"at the present time."" In 1821, the ""Caledonian Mercury"" wrote of the British Empire, ""On her dominions the sun never sets; before his evening rays leave the spires of Quebec, his morning beams have shone three hours on Port Jackson, and while sinking from the waters of Lake Superior, his eye opens upon the Mouth of the Ganges."" Daniel Webster famously expressed a similar idea in 1834: ""A power which has dotted over the surface of the whole globe with her possessions and military posts, whose morning drumbeat, following the sun and keeping company with the hours, circles the earth"
"Proxima Centauri b Proxima Centauri b (also called Proxima b or Alpha Centauri Cb) is an exoplanet orbiting in the habitable zone of the red dwarf star Proxima Centauri, which is the closest star to the Sun and part of a triple star system. It is located about 4.2 light-years (1.3 parsecs, 40 trillion km, or 25 trillion miles) from Earth in the constellation of Centaurus, making it the closest known exoplanet to the Solar System. Proxima Centauri b orbits the star at a distance of roughly with an orbital period of approximately 11.2 Earth days, and has an estimated"
"that between Saturn and the Sun (11.2 AU). Alpha Centauri C, or Proxima Centauri, is a small and faint red dwarf (Class M). Though not visible to the naked eye, Proxima Centauri is the closest star to the Sun at a distance of , being slightly closer than Alpha Centauri AB at a distance of . Currently, the distance between Proxima Centauri and Alpha Centauri AB is about , equivalent to about 430 times the radius of Neptune's orbit. Proxima Centauri b is an Earth-sized exoplanet in the habitable zone of Proxima Centauri; it was discovered in 2016. ""α Centauri"""
"Sun's mass and that is orbited by a white dwarf, Sirius B. The nearest brown dwarfs are the binary Luhman 16 system at 6.6 light-years. Other systems within ten light-years are the binary red-dwarf system Luyten 726-8 (8.7 ly) and the solitary red dwarf Ross 154 (9.7 ly). The closest solitary Sun-like star to the Solar System is Tau Ceti at 11.9 light-years. It has roughly 80% of the Sun's mass but only 60% of its luminosity. The closest known free-floating planetary-mass object to the Sun is WISE 0855−0714, an object with a mass less than 10 Jupiter masses roughly"
"of the distance from the Earth to the Sun. Comparatively, Mercury, the closest planet to the Sun, has a semi-major axis distance of 0.39 AU. Proxima Centauri b receives about 65% of the amount of radiative flux from its host star that the Earth receives from the Sun - for comparison Mars receives about 43%. Most of the radiative flux from Proxima Centauri is in the infrared spectrum. In the visible spectrum the exoplanet receives only ~3% of the PAR (400-700 nm) of Earth irradiance - for comparison Jupiter receives 3.7% and Saturn 1.1%. So it would usually not get"
"in the WGSN's second bulletin issued in October 2016. The next additions were done on 1 February, 30 June, 5 September and 19 November 2017, and on 6 June 2018. All are included on the current List of IAU-approved Star Names, last updated on 1 June 2018. The star nearest to Earth is typically referred to simply as ""the Sun"" or its equivalent in the language being used (for instance, if two astronomers were speaking French, they would call it ""le Soleil""). However, it is sometimes called by its Latin name, Sol, in science fiction. With the advent of the"
"about 4.4 light-years away. Alpha Centauri A and B are a closely tied pair of Sun-like stars, whereas the small red dwarf, Proxima Centauri, orbits the pair at a distance of 0.2 light-year. In 2016, a potentially habitable exoplanet was confirmed to be orbiting Proxima Centauri, called Proxima Centauri b, the closest confirmed exoplanet to the Sun. The stars next closest to the Sun are the red dwarfs Barnard's Star (at 5.9 ly), Wolf 359 (7.8 ly), and Lalande 21185 (8.3 ly). The largest nearby star is Sirius, a bright main-sequence star roughly 8.6 light-years away and roughly twice the"
"may be orbiting Sun-like stars. The nearest such planet may be 12 light-years away. Scientific findings since the 1990s have greatly influenced the scope of the fields of astrobiology, models of planetary habitability and the search for extraterrestrial intelligence (SETI). NASA and the SETI Institute have proposed categorising the increasing number of planets found using a measure called the Earth Similarity Index (ESI) based on mass, radius and temperature. According to this measure, as of 23 July 2015, the confirmed planet currently thought to be most similar to Earth on mass, radius and temperature is Kepler-438b. Scientists estimate that there"
