90 Fun Facts About The Sun

What type of celestial object is the Sun?

The Sun is a star — specifically a G-type main-sequence star (G2V). It is the closest star to Earth and the center of our solar system.

Approximately how long does it take sunlight to reach Earth?

Light from the Sun takes approximately 8 minutes and 20 seconds to travel the roughly 150 million kilometers (93 million miles) to Earth.

What is the primary gas that makes up the Sun?

The Sun is roughly three-quarters hydrogen by mass, and that hydrogen is the fuel for the fusion reactions in its core. Heavier elements such as oxygen, carbon, neon and iron together make up only a small fraction.

What process powers the Sun and produces its energy?

The Sun is powered by nuclear fusion, where hydrogen atoms fuse together to form helium in its core, releasing enormous amounts of energy in the process.

What color would the Sun appear if viewed from space, without atmospheric interference?

The Sun actually emits white light. It appears yellow or orange from Earth's surface because the atmosphere scatters shorter (blue) wavelengths, making the remaining light look yellowish.

In ancient Egyptian mythology, who was the sun god?

Ra (also spelled Re) was the ancient Egyptian sun god and one of the most important deities in the Egyptian pantheon. He was believed to sail across the sky each day in a solar boat.

Which Jesuit astronomer feuded bitterly over priority in the discovery of sunspots?

Scheiner published his sunspot observations under the pseudonym 'Apelles' and clashed with a rival for years over who saw them first. Neither knew Johannes Fabricius had already published on sunspots in 1611.

What is the approximate surface temperature of the Sun?

The photosphere sits at about 5,500°C (around 5,778 K, or 9,940°F), while the core is around 15 million°C.

How many Earths could fit inside the Sun?

The Sun is about 109 Earths across, so roughly 1.3 million Earths fit by volume; by mass it takes only 330,000, because the Sun is far less dense than Earth.

What event occurs when the Moon passes between the Sun and Earth, blocking the Sun's light?

A solar eclipse occurs when the Moon passes between the Sun and Earth, casting a shadow on Earth. In a total solar eclipse, the Moon completely blocks the Sun's disk.

Which layer of the Sun flashes reddish-pink for a few seconds at total eclipses?

The chromosphere sits between the visible surface and the corona and glows a distinctive reddish-pink from hydrogen emission. It is normally drowned out by the surface's glare and appears only when the Moon blocks the disk.

What is the approximate age of the Sun?

The Sun is approximately 4.6 billion years old. It formed from a collapsing cloud of gas and dust (a solar nebula) and is roughly halfway through its main-sequence life.

What will the Sun eventually become at the end of its life?

The Sun is not massive enough to go supernova. In about 5 billion years, it will expand into a red giant, shed its outer layers to form a planetary nebula, and the remaining core will become a white dwarf.

Roughly how long does a typical coronal mass ejection take to reach Earth?

A coronal mass ejection typically needs about 1 to 3 days to reach Earth; even the fastest, moving at over 2,000 km/s, take well over half a day.

What percentage of the solar system's total mass does the Sun contain?

The Sun contains approximately 99.86% of the total mass of the entire solar system. Jupiter, the largest planet, accounts for most of the remaining mass.

In Greek mythology, who was the god of the Sun?

Helios was the Greek Titan who drove the Sun's four-horse chariot across the sky each day; his siblings were Selene, the Moon, and Eos, the Dawn.

What is the visible surface of the Sun called?

The photosphere is the visible surface of the Sun — the layer that emits the light we see. It is about 500 km thick and has a temperature of approximately 5,500°C.

How long is one complete solar cycle (sunspot cycle)?

The solar cycle lasts approximately 11 years, during which the Sun's activity rises and falls. Sunspot numbers increase to a solar maximum and then decrease to a solar minimum over this period.

What is the approximate escape velocity at the Sun's surface?

The Sun's escape velocity is about 618 km/s, some 55 times Earth's 11.2 km/s; a rocket would need that speed at the photosphere to coast away forever.

Which of NASA’s spacecraft, launched in 2018, was built to fly through the Sun’s corona?

Parker Solar Probe launched in August 2018 and has flown within about 6.2 million km of the Sun's surface, closer than any spacecraft before it.

How long does the Sun take to complete one orbit around the centre of the Milky Way?

The Sun drags the whole Solar System around the galaxy at roughly 230 km/s, and one lap — a galactic year — takes about 220 to 250 million years. It has managed around 20 laps since it formed.

Roughly how fast does the solar wind typically stream past Earth?

The solar wind typically streams past Earth at about 400 km/s, with fast streams reaching 750 km/s; at that pace a parcel of it takes around four days to arrive.

Roughly how strong is gravity at the Sun's surface compared with Earth's?

Surface gravity on the Sun is about 28 times Earth's, roughly 274 m/s², so an 80 kg person would weigh more than two tonnes at the photosphere.

In which arm of the Milky Way does the Sun sit?

The Sun sits in the Orion Arm, also called the Local Arm, a minor spur between the larger Sagittarius and Perseus arms, about 26,000 light-years from the galactic centre.

What was the Carrington Event of 1859?

The biggest geomagnetic storm on record: the CME hit so hard that telegraph lines sparked and offices caught fire, and auroras glowed as far south as the Caribbean.

How long does the Sun's equator take to spin once around?

The equator laps the poles: 25.6 days versus 33.5. A solid ball could not do that; a ball of plasma can.

Where does the Sun's solar wind give out and interstellar space begin?

