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Planetary habitability in the Solar System is the study that searches the possible existence of past or present extraterrestrial life in those celestial bodies. As exoplanets are too far away and can only be studied by indirect means, the celestial bodies in the Solar System allow for a much more detailed study: direct telescope observation, space probes, rovers and even human spaceflight.
This is a list of active space probes which have escaped Earth orbit. It includes lunar space probes, but does not include space probes orbiting at the Sun–Earth Lagrangian points (for these, see List of objects at Lagrangian points). A craft is deemed "active" if it is still able to transmit usable data to Earth (whether or not it can ...
Any planet in orbit around a red dwarf would have to huddle very close to its parent star to attain Earth-like surface temperatures; from 0.3 AU (just inside the orbit of Mercury) for a star like Lacaille 8760, to as little as 0.032 AU for a star like Proxima Centauri [89] (such a world would have a year lasting just 6.3 days). At those ...
Theia or Orpheus, [21] a Mars-sized impactor believed to have collided with the Earth roughly 4.5 billion years ago; an event which created the Moon. Evidence from 2019 suggests that it may have originated in the outer Solar System. [22] Vulcan, a hypothetical planet once believed to exist inside the orbit of Mercury. Initially proposed as the ...
Kepler-452b (sometimes quoted to be an Earth 2.0 or Earth's Cousin [4] [5] based on its characteristics; also known by its Kepler object of interest designation KOI-7016.01) is a candidate [6] [7] super-Earth exoplanet orbiting within the inner edge of the habitable zone of the sun-like star Kepler-452 and is the only planet in the system discovered by the Kepler space telescope.
If Earth is not ejected during a stellar encounter, then its orbit will decay via gravitational radiation until it collides with the Sun in 10 20 (100 quintillion) years. [110] If proton decay can occur and Earth is ejected to intergalactic space, then it will last around 10 38 (100 undecillion) years before evaporating into radiation. [111]
Another common form of resonance in the Solar System is spin–orbit resonance, where the rotation period (the time it takes the planet or moon to rotate once about its axis) has a simple numerical relationship with its orbital period. An example is the Moon, which is in a 1:1 spin–orbit resonance that keeps its far side away from
(110–210 Earth radii) 6.36×10 6 –1.27×10 7: The space dominated by Earth's magnetic field and its magnetotail, shaped by the solar wind. [17] Earth's orbit: 299.2 million km [b] 2 AU [c] 2.99×10 8: The average diameter of the orbit of the Earth relative to the Sun. Encompasses the Sun, Mercury and Venus. [18] Inner Solar System ~6.54 AU ...