is the sun a planet or a star

At the photosphere, the temperature has dropped to 5,700 K and the density to only 0.2 g/m3 (about 1/6,000 the density of air at sea level). The Sun will spend a total of approximately 10 billion years as a main-sequence star. [125] The Sun is gradually becoming hotter during its time on the main sequence, because the helium atoms in the core occupy less volume than the hydrogen atoms that were fused. The Sun is a star. at the point around which the Sun circulates is. Planets, on the other hand, form when material in the disk around a pre-existing star begins to condense around rock/ice cores. When using an attenuating filter to view the Sun, the viewer is cautioned to use a filter specifically designed for that use. [51] Theoretical models of the Sun's interior indicate a maximum power density, or energy production, of approximately 276.5 watts per cubic metre at the center of the core,[76] which is about the same power density inside a compost pile. 201–244 in, produced by previous generations of stars, formation and evolution of the Solar System, Formation and evolution of the Solar System, "Proposals for the masses of the three largest asteroids, the Moon–Earth mass ratio and the Astronomical Unit", Celestial Mechanics and Dynamical Astronomy, "The new solar abundances – Part I: the observations", The Astrophysical Journal Supplement Series, "Solar System Exploration: Planets: Sun: Facts & Figures", "Report Of The IAU/IAG Working Group On Cartographic Coordinates And Rotational Elements Of The Planets And Satellites: 2000", "First Ever STEREO Images of the Entire Sun", "The origin and evolution of the solar system", "Astronomers Had it Wrong: Most Stars are Single", "Equinoxes, Solstices, Perihelion, and Aphelion, 2000–2020", "The solar oblateness and its relationship with the structure of the tachocline and of the Sun's subsurface", "Sun is the most perfect sphere ever observed in nature", "Construction of a Composite Total Solar Irradiance (TSI) Time Series from 1978 to present", "Reference Solar Spectral Irradiance: Air Mass 1.5", "Dr Karl's Great Moments In Science: Lazy Sun is less energetic than compost", "Solar System Abundances and Condensation Temperatures of the Elements", "Abundances and Condensation Temperatures of the Elements", "Abundances of singly ionized elements of the iron group in the Sun", Monthly Notices of the Royal Astronomical Society, "Tracking solar gravity modes: the dynamics of the solar core", "Experimental evidence of neutrinos produced in the CNO fusion cycle in the Sun", "Table of temperatures, power densities, luminosities by radius in the Sun", "Lazy Sun is less energetic than compost", "Lecture 11 – Stellar Structure I: Hydrostatic Equilibrium", "The solar tachocline: Formation, stability and its role in the solar dynamo", "Solar Physics: From the Deep Interior to the Hot Corona", "A Survey of the Solar Atmospheric Models", Bulletin of the Astronomical Society of India, "New Light on the Heart of Darkness of the Solar Chromosphere", "The role of helium in the outer solar atmosphere", "Heating of the solar and stellar coronae: a review", "Solar wind and interplanetary magnetic filed: A tutorial", "Modeling the heliospheric current sheet: Solar cycle variations", "The Distortion of the Heliosphere: Our Interstellar Magnetic Compass", "NASA Satellites Capture Start of New Solar Cycle", "Modeling the Sun's Large-Scale Magnetic Field during the Maunder Minimum", "Astronomers Observe New Type Of Magnetic Explosion On The Sun", "Estimating the Sun's radiative output during the Maunder Minimum", "Solar Resonant Diffusion Waves as a Driver of Terrestrial Climate Change", Journal of Atmospheric and Solar–Terrestrial Physics, "Red Giant Stars: Facts, Definition & the Future of the Sun", Annual Review of Astronomy and Astrophysics, "First results from SPIFFI. [203] Long-duration viewing of the direct Sun with the naked eye can begin to cause UV-induced, sunburn-like lesions on the retina after about 100 seconds, particularly under conditions where the UV light from the Sun is intense and well focused;[204][205] conditions are worsened by young eyes or new lens implants (which admit more UV than aging natural eyes), Sun angles near the zenith, and observing locations at high altitude. In order, from the closest to the Sun, these planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. 