"7 light-years away. Compared to many other planetary systems, the Solar System stands out in lacking planets interior to the orbit of Mercury. The known Solar System also lacks super-Earths (Planet Nine could be a super-Earth beyond the known Solar System). Uncommonly, it has only small rocky planets and large gas giants; elsewhere planets of intermediate size are typical—both rocky and gas—so there is no ""gap"" as seen between the size of Earth and of Neptune (with a radius 3.8 times as large). Also, these super-Earths have closer orbits than Mercury. This led to hypothesis that all planetary systems start"
"Earth's year of 365 days. Its orbital radius is at 0.0875 AU, or 8.75% the distance between Earth and the Sun. While this is quite close, the star LHS 1140 is so dim that the planet only get 0.41 times the incident flux of Earth at this distance. With an albedo of 0, LHS 1140 b has an equilibrium temperature of , compared to Earth's at . If LHS 1140 b has an albedo similar to that of Earth, the equilibrium temperature would be even lower, at . However, with a greenhouse effect at least as strong as Earth's LHS"
"Kepler-421b to be a real planet without additional confirmation methods. Kepler-421b is slightly larger than Uranus although its mass is not known. Kepler-421b Kepler-421b is an exoplanet that, as of July 2014, has the longest known year of any transiting planet (704 days), although not as long as the planets that have been directly imaged, or many of the planets found by the radial-velocity method, or as long as some transiting planet candidates which are listed as planets in the Extrasolar Planets Encyclopaedia (KIC 5010054 b etc.). It is the first transiting-planet found near the snow-line. Normally, at least three"
"Gliese 581. Just as Earth's Moon always presents the same face to the Earth, the length of Gliese 581g's sidereal day would then precisely match the length of its year, meaning it would be permanently light on one half and permanently dark on the other half of its surface. An atmosphere that is dense will circulate heat, potentially allowing a wide area on the surface to be habitable. For example, Venus has a solar rotation rate approximately 117 times slower than Earth's, producing prolonged days and nights. Despite the uneven distribution of sunlight over time intervals shorter than several months,"
"revolution with respect to its apsides. The orbit of the Earth is elliptical; the extreme points, called apsides, are the perihelion, where the Earth is closest to the Sun (January 3 in 2011), and the aphelion, where the Earth is farthest from the Sun (July 4 in 2011). The anomalistic year is usually defined as the time between perihelion passages. Its average duration is days (365 d 6 h 13 min 52.6 s) (at the epoch J2011.0). The draconic year, draconitic year, eclipse year, or ecliptic year is the time taken for the Sun (as seen from the Earth) to"
"the innermost planet in our Solar System, Mercury, takes 88 days to orbit at a distance of 0.38 AU. The eccentricity and inclination of K2-148b's orbit are currently unknown. K2-148b orbits a late-K dwarf star known as K2-148, or EPIC 220194974. It is 63% the radius, 65% the mass, and 10% the luminosity of the Sun, with a temperature of 4079 K and an unknown age. For comparison, the Sun has a temperature of 5778 K and is 4.5 billion years old. It is orbited by a slightly smaller M0.5V red dwarf known as EPIC 220194953 at a distance of"
"Galactic year The galactic year, also known as a cosmic year, is the duration of time required for the Sun to orbit once around the center of the Milky Way Galaxy. Estimates of the length of one orbit range from 225 to 250 million terrestrial years. The Solar System is traveling at an average speed of 828,000 km/h (230 km/s) or 514,000 mph (143 mi/s) within its trajectory around the galactic center, a speed at which an object could circumnavigate the Earth's equator in 2 minutes and 54 seconds; that speed corresponds to approximately 1/1300 of the speed of light."