"Venus for the seventh and last time, decreasing its period to 88 or 89 days and allowing it to approach closer to the Sun. The perihelion distances above are from the center of the Sun. For altitude above the surface, subtract one solar radius ≈ 0.7 Gm.<br> By way of comparison, the planet Mercury orbits the Sun at a distance varying from about 46.0 Gm (46,001,200 km) at its closest to about 69.8 Gm (69,816,900 km) at its farthest. Parker Solar Probe Parker Solar Probe (previously Solar Probe, Solar Probe Plus, or Solar Probe+, abbreviated PSP) is a NASA robotic"
"are gravitationally bound to the star. Almost all of the planets detected so far are within the Milky Way. Nonetheless, evidence suggests that extragalactic planets, exoplanets further away in galaxies beyond the local Milky Way galaxy, may exist. The nearest exoplanet is Proxima Centauri b, located 4.2 light-years (1.3 parsecs) from Earth and orbiting Proxima Centauri, the closest star to the Sun. The discovery of exoplanets has intensified interest in the search for extraterrestrial life. There is special interest in planets that orbit in a star's habitable zone, where it is possible for liquid water, a prerequisite for life on"
"Proxima Centauri Proxima Centauri (), or Alpha Centauri C, is a red dwarf, a small low-mass star, about from the Sun in the constellation of Centaurus. It was discovered in 1915 by Robert Innes and is the nearest-known star to the Sun. With a quiescent apparent magnitude of 11.13, it is too faint to be seen with the naked eye. Proxima Centauri forms a third component of the Alpha Centauri system, currently with a separation of about and an orbital period of 550,000 years. At present Proxima is 2.18° to the southwest of Alpha Centauri. Because of Proxima Centauri's proximity"
"approach to the Sun) is estimated to have occurred around September 2010. Aphelion (furthest distance from the Sun) is estimated to have occurred around February 2016. , the asteroid is estimated to be from Earth. Perihelion (closest approach to the Sun) may not occur again until August 2021. Orbits computed with only a handful of observations can be unreliable. Short observation arcs can result in computer generated orbits rejecting some data unnecessarily. The 2018 JPL orbit determination shows a semi-major axis of 4.9 AU (albeit with a large 20 AU uncertainty) which would be near Jupiter's orbit. Such an orbit"
"to as ""volatiles"". The distance from Earth to the Sun is . For comparison, the radius of the Sun is . Thus, the Sun occupies 0.00001% (10 %) of the volume of a sphere with a radius the size of Earth's orbit, whereas Earth's volume is roughly one millionth (10) that of the Sun. Jupiter, the largest planet, is from the Sun and has a radius of , whereas the most distant planet, Neptune, is from the Sun. With a few exceptions, the farther a planet or belt is from the Sun, the larger the distance between its orbit and"
"Alpha Centauri Alpha Centauri (α Centauri, abbreviated Alpha Cen or α Cen) is the closest star system to the Solar System at from the Sun. It is a triple star system, consisting of three stars: Alpha Centauri A (officially Rigil Kentaurus), Alpha Centauri B (officially Toliman), and Alpha Centauri C (officially Proxima Centauri). Alpha Centauri A and B are Sun-like stars (Class G and K), and together they form the binary star Alpha Centauri AB. To the naked eye, the two main components appear as a single star with an apparent magnitude of −0.27, forming the brightest point of light"
"Wisp or Light Sail type concepts). Such a system could grow organically if space-based solar power became a significant component of Earth's energy mix. Consumer demand for a multi-terawatt system would automatically create the necessary multi-million ton/year logistical system. Distances between the planets in the Solar System are often measured in astronomical units (AU), defined as the average distance between the Sun and Earth, some . Venus, the closest other planet to Earth is (at closest approach) 0.28 AU away. Neptune, the farthest planet from the Sun, is 29.8 AU away. As of January 2018, Voyager 1, the farthest man-made"
"the Sun, which it orbits every 87.97 days. Kepler-9d Kepler-9d, formerly known as KOI-377.03, is a planet in orbit around the sunlike star Kepler-9. Initially discovered by Kepler spacecraft, a terrestrial planet-searching satellite built and operated by NASA, Kepler-9d is most likely a Super-Earth, with an estimated radius approximately 60% larger than that of Earth's, although its exact mass cannot be determined. Kepler-9d orbits Kepler-9 every 1.56 days at a distance of .0273 AU from its star, an extremely close distance. Although Kepler-9d is the closest planet to its star in its system, it is named Kepler-9d instead of Kepler-9b"
