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76-454: The ultraviolet radiation in sunlight has both positive and negative health effects, as it is both a requisite for vitamin D 3 synthesis and a mutagen . Sunlight takes about 8.3 minutes to reach Earth from the surface of the Sun. A photon starting at the center of the Sun and changing direction every time it encounters a charged particle would take between 10,000 and 170,000 years to get to

152-409: A broad range of wavelengths: X-rays , ultraviolet , visible light , infrared , and radio waves . Different depths in the photosphere have different temperatures, and this partially explains the deviations from a black-body spectrum. There is also a flux of gamma rays from the quiescent sun, obeying a power law between 0.5 and 2.6 TeV . Some gamma rays are caused by cosmic rays interacting with

228-520: A day apart, with Gamme starting first, but completing according to plan the last few kilometers together. As Gamme traveled alone he thus simultaneously became the first to complete the task solo. On 28 December 2018, Captain Lou Rudd became the first Briton to cross the Antarctic unassisted via the south pole, and the second person to make the journey in 56 days. On 10 January 2020, Mollie Hughes became

304-454: A higher elevation). The South Pole is at an altitude of 9,200 feet (2,800 m) but feels like 11,000 feet (3,400 m). Centripetal force from the spin of the planet throws the atmosphere toward the equator. The South Pole is colder than the North Pole primarily because of the elevation difference and for being in the middle of a continent. The North Pole is a few feet from sea level in

380-654: A key role in recombinational repair of DNA damage. Thus the level of terrestrial solar UV-B radiation likely affects genome stability in plants. Vitamin D3 Too Many Requests If you report this error to the Wikimedia System Administrators, please include the details below. Request from 172.68.168.226 via cp1108 cp1108, Varnish XID 767701038 Upstream caches: cp1108 int Error: 429, Too Many Requests at Fri, 29 Nov 2024 05:52:25 GMT South Pole The South Pole , also known as

456-561: A less clear, and probably more complicated fashion, with Earth's climate responses than earlier assumed, fueling broad avenues of new research in "the connection of the Sun and stratosphere, troposphere, biosphere, ocean, and Earth's climate". The spectrum of surface illumination depends upon solar elevation due to atmospheric effects, with the blue spectral component dominating during twilight before and after sunrise and sunset, respectively, and red dominating during sunrise and sunset. These effects are apparent in natural light photography where

532-541: A longitude is desired, it may be given as 0°. At the South Pole, all directions face north. For this reason, directions at the Pole are given relative to "grid north", which points northward along the prime meridian . Along tight latitude circles, clockwise is east, and counterclockwise is west, opposite to the North Pole . The Geographic South Pole is presently located on the continent of Antarctica , although this has not been

608-428: A nearly perfect circle, and at other times stretching out to an orbital eccentricity of 5% (currently 1.67%). As the orbital eccentricity changes, the average distance from the Sun (the semimajor axis does not significantly vary, and so the total insolation over a year remains almost constant due to Kepler's second law , where A {\displaystyle A} is the "areal velocity" invariant. That is,

684-463: A number of states in the world. For many people with light skin, one purpose for sunbathing is to darken one's skin color (get a sun tan), as this is considered in some cultures to be attractive, associated with outdoor activity, vacations/holidays , and health. Some people prefer naked sunbathing so that an "all-over" or "even" tan can be obtained, sometimes as part of a specific lifestyle. Controlled heliotherapy , or sunbathing, has been used as

760-568: A perpendicular surface at sea level. The illumination of a horizontal surface will be considerably less than this if the Sun is not very high in the sky. Averaged over a day, the highest amount of sunlight on a horizontal surface occurs in January at the South Pole (see insolation ). Dividing the irradiance of 1,050 W/m by the size of the Sun's disk in steradians gives an average radiance of 15.4 MW per square metre per steradian. (However,

836-528: A risk factor for skin cancer, "sun avoidance may carry more of a cost than benefit for over-all good health". A study found that there is no evidence that UV reduces lifespan in contrast to other risk factors like smoking, alcohol and high blood pressure. Elevated solar UV -B doses increase the frequency of DNA recombination in Arabidopsis thaliana and tobacco ( Nicotiana tabacum ) plants. These increases are accompanied by strong induction of an enzyme with