2 The sun is the real star of the show—literally! The enormous effect of the Sun on Earth has been recognized since prehistoric times, and the Sun has been regarded by some cultures as a solar deity. All these words stem from Proto-Germanic *sunnōn. The heat and light from the Sun is felt and seen on Earth. In 1666, Isaac Newton observed the Sun's light using a prism, and showed that it is made up of light of many colors. In its core, it fuses hydrogen into helium, as all stars do for the majority of their lives, in order to generate enough pressure to avoid collapsing under its own gravity. / {\displaystyle (U(0),V(0),W(0))=(10.00,5.25,7.17)} A planet is a ball of inert material (silica for example) that receives light and heat from a star. Herschel wedges, also called Solar Diagonals, are effective and inexpensive for small telescopes. The photosphere is not fully ionized—the extent of ionization is about 3%, leaving almost all of the hydrogen in atomic form. κ This motion is towards a point in the constellation Hercules, near the star Vega. For some periods of several decades, the motion is rather regular, forming a trefoil pattern, whereas between these periods it appears more chaotic. [69], The thermal columns of the convection zone form an imprint on the surface of the Sun giving it a granular appearance called the solar granulation at the smallest scale and supergranulation at larger scales. A fifth of Brits (20%) believe the Sun is a planet. [82], The visible surface of the Sun, the photosphere, is the layer below which the Sun becomes opaque to visible light. It was adopted as the Sabbath day by Christians who did not have a Jewish background. These meteorites are thought to retain the composition of the protostellar Sun and are thus not affected by settling of heavy elements. Let's put your love and knowledge of astronomy to the test. {\displaystyle \Omega _{0}=A-B} [146] For the sun, the present values of U, V, and W are estimated as / [23][24] This is ultimately related to the word for "sun" in other branches of the Indo-European language family, though in most cases a nominative stem with an l is found, rather than the genitive stem in n, as for example in Latin sōl, Greek ἥλιος hēlios, Welsh haul and Russian солнце solntse (pronounced sontse), as well as (with *l > r) Sanskrit स्वर svár and Persian خور xvar. [99] In contrast, it takes only 2.3 seconds for the neutrinos, which account for about 2% of the total energy production of the Sun, to reach the surface. [115] [211], Ultraviolet light from the Sun has antiseptic properties and can be used to sanitize tools and water. It has been argued that the Sun's passage through the higher density spiral arms often coincides with mass extinctions on Earth, perhaps due to increased impact events. [33][34] This is about 13 billion times brighter than the next brightest star, Sirius, which has an apparent magnitude of −1.46. The Sun is 109 times wider than the Earth and 330,000 times as massive. [201][202] UV exposure gradually yellows the lens of the eye over a period of years, and is thought to contribute to the formation of cataracts, but this depends on general exposure to solar UV, and not whether one looks directly at the Sun. [80] The transition region is not easily visible from Earth's surface, but is readily observable from space by instruments sensitive to the extreme ultraviolet portion of the spectrum. She did research studying the wind patterns on Jupiter while at Cornell. [27], The English weekday name Sunday stems from Old English Sunnandæg "sun's day", a Germanic interpretation of the Latin phrase diēs sōlis, itself a translation of the Greek ἡμέρα ἡλίου hēmera hēliou "day of the sun". It was destroyed by atmospheric re-entry in 2005. [100], Neutrinos are also released by the fusion reactions in the core, but, unlike photons, they rarely interact with matter, so almost all are able to escape the Sun immediately. The thermal pulses become larger each time, with the later pulses pushing the luminosity to as much as 5,000 times the current level and the radius to over 1 AU. In its core, it fuses hydrogen into helium, as all stars do for the majority of their lives, in order to generate enough pressure to avoid collapsing under its own gravity. , The distance of stars is expressed in light-years, i.e. The Sun’s surface area is 11,990 times that of the Earth’s. The electrically conducting solar wind plasma carries the Sun's magnetic field into space, forming what is called the interplanetary magnetic field. Why is the sun not considered a planet? The Sun is a star. 0 The solar magnetic field extends well beyond the Sun itself. [88], The chromosphere, transition region, and corona are much hotter than the surface of the Sun. Ultraviolet light is strongly attenuated by Earth's ozone layer, so that the amount of UV varies greatly with latitude and has been partially responsible for many biological adaptations, including variations in human skin color in different regions of the Earth.