circumnavigate the globe in 1519.
It wasn't until October 24, 1946 that we got a glimpse of our homeworld when the first picture of Earth was taken with a modified V-2 rocket launched from a New Mexico test site.
Mars
The blood-red fourth planet in our solar system has long been associated with the Roman god of war called Mars. And if many believed that Venus could well have an earthly atmosphere, there were similar thoughts on the topic of Mars. In 1877, while exploring the planet with a telescope, astronomer Giovanni Schiaparelli described a series of features that he called Canali. This word was translated incorrectly, and channels suddenly appeared on Mars, and, as people thought, of artificial origin. Twenty years later, another astronomer, Camille Flammarion, also determined the features of the artificial surface, and people finally believed that there could be life on the planet. Public perception has led to a number of Mars science fiction novels such as HG Wells' War of the Worlds.
The advances in telescopes that came later made it possible to look at the planet in a new way. Astronomers were able to measure the temperature of the planet, determine its atmospheric content and mass. Throughout the 1960s, the Soviet Union tried to send eight probes to Mars, but never succeeded, although orbiters successfully arrived on Mars in the 1970s. NASA unsuccessfully tried to send Mariner 3 to Mars, but Mariner 4, launched in 1964, successfully circled the planet and showed that it was dead. And yet, following these scouts, the Viking missions became the real first invasion: on July 20, 1976, the probe landed on the Red Planet for an unprecedented mission that lasted until 1982. It was soon followed by Viking 2, which landed on Mars in September 1976 and operated until 1980.
Despite the success of the mission, it was not until 1997 that the first mobile rover was landed on Mars as part of the Mars Pathfinder mission. The ensuing Mars Climate Orbiter mission failed due to human error, and several more Mars probes simply did not make it. In 2004, NASA launched the Spirit and Opportunity rovers, which proved to be far less successful. In 2012, these rovers were replaced by Curiosity, which is still in operation.
Jupiter
The largest planet in our solar system, Jupiter, has been observed since ancient times. She helped the Chinese lead a 12-year cycle and was named after the king of the Roman gods. She has also been the target of many astronomers. Galileo was the first to observe Jupiter's four major moons, now known as the Galilean moons: Io, Europa, Ganymede, and Callisto, named after Zeus's lovers. Astronomer Robert Hooke discovered a large system of storms on the gas giant, and in 1665 this was confirmed by Giovanni Cassini, in parallel for the first time noticing the Great Red Spot, which was formally discovered in 1831. Lacking solid ground, storms on Jupiter rage as fast as they can. Astronomers Giovanni Borelli and Cassini, using orbital tables and mathematics, discovered something strange: being in opposition to Earth, Jupiter is seventeen minutes late relative to the calculations,which suggests that light is not an instantaneous phenomenon, but has a delay.
In the 1900s, observations led to other discoveries: using a radio telescope to study the Crab Nebula from 1954 to 1955, astronomer Bernard Burke discovered interference from one part of the sky and eventually figured out that Jupiter was emitting waves along with the planet's radiation. In 1973, the Pioneer missions became the first probes to fly past the planet and take a series of close-up images. In 1977, two probe missions, Voyager 1 and Voyager 2, were launched from Earth to study the outer planets of the solar system. The first of them reached Jupiter two years later: Voyager 1 arrived in March 1979 and Voyager 2 arrived in July 1979. Both discovered a lot of useful information about the planet and its satellites, before heading out further, found a small ring system and additional satellites. In 1992, the Ulysses mission arrived at Jupiter;in 1995, the Galileo probes entered the planet's orbit; Cassini flew in 2000 and New Horizons in 2007. In 1994, scientists also observed something incredible: the planet Shoemaker-Levy crashed into the southern horizon of Jupiter, leaving a huge scar in the planet's atmosphere. Attempts are under way to study Jupiter's moons, some of which may be excellent candidates for life.