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912-420: A small sign; these are repositioned each year in a ceremony on New Year's Day to compensate for the movement of the ice. The sign records the respective dates that Roald Amundsen and Robert F. Scott reached the Pole, followed by a short quotation from each man, and gives the elevation as "9,301 FT. ". A new marker stake is designed and fabricated each year by staff at the site. The Ceremonial South Pole

988-479: A treatment for psoriasis and other maladies. Skin tanning is achieved by an increase in the dark pigment inside skin cells called melanocytes , and is an automatic response mechanism of the body to sufficient exposure to ultraviolet radiation from the Sun or from artificial sunlamps. Thus, the tan gradually disappears with time, when one is no longer exposed to these sources. The ultraviolet radiation in sunlight has both positive and negative health effects, as it

1064-488: Is a measure of flux density , is the amount of incoming solar electromagnetic radiation per unit area that would be incident on a plane perpendicular to the rays, at a distance of one astronomical unit (AU) (roughly the mean distance from the Sun to Earth). The "solar constant" includes all types of solar radiation, not just the visible light . Its average value was thought to be approximately 1,366 W/m, varying slightly with solar activity , but recent recalibrations of

1140-410: Is ample sunlight. Some common places for sunbathing include beaches , open air swimming pools , parks , gardens , and sidewalk cafes . Sunbathers typically wear limited amounts of clothing or some simply go nude . For some, an alternative to sunbathing is the use of a sunbed that generates ultraviolet light and can be used indoors regardless of weather conditions. Tanning beds have been banned in

1216-585: Is an area set aside for photo opportunities at the South Pole Station . It is located some meters from the Geographic South Pole, and consists of a metallic sphere on a short barber pole, surrounded by the flags of the original Antarctic Treaty signatory states . The tent was erected by the Norwegian expedition led by Roald Amundsen on its arrival on 14 December 1911. It is currently buried beneath

1292-457: Is because the US flies its resupply missions (" Operation Deep Freeze ") out of McMurdo Station , which is supplied from Christchurch , New Zealand. Due to its exceptionally harsh climate, there are no native resident plants or animals at the South Pole. Off-course south polar skuas and snow petrels are occasionally seen there. In 2000 it was reported that microbes had been detected living in

1368-432: Is both a principal source of vitamin D 3 and a mutagen . A dietary supplement can supply vitamin D without this mutagenic effect, but bypasses natural mechanisms that would prevent overdoses of vitamin D generated internally from sunlight. Vitamin D has a wide range of positive health effects, which include strengthening bones and possibly inhibiting the growth of some cancers. Sun exposure has also been associated with

1444-569: Is fueled by light from the Sun. Most autotrophs , such as plants, use the energy of sunlight, combined with carbon dioxide and water, to produce simple sugars—a process known as photosynthesis . These sugars are then used as building-blocks and in other synthetic pathways that allow the organism to grow. Heterotrophs , such as animals, use light from the Sun indirectly by consuming the products of autotrophs, either by consuming autotrophs, by consuming their products, or by consuming other heterotrophs. The sugars and other molecular components produced by

1520-441: Is given to a good approximation by where dn=1 on January 1; dn=32 on February 1; dn=59 on March 1 (except on leap years, where dn=60), etc. In this formula dn–3 is used, because in modern times Earth's perihelion , the closest approach to the Sun and, therefore, the maximum E ext occurs around January 3 each year. The value of 0.033412 is determined knowing that the ratio between the perihelion (0.98328989 AU) squared and

1596-460: Is needed; only a handful of objects in the Solar System have been discovered that are known to orbit farther than such a distance, among them 90377 Sedna and (87269) 2000 OO 67 . On Earth, the solar radiation varies with the angle of the Sun above the horizon , with longer sunlight duration at high latitudes during summer, varying to no sunlight at all in winter near the pertinent pole. When

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1672-407: Is partially buried due to snow storms, and the entrance to the dome had to be regularly bulldozed to uncover it. More recent buildings are raised on stilts so that the snow does not build up against their sides. In most places on Earth, local time is determined by longitude , such that the time of day is more-or-less synchronised to the perceived position of the Sun in the sky (for example, at midday