"slowest rotation period of any known object in the Solar System. A Venusian sidereal day thus lasts more than a Venusian year (243 versus 224.7 Earth days). However, the length of a solar day on Venus is significantly shorter than the sidereal day; to an observer on the surface of Venus, the time from one sunrise to the next would be 116.75 days. Therefore, the slow Venerian rotation rate would result in extremely long days and nights, similar to the day-night cycles in the polar regions of earth, only shorter. The slow rotation might also account for the lack of"
"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 galactic year provides a conveniently usable unit for depicting cosmic and geological time periods together. By contrast, a ""billion-year"" scale does not allow for useful discrimination between geologic events, and a ""million-year"" scale requires some rather large numbers. The following list assumes that 1 galactic year is 225 million years. Galactic year The galactic year, also known as a cosmic year, is the duration of time required for the Sun to orbit once around the center of the Milky Way Galaxy. Estimates of the length of one orbit range from 225 to 250 million terrestrial years. The Solar System"
"a minute longer than a solar year.) The sidereal year of 365.25636 days is only valid for stars on the ecliptic (the apparent path of the Sun across the sky), whereas Sirius's displacement ~40˚ below the ecliptic, its proper motion, and the wobbling of the celestial equator cause the period between its heliacal risings to be almost exactly 365.25 days long instead. This steady loss of one relative day every four years over the course of the 365-day calendar meant that the ""wandering"" day would return to its original place relative to the solar and Sothic year after precisely 1461"
"way of the Ram/sun (Osirus worship) was removed, yet is of Yahweh/Yahuwa/Jehovah. Therefore, we give glory to itself; one far greater than the greatest things we know. The sun has 365 windows through which it emerges; 182 in the east, 182 in the west, and 1 in the middle, the place of its first entrance. The course described by it in a year is traversed by the moon in 30 days. The solar year is longer by 11 days than the lunar year (Yer. R. H. ii. 58a). The sun completes its course in 12 months; Jupiter, in 12 years;"
"and intense storms. Some astronomers believe that it plays an important protecting role in using its massive gravity to capture or expel from the solar system many comets and asteroids that would otherwise threaten Earth and the inner planets. Jupiter takes 11.9 years to orbit the Sun, spending almost an earth year (361 days) in each sign of the zodiac. Furthermore, Jupiter is usually the fourth-brightest object in the sky (after the Sun, the Moon and Venus). Astrologically speaking, Jupiter is associated with the principles of growth, expansion, prosperity, and good fortune. Jupiter governs long distance and foreign travel, big"
"eventually leading to confusion about when to undertake activities dependent on weather, ecology, or hours of daylight. A solar year is actually slightly shorter than 365 days and 6 hours (365.25 days), which had been known since the 2nd century BC when Hipparchus stated that it lasted 365 + − days, but this was ignored by Julius Caesar and his astronomical adviser Sosigenes. The Gregorian calendar corrected this by adopting the length of the tropical year stated in three medieval sources, the Alfonsine tables, De Revolutionibus, and the Prutenic Tables, truncated to two sexagesimal places, 365 days or 365 +"
"Kepler-421b Kepler-421b is an exoplanet that, as of July 2014, has the longest known year of any transiting planet (704 days), although not as long as the planets that have been directly imaged, or many of the planets found by the radial-velocity method, or as long as some transiting planet candidates which are listed as planets in the Extrasolar Planets Encyclopaedia (KIC 5010054 b etc.). It is the first transiting-planet found near the snow-line. Normally, at least three transits are required to confirm a planet. Due to very high signal to noise ratio, only two transits were sufficient to validate"
"through the zodiac constellations over thousands and tens of thousands of years. As on Earth, the effect of precession causes the north and south celestial poles to move in a very large circle, but on Mars the cycle is 175,000 Earth years rather than 26,000 years as on Earth. As on Earth, there is a second form of precession: the point of perihelion in Mars's orbit changes slowly, causing the anomalistic year to differ from the sidereal year. However, on Mars, this cycle is 83,600 years rather than 112,000 years as on Earth. On both Earth and Mars, these two"