Saturn
The sixth planet from the Sun is perhaps the most interesting and is the last classically recognized planet: the Romans named it after their god of agriculture. And only in 1610, Galileo drew attention to the most striking feature of the planet. While studying its properties, he decided that he had stumbled upon several orbiting satellites. But in 1655, Christian Huygens, armed with a more powerful telescope, found out that this feature is the rings surrounding the planet. Shortly thereafter, he found Saturn's first moon, Titan. In 1671, Giovanni Cassini found four additional moons: Iapetus, Rhea, Tethys and Dione in the gaps between the planet's rings, after which it dawned on him: these rings consisted of smaller particles. In 1789, German astronomer William Herschel noted two more moons: Mimas and Enceladus, and over the next hundred years, two more satellites were found:Hyperion in 1848 and Phoebus in 1899.
When NASA began exploring the outer planets, Saturn first visited the Pioneer 11 probe in September 1979, taking several images. The Voyager twin probes arrived next, in 1980 and 1981, providing us with high-resolution imagery. The planet became a fork for a pair of probes: Voyager 1 used Saturn to accelerate and take off from the solar system, while Voyager 2 went to Uranus. Only in 2004 did the planet receive its next visitor in the form of the Cassini mission, which is still studying the planet and its satellites.
Uranus
The seventh planet, Uranus, was difficult to find without the help of telescopes, so its history is not as long as that of other planets. Observing the skies in December 1690, astronomer John Flamsteed first discovered the planet, but decided it was the star 34 Tauri. It was only on March 31, 1781 that Herschel was the first to decide that this star is actually a comet. Further study of this "comet" led to the fact that it turned out to be a planet. Herschel named it Georgium Sidus after King George III, but eventually the planet was named Uranus after Chronos. The discovery was unprecedented: the most distant object in the solar system was found. In the 19th century, astronomers noticed something strange about the orbit of this object: it did not correspond to mathematical theories and deviated from its course. Apparently he was being influenced by something else, further down the solar system.
But the most unusual feature of the planet was its orientation: instead of rotating like other planets in the system, Uranus lies and rotates on its side. The reason for this is unknown; planetary collision is put forward as a theory. In 2009, members of the Paris Observatory suggested that when the planet was in its embryonic state, a moon formed in the planetary disk, which rocked the planet. In 1986, the Voyager 2 probe passed Uranus, studying the planet's atmosphere and discovering a number of additional satellites and a ring system. He became the first and only probe to reach this planet; no further missions are currently planned.
Neptune
The last "official" planet in our solar system is Neptune. Rotating at 30 AU. That is, from the Sun, it became the first planet to be discovered using mathematical calculations rather than direct observation. While studying Uranus, astronomers found that the planet did not match their predictions and tried to resolve this issue. At that time, it was already known that the planet's orbit is influenced by other large bodies of the solar system, but even with all this, Uranus violated expectations. In 1835, Halley's comet reached perihelion a little later than expected, which led astronomers to the idea that there was an additional object in the system that affects Uranus.
Astronomers began to look further to explain the planet's motion. England and France had their own astronomers who first stumbled upon the trail: John Coach Adams and Urburn Le Verrier. From 1843 to 1845, Adams did the correct calculations, but was rejected by the Royal Astronomical Society. Le Verrier came to a similar decision and turned to Johann Gottfried Halle, who, following Le Verrier's instructions, discovered a new planet where predicted, on September 23, 1846. The following month, an English astronomer discovered Neptune's moon Triton. The solar system has doubled in size with the discovery.
Neptune was visited by the Voyager 2 probe on August 25, 1989, where it took readings from the planet and went to study Triton, next to which he also found the moon Nereid. At the same time, the planet was found to be very warm, much warmer than expected, and has a turbulent atmosphere with a Great Dark Spot similar to Jupiter's Great Red Spot. After visiting Neptune, Voyager 2 left the solar system and went into deep space.
The history of the discovery of the solar system, its planets, is an interesting way to look at the history of science and human understanding of our close neighbors. The study of our planets has changed our view of the world around us and our understanding of our place in the universe.
ILYA KHEL