1748-549: The Earth's atmosphere spans a range of 100  nm to about 1  mm (1,000,000 nm). This band of significant radiation power can be divided into five regions in increasing order of wavelengths : Tables of direct solar radiation on various slopes from 0 to 60 degrees north latitude, in calories per square centimetre, issued in 1972 and published by Pacific Northwest Forest and Range Experiment Station, Forest Service, U.S. Department of Agriculture, Portland, Oregon, USA, appear on

1824-593: The Geographic South Pole or Terrestrial South Pole , is the southernmost point on Earth and lies antipodally on the opposite side of Earth from the North Pole , at a distance of 20,004 km (12,430 miles) in all directions. It is one of the two points where Earth's axis of rotation intersects its surface. Situated on the continent of Antarctica , it is the site of the United States Amundsen–Scott South Pole Station , which

1900-597: The International Geophysical Year and has been continuously staffed since then by research and support personnel. After Amundsen and Scott, the next people to reach the South Pole overland (albeit with some air support) were Edmund Hillary (4 January 1958) and Vivian Fuchs (19 January 1958) and their respective parties, during the Commonwealth Trans-Antarctic Expedition . There have been many subsequent expeditions to arrive at

1976-532: The electromagnetic spectrum . Although the radiation created in the solar core consists mostly of x rays , internal absorption and thermalization convert these super-high-energy photons to lower-energy photons before they reach the Sun's surface and are emitted out into space. As a result, the photosphere of the Sun does not emit much X radiation ( solar X-rays ), although it does emit such "hard radiations" as X-rays and even gamma rays during solar flares . The quiet (non-flaring) Sun, including its corona , emits

2052-468: The ice sheet is actually near sea level. The polar ice sheet is moving at a rate of roughly 10 m (33 ft) per year in a direction between 37° and 40° west of grid north, down towards the Weddell Sea . Therefore, the position of the station and other artificial features relative to the geographic pole gradually shift over time. The Geographic South Pole is marked by a stake in the ice alongside

2128-665: The Amundsen–Scott South Pole Station was −12.3 °C (9.9 °F) on Christmas Day, 2011, and the lowest was −82.8 °C (−117.0 °F) on 23 June 1982 (for comparison, the lowest temperature directly recorded anywhere on earth was −89.2 °C (−128.6 °F) at Vostok Station on 21 July 1983, though −93.2 °C (−135.8 °F) was measured indirectly by satellite in East Antarctica between Dome A and Dome F in August 2010 ). Mean annual temperature at

2204-627: The Geographic South Pole were the Norwegian Roald Amundsen and his party on 14 December 1911. Amundsen named his camp Polheim and the entire plateau surrounding the Pole King Haakon VII Vidde in honour of King Haakon VII of Norway . Robert Falcon Scott returned to Antarctica with his second expedition, the Terra Nova Expedition , initially unaware of Amundsen's secretive expedition. Scott and four other men reached

2280-710: The Pole at a depth of 17 m (56 ft) below the present surface. A flagpole erected at the South Geographical Pole in December 1965 by the First Argentine Overland Polar Expedition has been designated a Historic Site or Monument (HSM 1) following a proposal by Argentina to the Antarctic Treaty Consultative Meeting . In 1820, several expeditions claimed to have been the first to have sighted Antarctica, with

2356-423: The South Pole became more accessible to non-government expeditions. On 30 December 1989, Arved Fuchs and Reinhold Messner were the first to traverse Antarctica via the South Pole without animal or motorized help, using only skis and the help of wind. Two women, Victoria E. Murden and Shirley Metz, reached the pole by land on 17 January 1989. The fastest unsupported journey to the Geographic South Pole from

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2432-430: The South Pole by surface transportation, including those by Havola, Crary , and Fiennes . The first group of women to reach the pole were Pam Young, Jean Pearson, Lois Jones , Eileen McSaveney , Kay Lindsay, and Terry Tickhill in 1969. In 1978–79, Michele Eileen Raney became the first woman to winter at the South Pole. Subsequent to the establishment, in 1987, of the logistic support base at Patriot Hills Base Camp ,