"close as to the Sun at its perihelion and take it as far away as at its aphelion. The aphelion, or farthest point from the Sun, would be in the general direction of the constellation of Taurus, whereas the perihelion, the nearest point to the Sun, would be in the general direction of the southerly areas of Serpens (Caput), Ophiuchus, and Libra. Brown thinks that if Planet Nine is confirmed to exist, a probe could fly by it in as little as 20 years with a powered slingshot around the Sun. The planet is estimated to have 10 times the"
"Neptune Neptune is the eighth and farthest known planet from the Sun in the Solar System. In the Solar System, it is the fourth-largest planet by diameter, the third-most-massive planet, and the densest giant planet. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times the mass of Earth and slightly larger than Neptune. Neptune orbits the Sun once every 164.8 years at an average distance of . It is named after the Roman god of the sea and has the astronomical symbol ♆, a stylised version of the"
"the Sun. Wolf 359 Wolf 359 is a red dwarf star located in the constellation Leo, near the ecliptic. At a distance of approximately 7.9 light years from Earth, it has an apparent magnitude of 13.54 and can only be seen with a large telescope. Wolf 359 is one of the nearest stars to the Sun; only the Alpha Centauri system (including Proxima Centauri), Barnard's Star and the brown dwarfs Luhman 16 and WISE 0855−0714 are known to be closer. Its proximity to Earth has led to its mention in several works of fiction. Wolf 359 is one of the"
"constellation Cassiopeia, similar to that of Achernar from Earth. Proxima Centauri Proxima Centauri (), or Alpha Centauri C, is a red dwarf, a small low-mass star, about from the Sun in the constellation of Centaurus. It was discovered in 1915 by Robert Innes and is the nearest-known star to the Sun. With a quiescent apparent magnitude of 11.13, it is too faint to be seen with the naked eye. Proxima Centauri forms a third component of the Alpha Centauri system, currently with a separation of about and an orbital period of 550,000 years. At present Proxima is 2.18° to the"
"Sun, it is around 9,160 light-years distant from Earth. AO Cassiopeiae is a binary system composed of an O8 main sequence star and an O9.2 bright giant that respectively weigh anywhere between 20.30 and 57.75 times and 14.8 and 31.73 times the mass of the Sun. The two massive stars are so close to each other they distort each other into egg-shapes. Tycho Brahe's supernova was visible within Cassiopeia, and the star Tycho G is suspected of being the donor of the material that triggered that explosion. If the Earth's Sun could be observed from α Centauri, the closest star"
"are easier to detect. On November 4, 2013, astronomers reported, based on ""Kepler"" data, that there could be as many as 40 billion Earth-sized planets orbiting in the habitable zones of Sun-like stars and red dwarfs in the Milky Way. 11 billion of these may be orbiting Sun-like stars. Proxima Centauri b, located about 4.2 light-years (1.3 parsecs) from Earth in the constellation of Centaurus, is the nearest known exoplanet, and is orbiting in the habitable zone of its star. The CHZ is also of particular interest to the emerging field of habitability of natural satellites, because planetary-mass moons in"
"observable from the Solar System. Like the other planets of the system, the planet has a high maximum eccentricity of 0.28, but the lowest in that system. Kepler-20e Kepler-20e is an exoplanet orbiting Kepler-20. The planet is notable as it is the first planet with a smaller radius than Earth found orbiting a Sun-like star. The planet is second-closest to the star after Kepler-20b, and at , it is far too hot to have liquid water on its surface. Along with the other four planets in the system, Kepler-20e was announced on 20 December 2011. With a semimajor axis of"
"than the distance from the Sun to Mercury. Its mass makes it more likely to be a Class II or Class III planet in the Sudarsky model. The presence of surface liquid water is possible on sufficiently massive satellites should they exist. Gliese 876 e, discovered in 2010, has a mass similar to that of the planet Uranus and its orbit takes 124 days to complete. Gliese 876 Gliese 876 is a red dwarf approximately 15 light-years away from Earth in the constellation of Aquarius. It is the one of the closest known stars to the Sun confirmed to possess"
"Kepler-20f Kepler-20f (also known by its Kepler Object of Interest designation ""KOI-70.05"") is an exoplanet orbiting the Sun-like star Kepler-20, the second outermost of five such planets discovered by NASA's ""Kepler"" spacecraft. It is located approximately 929 light-years (285 parsecs, or about km) from Earth in the constellation Lyra. The exoplanet was found by using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured. The planet is notable as it has the closest radius to Earth known so far. Kepler-20f is very likely (>95% chance) a rocky"