[212]. [92] Originally intended to serve a two-year mission, a mission extension through 2012 was approved in October 2009. Regarding shape, stars appear as a dot while planets appear spherical. (Beginner), How does the Sun compare to other stars? The Sun's color is white, with a CIE color-space index near (0.3, 0.3), when viewed from space or when the Sun is high in the sky, and the Solar radiance per wavelength peaks in the green portion of the spectrum. During partial eclipses most sunlight is blocked by the Moon passing in front of the Sun, but the uncovered parts of the photosphere have the same surface brightness as during a normal day. The central mass became so hot and dense that it eventually initiated nuclear fusion in its core. She is now an 8th grade Earth Sciences teacher in Natick, MA. [46] The atmosphere in particular filters out over 70% of solar ultraviolet, especially at the shorter wavelengths. W (Intermediate), What do I need to do to become an astronomer? The sunlight that is destined for the eyepiece is reflected from an unsilvered surface of a piece of glass. [70] Only 0.8% of the energy generated in the Sun comes from another sequence of fusion reactions called the CNO cycle, though this proportion is expected to increase as the Sun becomes older. Only a very small fraction of the incident light is reflected. Watch this to learn more. Two identical spacecraft were launched into orbits that cause them to (respectively) pull further ahead of and fall gradually behind Earth. However, it turns out our Milky Way galaxy can do one better: A planet orbiting a star in a TRIPLE-sun system has been discovered by Nasa. This differential rotation is caused by convective motion due to heat transport and the Coriolis force due to the Sun's rotation. It is calculated that the Sun will become sufficiently large to engulf the current orbits of Mercury and Venus, and render Earth uninhabitable – but not for about five billion years. π Solar is a word that pertains to Sun and all things related to it. This makes it the 20th closest star to our Solar System. (Intermediate), What will happen to Earth's tides as the moon moves away from us? [192], All these satellites have observed the Sun from the plane of the ecliptic, and so have only observed its equatorial regions in detail. B From the reign of Elagabalus in the late Roman Empire the Sun's birthday was a holiday celebrated as Sol Invictus (literally "Unconquered Sun") soon after the winter solstice, which may have been an antecedent to Christmas. [178] However, it would be Albert Einstein who would provide the essential clue to the source of the Sun's energy output with his mass–energy equivalence relation E = mc2. Over the past 4.6 billion years, the amount of helium and its location within the Sun has gradually changed. [107][108], During the solar cycle's declining phase, energy shifts from the internal toroidal magnetic field to the external poloidal field, and sunspots diminish in number and size. The Sun today is roughly halfway through the most stable part of its life. Its gravity holds the solar system together, keeping everything – from the biggest planets to the smallest particles of debris – in its orbit. An entire compilation of SuperMarioLogan's running gag in the SML series: "The Sun is a Planet/Star". Once the material diffusively and radiatively cools just beneath the photospheric surface, its density increases, and it sinks to the base of the convection zone, where it again picks up heat from the top of the radiative zone and the convective cycle continues. [93] The interplanetary magnetic field is much stronger than the dipole component of the solar magnetic field. From the Greek helios comes the rare adjective heliac /ˈhiːliæk/. The Dwarf Star reflects the light of the sun. [159] In addition, Alfvén waves do not easily dissipate in the corona. These could provide a better explanation of the ice ages than the Milankovitch cycles.[118][119]. In defining a planet the said it had to be a celestial body that orbited the sun, is round or nearly round – and here’s the important bit – “clears the neighbourhood” around its orbit. One astronomical unit (about 150,000,000 km; 93,000,000 mi) is defined as the mean distance of the Sun's center to Earth's center, though the distance varies as Earth moves from perihelion in January to aphelion in July. Because they radiate energy, stars are very bright objects. [123] As one fragment of the cloud collapsed it also began to rotate due to conservation of angular momentum and heat up with the increasing pressure. [187] The Skylab space station, launched by NASA in 1973, included a solar observatory module called the Apollo Telescope Mount that was operated by astronauts resident on the station.

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