2508-476: The South Pole is –49.5 °C (–57.1 °F). The South Pole has an ice cap climate ( Köppen climate classification EF ). It resembles a desert, receiving very little precipitation. Air humidity is near zero. However, high winds can cause the blowing of snowfall, and the accumulation of snow amounts to about 7 cm (2.8 in) per year. The former dome seen in pictures of the Amundsen–Scott station

2584-503: The South Pole on 17 January 1912, thirty-four days after Amundsen. On the return trip, Scott and his four companions all died of starvation and extreme cold. In 1914 Ernest Shackleton's Imperial Trans-Antarctic Expedition set out with the goal of crossing Antarctica via the South Pole, but his ship, the Endurance , was frozen in pack ice and sank 11 months later. The overland journey was never made. US Admiral Richard Evelyn Byrd , with

2660-507: The Sun at the zenith depends on the distance to the Sun and thus on the time of year. It is about 3.3% higher than average in January and 3.3% lower in July (see below). If the extraterrestrial solar radiation is 1,367 watts per square meter (the value when the Earth–Sun distance is 1 astronomical unit ), then the direct sunlight at Earth's surface when the Sun is at the zenith is about 1,050 W/m, but

2736-443: The Sun is roughly perceived to be at its highest). This line of reasoning fails at the South Pole, where the Sun is seen to rise and set only once per year with solar elevation varying only with day of the year, not time of day. There is no a priori reason for placing the South Pole in any particular time zone, but as a matter of practical convenience the Amundsen–Scott South Pole Station keeps New Zealand Time (UTC+12/UTC+13). This

2812-525: The UK in 2006. She made the journey in 39 days 9 hours 33 minutes. She started on 19 November 2006 and finished on 28 December 2006. In the 2011–12 summer, separate expeditions by Norwegian Aleksander Gamme and Australians James Castrission and Justin Jones jointly claimed the first unsupported trek without dogs or kites from the Antarctic coast to the South Pole and back. The two expeditions started from Hercules Inlet

2888-526: The aim of travelling as far south as possible, and on 31 December 1902, reached 82°16′ S. Shackleton later returned to Antarctica as leader of the British Antarctic Expedition ( Nimrod Expedition ) in a bid to reach the Pole. On 9 January 1909, with three companions, he reached 88°23' S – 112 miles (180 km) from the Pole ;– before being forced to turn back. The first men to reach

2964-494: The aphelion (1.01671033 AU) squared should be approximately 0.935338. The solar illuminance constant ( E sc ), is equal to 128×10  lux . The direct normal illuminance ( E dn ), corrected for the attenuating effects of the atmosphere is given by: where c is the atmospheric extinction and m is the relative optical airmass . The atmospheric extinction brings the number of lux down to around 100,000 lux. The total amount of energy received at ground level from

3040-553: The approximately 23.5° tilt of the earth's axis. Much of the sunlight that does reach the surface is reflected by the white snow. This lack of warmth from the sun, combined with the high altitude (about 2,800 metres (9,200 ft)), means that the South Pole has one of the coldest climates on Earth (though it is not quite the coldest; that record goes to the region in the vicinity of the Vostok Station , also in Antarctica, which lies at

3116-467: The assistance of his first pilot Bernt Balchen , became the first person to fly over the South Pole on 29 November 1929. It was not until 31 October 1956 that humans once again set foot at the South Pole, when a party led by Admiral George J. Dufek of the US Navy landed there in an R4D-5L Skytrain ( C-47 Skytrain ) aircraft. The US Amundsen–Scott South Pole Station was established by air over 1956–1957 for

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3192-415: The autotrophs are then broken down, releasing stored solar energy, and giving the heterotroph the energy required for survival. This process is known as cellular respiration . In prehistory , humans began to further extend this process by putting plant and animal materials to other uses. They used animal skins for warmth, for example, or wooden weapons to hunt. These skills allowed humans to harvest more of

3268-422: The brightness of sunlight, many people wear sunglasses . Cars , many helmets and caps are equipped with visors to block the Sun from direct vision when the Sun is at a low angle. Sunshine is often blocked from entering buildings through the use of walls , window blinds , awnings , shutters , curtains , or nearby shade trees . Sunshine exposure is needed biologically for the production of Vitamin D in