"extended to 366 once every four years, without exception, so have a mean year of 365.25 days. As solar calendars became more accurate, they evolved into two types. If the position of the earth in its orbit around the sun is reckoned with respect to the equinox, the point at which the orbit crosses the celestial equator, then its dates accurately indicate the seasons, that is, they are synchronized with the declination of the sun. Such a calendar is called a tropical solar calendar . The duration of the ""mean"" calendar year of such a calendar approximates some form of"
"Earth and the Sun. For comparison, Mercury, our Solar System's innermost planet, takes 88 days to orbit at a distance of about 0.38 AU. The size of TRAPPIST-1 and the close orbit of TRAPPIST-1d around it means that the star as seen from the planet appears 5.5 times as large as the Sun from the Earth. While a planet at TRAPPIST-1d's distance from our Sun would be a scorched world, the low luminosity of TRAPPIST-1 means that the planet gets only 1.043 times the sunlight that Earth receives, placing it within the inner part of the conservative habitable zone. The"
"365.2425 days, which matches the 4/100/400 leap year rules of the commonly used Gregorian calendar. Additional adjustments to the calendar over intervals this long are unavoidable, as the actual year is currently slightly shorter (about 365.242374 days) than assumed, the length of Earth's orbit around the Sun changes over time (tropical years are currently becoming shorter at a rate of about 0.53 seconds per century), and in any case, all of these times far exceed the likely existence of the Earth. So the year numbers should be considered approximate. Time zones and Daylight saving time can cause trouble in computer"
"the heavens. In Hawaiian, its name is ""Hele‘ekala"", a loanword for the discoverer Herschel. In Māori, its name is ""Whērangi"". Uranus orbits the Sun once every 84 years. Its average distance from the Sun is roughly . The difference between its minimum and maximum distance from the Sun is 1.8 AU, larger than that of any other planet, though not as large as that of dwarf planet Pluto. The intensity of sunlight varies inversely with the square of distance, and so on Uranus (at about 20 times the distance from the Sun compared to Earth) it is about 1/400 the"
"vernal equinox year is 668.5907 sols in length (which corresponds to 686.86 days on Earth). The basic intercalation formula therefore allocates six 669-sol years and four 668-sol years to each Martian decade. The former (still called leap years even though they are more common than non-leap years) are years that are either odd (not evenly divisible by 2) or else are evenly divisible by 10, producing 6,686 sols per ten years (668.6 sols per year). A 1998 iteration of the Darian calendar made years divisible by 100 common years, but years divisible by 500 stay leap years. However, this static"
"have a planetary system—echoing the fate of the Solar System in a few billion years as the Sun ages and becomes a giant. Conversely, HD 45364 is a star 107 light-years distant that is a little smaller and cooler than the Sun, of spectral type G8V, which has two planets discovered in 2008. With orbital periods of 228 and 342 days, the planets have a 3:2 orbital resonance, which helps stabilise the system. HD 47186 is another sunlike star with two planets; the inner—HD 47186 b—takes four days to complete an orbit and has been classified as a Hot Neptune,"
"in every 400 years, so that the average length of a calendar year is 365 97/400 days; while in the Persian calendar every eighth leap-cycle is extended to 5 years, making the average 365 8/33 days, shorter than the Gregorian average by one day every 13200 years. The date of the solstice is not the same as the date of the latest sunrise and both are not the same as the date of earliest sunset. Because the Earth is moving along its solar orbital path, for each solar day the Earth has to do more than one full rotation. Because"
"400 years has exactly 146,097 days, i.e. exactly 20,871 weeks, one can say that the Gregorian so-called solar cycle lasts 400 years. Calendar years are usually marked by Dominical letters indicating the first Sunday in a new year, thus the term solar cycle can also refer to a repeating sequence of Dominical letters. Unless a year is not a leap year due to Gregorian exceptions, a sequence of calendars is reused every 28 years. The name ""solar cycle"" comes from ""Sunday"", the traditional first day of the week. The dominical letter in the Julian calendar depends only on the remainder"
