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Mercury is the first planet from the Sun and the smallest in the Solar System. In English, it is named after the ancient Roman god Mercurius , god of commerce and communication, and the messenger of the gods. Mercury is classified as a terrestrial planet, with roughly the same surface gravity as Mars.
The timeline of discovery of Solar System planets and their natural satellites charts the progress of the discovery of new bodies over history. Each object is listed in chronological order of its discovery (multiple dates occur when the moments of imaging, observation, and publication differ), identified through its various designations (including temporary and permanent schemes), and the ...
The first extrasolar planet found to have a density compatible with being a rocky planet is CoRoT-7b in 2009. 55 Cancri e was found to be a terrestrial planet in 2011. First super-Earth orbiting a main sequence star [ NB 2 ]
The outer planets' orbits are chaotic over longer timescales, with a Lyapunov time in the range of 2–230 million years. [105] In all cases, this means that the position of a planet along its orbit ultimately becomes impossible to predict with any certainty (so, for example, the timing of winter and summer becomes uncertain).
This was the first evidence that anything other than the planets repeatedly orbited the Sun, [291] though Seneca had theorized this about comets in the 1st century. [292] Careful observations of the 1769 transit of Venus allowed astronomers to calculate the average Earth–Sun distance as 93,726,900 miles (150,838,800 km), only 0.8% greater ...
The first successful flyby of Mars was made by Mariner 4 in 1965. Mariner 10 first passed Mercury in 1974. The first probe to explore the outer planets was Pioneer 10, which flew by Jupiter in 1973. Pioneer 11 was the first to visit Saturn, in 1979.
French philosopher and mathematician René Descartes was the first to propose a model for the origin of the Solar System in his book The World, written from 1629 to 1633.. In his view, the universe was filled with vortices of swirling particles, and both the Sun and planets had condensed from a large vortex that had contracted, which he thought could explain the circular motion of the plane
Vostok 1 – First crewed Earth orbiter Mariner 2 – First successful Venus flyby Mariner 4 – First successful Mars flyby Luna 9 – First successful lunar lander Zond 5 – First lunar flyby and return to Earth, first terrestrials to circle the Moon Apollo 8 – First crewed lunar orbiter Apollo 11 – First crewed lunar landing