3344-446: The case for all of Earth's history because of continental drift . It sits atop a featureless, barren, windswept and icy plateau at an altitude of 2,835 m (9,301 ft) above sea level, and is located about 1,300 km (810 mi) from the nearest open sea at the Bay of Whales . The ice is estimated to be about 2,700 m (8,900 ft) thick at the Pole, so the land surface under

3420-445: The change in solar energy in summer and winter. For example, at latitudes of 65 degrees, this can vary by more than 25% as a result of Earth's orbital variation. Because changes in winter and summer tend to offset, the change in the annual average insolation at any given location is near zero, but the redistribution of energy between summer and winter does strongly affect the intensity of seasonal cycles. Such changes associated with

3496-443: The direct radiation is not blocked by clouds, it is experienced as sunshine . The warming of the ground (and other objects) depends on the absorption of the electromagnetic radiation in the form of heat . The amount of radiation intercepted by a planetary body varies inversely with the square of the distance between the star and the planet. Earth's orbit and obliquity change with time (over thousands of years), sometimes forming

3572-566: The extra UV consisting of biologically damaging short-wave ultraviolet. Direct sunlight has a luminous efficacy of about 93  lumens per watt of radiant flux . This is higher than the efficacy (of source) of artificial lighting other than LEDs , which means using sunlight for illumination heats up a room less than fluorescent or incandescent lighting. Multiplying the figure of 1,050 watts per square meter by 93 lumens per watt indicates that bright sunlight provides an illuminance of approximately 98,000 lux ( lumens per square meter) on

3648-524: The first being the Russian expedition led by Fabian Gottlieb von Bellingshausen and Mikhail Lazarev . The first landing was probably just over a year later when English-born American captain John Davis , a sealer, set foot on the ice. The basic geography of the Antarctic coastline was not understood until the mid-to-late 19th century. American naval officer Charles Wilkes claimed (correctly) that Antarctica

3724-434: The integration over the orbital period (also invariant) is a constant. If we assume the solar radiation power  P as a constant over time and the solar irradiation given by the inverse-square law , we obtain also the average insolation as a constant. However, the seasonal and latitudinal distribution and intensity of solar radiation received at Earth's surface does vary. The effect of Sun angle on climate results in

3800-405: The intensity of sunlight using a sunshine recorder , pyranometer , or pyrheliometer . To calculate the amount of sunlight reaching the ground, both the eccentricity of Earth's elliptic orbit and the attenuation by Earth's atmosphere have to be taken into account. The extraterrestrial solar illuminance ( E ext ), corrected for the elliptic orbit by using the day number of the year (dn),

3876-456: The light within a specific sensitivity range. Many animals (including humans) have a sensitivity range of approximately 400–700 nm, and given optimal conditions the absorption and scattering by Earth's atmosphere produces illumination that approximates an equal-energy illuminant for most of this range. The useful range for color vision in humans, for example, is approximately 450–650 nm. Aside from effects that arise at sunset and sunrise,

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3952-499: The middle of an ocean. In midsummer, as the sun reaches its maximum elevation of about 23.5 degrees, high temperatures at the South Pole in January average at −25.9 °C (−15 °F). As the six-month "day" wears on and the sun gets lower, temperatures drop as well: they reach −55 °C (−67 °F) around sunset (late March) and sunrise (late September). In midwinter, the average temperature remains steady at around −60 °C (−76 °F). The highest temperature ever recorded at

4028-414: The ocean is 24 days and one hour from Hercules Inlet and was set in 2011 by Norwegian adventurer Christian Eide, who beat the previous solo record set in 2009 by American Todd Carmichael of 39 days and seven hours, and the previous group record also set in 2009 of 33 days and 23 hours. The fastest solo, unsupported and unassisted trek to the south pole by a female was performed by Hannah McKeand from

4104-462: The only listed carcinogens that are known to have health benefits, and a number of public health organizations state that there needs to be a balance between the risks of having too much sunlight or too little. There is a general consensus that sunburn should always be avoided. Epidemiological data shows that people who have more exposure to sunlight have less high blood pressure and cardiovascular-related mortality. While sunlight (and its UV rays) are