"approach of the other star, orbital stability is not guaranteed. Whether planets might form in binaries at all had long been unclear, given that gravitational forces might interfere with planet formation. Theoretical work by Alan Boss at the Carnegie Institution has shown that gas giants can form around stars in binary systems much as they do around solitary stars. One study of Alpha Centauri, the nearest star system to the Sun, suggested that binaries need not be discounted in the search for habitable planets. Centauri A and B have an 11 AU distance at closest approach (23 AU mean), and"
"billion Earth-sized planets orbiting in the habitable zones of sun-like stars and red dwarf stars within the Milky Way Galaxy. 11 billion of these estimated planets may be orbiting sun-like stars. Since there are about 100 billion stars in the galaxy, this implies is roughly 0.4. The nearest planet in the habitable zone is Proxima Centauri b, which is as close as about 4.2 light-years away. The consensus at the Green Bank meeting was that had a minimum value between 3 and 5. Dutch science journalist Govert Schilling has opined that this is optimistic. Even if planets are in the"
"parsecs' (5.41 light-years) distance. The Sun and Alpha Centauri are, respectively, the next closest systems. From Barnard's Star, the Sun would appear on the diametrically opposite side of the sky at coordinates RA=, Dec=, in the eastern part of the constellation Monoceros. The absolute magnitude of the Sun is 4.83, and at a distance of 1.834 parsecs, it would be a first-magnitude star, as Pollux is from the Earth. Barnard's Star Barnard's Star is a very-low-mass red dwarf about 6 light-years away from Earth in the constellation of Ophiuchus. It is the fourth nearest known individual star to the Sun"
"travels relative to other nearby stars. This motion is towards a point in the constellation Hercules, near the star Vega. Of the 50 nearest stellar systems within 17 light-years from Earth (the closest being the red dwarf Proxima Centauri at approximately 4.2 light-years), the Sun ranks fourth in mass. The Sun orbits the center of the Milky Way, and it is presently moving in the direction of the constellation of Cygnus. A simple model of the motion of a star in the galaxy gives the galactic coordinates , , and as: where , , and are the respective velocities with"
"0.995 AU (or 700,000 km) closer to the star than Earth to the Sun, but its orbital eccentricity is much higher compared to Earth. At periastron, the planet’s closest distance to the star is 0.708 AU, which is slightly closer to the star than Venus to the Sun. At apastron, the planet’s farthest distance to the star is 1.283 AU, which is more than halfway between the orbits of Earth and Mars. 30 Arietis Bb 30 Arietis Bb (sometimes abbreviated 30 Ari Bb) is an extrasolar planet which orbits the F-type main sequence star 30 Arietis B, located in a"
"planet to exist around 1 AU. Solar analog Solar-type star, solar analogs (also analogues), and solar twins are stars that are particularly similar to the Sun. The stellar classification is a hierarchy with solar twin being most like the Sun followed by solar analog and then solar-type. Observations of these stars are important for understanding better the properties of the Sun in relation to other stars and the habitability of planets. Defining the three categories by their similarity to the Sun reflects the evolution of astronomical observational techniques. Originally, solar-type was the closest that similarity to the Sun could be"
"negligible because of the huge distances between the stars. For example, the nearest star to the Sun is Proxima Centauri, about or 30 million (3) solar diameters away. If the Sun were a ping-pong ball, Proxima Centauri would be a pea about away, and the Milky Way would be about 30 million km ( million mi) wide. Although stars are more common near the centers of each galaxy, the average distance between stars is still 160 billion (1.6) km (100 billion mi). That is analogous to one ping-pong ball every . Thus, it is extremely unlikely that any two stars"
"and direction to those of Alpha Centauri AB, suggesting that Proxima Centauri is part of the Alpha Centauri system and slightly closer to Earth than Alpha Centauri AB. Lying away, Proxima Centauri is the nearest star to the Sun. All current derived distances for the three stars are from the parallaxes obtained from the Hipparcos star catalogue (HIP) and the Hubble Space Telescope. All components of Alpha Centauri display significant proper motion against the background sky. Over centuries, this causes their apparent positions to slowly change. Proper motion was unknown to ancient astronomers. Most assumed that the stars are immortal"