"about 25,700 years. The Galactic year is the time it takes Earth's solar system to revolve once around the galactic center. It comprises roughly 230 million Earth years. A seasonal year is the time between successive recurrences of a seasonal event such as the flooding of a river, the migration of a species of bird, the flowering of a species of plant, the first frost, or the first scheduled game of a certain sport. All of these events can have wide variations of more than a month from year to year. In the International System of Quantities the symbol for"
"Venus Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. It has the longest rotation period (243 days) of any planet in the Solar System and rotates in the opposite direction to most other planets (meaning the Sun would rise in the west and set in the east). It does not have any natural satellites. It is named after the Roman goddess of love and beauty. It is the second-brightest natural object in the night sky after the Moon, reaching an apparent magnitude of −4.6 – bright enough to cast shadows at night and, rarely,"
"Sun is about 4.6 billion years old and has a surface temperature of 5778 K. Gliese 876 b is in a 1:2:4 Laplace resonance with the inner planet Gliese 876 c and the outer planet Gliese 876 e: in the time it takes planet e to complete one orbit, planet b completes two and planet c completes four. This is the second known example of a Laplace resonance, the first being Jupiter's moons Io, Europa and Ganymede. As a result, the orbital elements of the planets change fairly rapidly as they dynamically interact with one another. The planet's orbit has"
"Earth's mean distance. Its length is: The Besselian year is a tropical year that starts when the (fictitious) mean Sun reaches an ecliptic longitude of 280°. This is currently on or close to January 1. It is named after the 19th-century German astronomer and mathematician Friedrich Bessel. The following equation can be used to compute the current Besselian epoch (in years): The TT subscript indicates that for this formula, the Julian date should use the Terrestrial Time scale, or its predecessor, ephemeris time. The exact length of an astronomical year changes over time. Mean year lengths in this section are"
"point on Earth. However, there are physical and astronomical effects that change that picture. Namely, atmospheric refraction allows the Sun to be still visible even when it physically sets below the horizon. For that reason, average daytime (disregarding cloud effects) is longest in polar areas, where the apparent Sun spends the most time around the horizon. Places on the Arctic Circle have the longest total annual daytime, 4,647 hours, while the North Pole receives 4,575. Because of elliptic nature of the Earth's orbit, the Southern Hemisphere is not symmetrical: the Antarctic Circle, with 4,530 hours of daylight, receives five days"
"heights. Venus Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. It has the longest rotation period (243 days) of any planet in the Solar System and rotates in the opposite direction to most other planets (meaning the Sun would rise in the west and set in the east). It does not have any natural satellites. It is named after the Roman goddess of love and beauty. It is the second-brightest natural object in the night sky after the Moon, reaching an apparent magnitude of −4.6 – bright enough to cast shadows at night and,"
"by the Apollo program. </math>, where ""m"" is the mass of Earth, ""a"" is an astronomical unit, and ""M"" is the mass of the Sun. So the radius in AU is about formula_1.</ref> Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago. Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year."
"but still large enough to raise its surface temperature far above the calculated equilibrium temperature. The orbit of TRAPPIST-1c is very close to its host star. One year on this planet lasts a mere 2.42 days (58 hours), a fraction as long as that of our Solar System's innermost planet, Mercury. The planet orbits at a distance of 0.0158 AU, which is about 1.6% the distance between Earth and the Sun. At this proximity, TRAPPIST-1c is most likely tidally locked. However, due to the small size of its host star, the planet only receives about 2.1 times the sunlight as"
"standard. It is a solar calendar that is designed to maintain synchrony with the mean tropical year . It has a cycle of 400 years (146,097 days). Each cycle repeats the months, dates, and weekdays. The average year length is 146,097/400 = = 365.2425 days per year, a close approximation to the mean tropical year . The Gregorian calendar is a reformed version of the Julian calendar. By the time of the reform in 1582, the date of the vernal equinox had shifted about 10 days, from about March 21 at the time of the First Council of Nicaea in"