4180-406: The past 400 years or cosmogenic radionuclides for going back 10,000 years. Such reconstructions have been done. These studies show that in addition to the solar irradiance variation with the solar cycle (the (Schwabe) cycle), the solar activity varies with longer cycles, such as the proposed 88 year (Gleisberg cycle), 208 year (DeVries cycle) and 1,000 year (Eddy cycle). The solar constant

4256-400: The principal source of illumination is sunlight as mediated by the atmosphere. While the color of the sky is usually determined by Rayleigh scattering , an exception occurs at sunset and twilight. "Preferential absorption of sunlight by ozone over long horizon paths gives the zenith sky its blueness when the sun is near the horizon". The Sun may be said to illuminate , which is a measure of

4332-438: The radiance at the center of the sun's disk is somewhat higher than the average over the whole disk due to limb darkening .) Multiplying this by π gives an upper limit to the irradiance which can be focused on a surface using mirrors: 48.5 MW/m. The spectrum of the Sun's solar radiation can be compared to that of a black body with a temperature of about 5,800  K (see graph). The Sun emits EM radiation across most of

4408-442: The redistribution of solar energy are considered a likely cause for the coming and going of recent ice ages (see: Milankovitch cycles ). Space-based observations of solar irradiance started in 1978. These measurements show that the solar constant is not constant. It varies on many time scales, including the 11-year sunspot solar cycle. When going further back in time, one has to rely on irradiance reconstructions, using sunspots for

4484-568: The relevant satellite observations indicate a value closer to 1,361 W/m is more realistic. Since 1978, a series of overlapping NASA and ESA satellite experiments have measured total solar irradiance (TSI) – the amount of solar radiation received at the top of Earth's atmosphere – as 1.365 kilo⁠watts per square meter (kW/m). TSI observations continue with the ACRIMSAT /ACRIM3, SOHO /VIRGO and SORCE /TIM satellite experiments. Observations have revealed variation of TSI on many timescales, including

4560-495: The remnants of ancient plant and animal matter, formed using energy from sunlight and then trapped within Earth for millions of years. The effect of sunlight is relevant to painting , evidenced for instance in works of Édouard Manet and Claude Monet on outdoor scenes and landscapes. Many people find direct sunlight to be too bright for comfort; indeed, looking directly at the Sun can cause long-term vision damage. To compensate for

4636-479: The skin, a vital compound needed to make strong bone and muscle in the body. In many world religions, such as Hinduism , the Sun is considered to be a god , as it is the source of life and energy on Earth. The Sun was also considered to be a god in Ancient Egypt . Sunbathing is a popular leisure activity in which a person sits or lies in direct sunshine. People often sunbathe in comfortable places where there

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4712-412: The snow and ice in the vicinity of the Pole. It has been designated a Historic Site or Monument (HSM 80), following a proposal by Norway to the Antarctic Treaty Consultative Meeting . The precise location of the tent is unknown, but based on calculations of the rate of movement of the ice and the accumulation of snow, it is believed, as of 2010, to lie between 1.8 and 2.5 km (1.1 and 1.5 miles) from

4788-445: The solar atmosphere, but this does not explain these findings. The only direct signature of the nuclear processes in the core of the Sun is via the very weakly interacting neutrinos . Although the solar corona is a source of extreme ultraviolet and X-ray radiation, these rays make up only a very small amount of the power output of the Sun (see spectrum at right). The spectrum of nearly all solar electromagnetic radiation striking

4864-490: The solar light it receives. The actual illumination of the surface is about 14,000 lux, comparable to that on Earth "in the daytime with overcast clouds". Sunlight on Mars would be more or less like daylight on Earth during a slightly overcast day, and, as can be seen in the pictures taken by the rovers, there is enough diffuse sky radiation that shadows would not seem particularly dark. Thus, it would give perceptions and "feel" very much like Earth daylight. The spectrum on

4940-574: The solar magnetic cycle and many shorter periodic cycles. TSI provides the energy that drives Earth's climate, so continuation of the TSI time-series database is critical to understanding the role of solar variability in climate change. Since 2003, the SORCE Spectral Irradiance Monitor (SIM) has monitored Spectral solar irradiance (SSI) – the spectral distribution of the TSI. Data indicate that SSI at UV (ultraviolet) wavelength corresponds in

5016-507: The southern point of the two points where Earth's axis of rotation intersects its surface (the other being the Geographic North Pole ). However, Earth's axis of rotation is actually subject to very small "wobbles" ( polar motion ), so this definition is not adequate for very precise work. The geographic coordinates of the South Pole are usually given simply as 90°S, since its longitude is geometrically undefined and irrelevant. When

5092-406: The spectral composition changes primarily in respect to how directly sunlight is able to illuminate. When illumination is indirect, Rayleigh scattering in the upper atmosphere will lead blue wavelengths to dominate. Water vapour in the lower atmosphere produces further scattering and ozone, dust and water particles will also absorb particular wavelengths. The existence of nearly all life on Earth

5168-596: The sunlight than was possible through glycolysis alone, and human population began to grow. During the Neolithic Revolution , the domestication of plants and animals further increased human access to solar energy. Fields devoted to crops were enriched by inedible plant matter, providing sugars and nutrients for future harvests. Animals that had previously provided humans with only meat and tools once they were killed were now used for labour throughout their lives, fueled by grasses inedible to humans. Fossil fuels are

5244-481: The surface is slightly redder than that on Earth, due to scattering by reddish dust in the Martian atmosphere. For comparison, sunlight on Saturn is slightly brighter than Earth sunlight at the average sunset or sunrise. Even on Pluto, the sunlight would still be bright enough to almost match the average living room. To see sunlight as dim as full moonlight on Earth, a distance of about 500 AU (~69  light-hours )

5320-451: The surface. Sunlight is a key factor in photosynthesis , the process used by plants and other autotrophic organisms to convert light energy , normally from the Sun, into chemical energy that can be used to synthesize carbohydrates and fuel the organisms' activities. Daylighting is the natural lighting of interior spaces by admitting sunlight. Solar irradiance is the solar energy available from sunlight. Researchers can measure

5396-472: The timing of melatonin synthesis, maintenance of normal circadian rhythms , and reduced risk of seasonal affective disorder . Long-term sunlight exposure is known to be associated with the development of skin cancer , skin aging , immune suppression , and eye diseases such as cataracts and macular degeneration . Short-term overexposure is the cause of sunburn , snow blindness , and solar retinopathy . UV rays, and therefore sunlight and sunlamps, are

5472-414: The total amount (direct and indirect from the atmosphere) hitting the ground is around 1,120 W/m. In terms of energy, sunlight at Earth's surface is around 52 to 55 percent infrared (above 700 nm ), 42 to 43 percent visible (400 to 700 nm), and 3 to 5 percent ultraviolet (below 400 nm). At the top of the atmosphere, sunlight is about 30% more intense, having about 8% ultraviolet (UV), with most of

5548-527: The web. Different bodies of the Solar System receive light of an intensity inversely proportional to the square of their distance from Sun. A table comparing the amount of solar radiation received by each planet in the Solar System at the top of its atmosphere: The actual brightness of sunlight that would be observed at the surface also depends on the presence and composition of an atmosphere . For example, Venus's thick atmosphere reflects more than 60% of

5624-428: The youngest person to ski to the pole, aged 29. During winter (May through August), the South Pole receives no sunlight at all, and is completely dark apart from moonlight. In summer (November through February), the sun is continuously above the horizon and appears to move in a counter-clockwise circle. However, it is always low in the sky, reaching a maximum of approximately 23.5° around the December solstice because of

5700-528: Was a new continent, basing the claim on his exploration in 1839–40, while James Clark Ross , in his expedition of 1839–1843, hoped that he might be able to sail all the way to the South Pole; He was unsuccessful. British explorer Robert Falcon Scott on the Discovery Expedition of 1901–1904 was the first to attempt to find a route from the Antarctic coastline to the South Pole. Scott, accompanied by Ernest Shackleton and Edward Wilson , set out with

5776-525: Was established in 1956 and has been permanently staffed since that year. The Geographic South Pole is distinct from the South Magnetic Pole , the position of which is defined based on Earth's magnetic field . The South Pole is the center of the Southern Hemisphere . 90°S 0°E  /  90°S 0°E  / -90; 0 For most purposes, the Geographic South Pole is defined as

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