The heliopause is where the solar wind can no longer push back the interstellar medium; Voyager 1 crossed it in August 2012, about 121 AU from the Sun.

What is the Latin word for the Sun?

Sol is the Latin word for the Sun; it survives in solar, solstice (from sol plus sistere, 'to stand still'), solarium and parasol.

Which spacecraft, launched in December 1995, was built to observe the Sun from the L1 point?

SOHO, the Solar and Heliospheric Observatory, launched on 2 December 1995 and took station at the L1 Lagrange point between Earth and the Sun, far outliving its planned two-year mission.

Roughly how long does a neutrino produced in the Sun's core take to reach the surface and escape?

Neutrinos barely interact with matter, so they stream straight out of the Sun in a couple of seconds and reach Earth about eight minutes later. Trillions pass through your body every second without you noticing.

About how much brighter is the Sun today than when it formed?

The Sun is about 30% brighter than when it formed 4.6 billion years ago; the 'faint young Sun paradox' asks why early Earth was not frozen solid.

Which scientist observed sunspots by telescope around 1612 and argued they were on the Sun itself?

Galileo tracked sunspots as they crossed the solar disk and argued they lay on the Sun itself rather than being small bodies passing in front of it. Thomas Harriot and Johannes Fabricius made telescopic sunspot observations around the same time.

What is the solar constant, the solar energy per square metre at Earth's distance?

The solar constant, also called total solar irradiance, is about 1,361 W/m² at the top of Earth's atmosphere — the power per square metre arriving from the Sun at Earth's mean distance.

By about how many degrees is the Sun's rotation axis tilted from the ecliptic?

The Sun's spin axis is tilted about 7° — precisely 7.25° — from the ecliptic, which is why Earth sees slightly more of its north pole each September and of its south pole each March.

Roughly how long could Kelvin and Helmholtz's gravitational contraction theory have kept the Sun shining?

Gravitational contraction could power the Sun for only about 20 million years, far short of the hundreds of millions of years geologists read in the rocks. The conflict was resolved only once fusion was understood in the 1930s.

What is helioseismology?

Helioseismology studies the Sun's interior by analyzing acoustic waves (pressure oscillations) that propagate through and across the Sun's surface. It has revealed details about the Sun's internal rotation, temperature, and composition.

What is the tachocline?

The tachocline is the thin boundary layer between the Sun's radiative zone (which rotates as a solid body) and the convective zone (which rotates differentially). It is believed to play a key role in generating the Sun's magnetic field.

What does the Babcock–Leighton mechanism explain?

The Babcock–Leighton dynamo treats the 11-year sunspot cycle as half of a 22-year magnetic cycle, in which energy sloshes between the Sun's toroidal and poloidal fields. The Sun's magnetic poles swap places every cycle.

Which ancient civilization built Stonehenge, partly aligned with the Sun's position during solstices?

Stonehenge was built by Neolithic and early Bronze Age peoples of Britain, primarily between 3000-2000 BCE. Its alignment with the sunrise on the summer solstice and sunset on the winter solstice suggests it served astronomical and ceremonial purposes.

Which element turned up in the Sun's spectrum before anyone found it on Earth?

An unexplained yellow line in the Sun's spectrum during the 1868 eclipse led Norman Lockyer to propose a new element, named from the Greek word for the Sun. It was not found on Earth until 1895, in a uranium mineral.

What 1990 probe used a Jupiter slingshot to fly over the Sun's poles?

Because it had to travel out to Jupiter, it could not run on solar panels and carried a nuclear power source instead. It was originally named Odysseus.

Which 1980 NASA solar satellite became the first to be repaired in orbit by astronauts?

Solar Maximum Mission launched in February 1980 and lost attitude control within months; in April 1984 Challenger astronauts captured and repaired it, the first in-orbit satellite repair.

How fast was the Parker Solar Probe moving at its December 2024 perihelion?

Parker Solar Probe hit about 690,000 km/h (191 km/s) at its 24 December 2024 perihelion — about 0.064% of light speed and faster than any earlier human-made object.

Which twin 1974–76 probes held the spacecraft speed record until 2018?

Helios 1 and 2, launched in 1974 and 1976 by West Germany with NASA, reached 252,792 km/h near perihelion, a record that stood until Parker Solar Probe in 2018.

Which NASA capsule carrying particles caught from the Sun crash-landed in Utah in 2004?

Genesis spent two years collecting solar-wind particles; in September 2004 its drogue parachute never deployed and it hit the Utah desert, yet enough clean material survived to meet the mission's major science goals.

India's first dedicated solar observatory, launched on a PSLV rocket in September 2023, carries what name?

Aditya-L1 is a coronagraphy spacecraft parked at the Sun–Earth Lagrange point 1 for an uninterrupted view of the Sun.

ESA's Solar Orbiter, launched 2020, tilts its orbit using flybys of which planet?

Each flyby cranks its orbital inclination toward 24 degrees, giving the first good look at the Sun's poles from out of the ecliptic plane.

In which year did NASA's twin STEREO spacecraft launch together on one rocket?

STEREO-A and STEREO-B launched together on 25 October 2006; one drifted ahead of Earth and one behind, and in February 2011 they imaged the entire Sun at once for the first time.

Japan's 1991 X-ray solar satellite Yohkoh has a name meaning what?

Yohkoh means 'sunbeam' in Japanese; known as Solar-A before launch, it imaged the X-ray corona for a full decade until 2001, and its successor Hinode means 'sunrise'.

The Solar Dynamics Observatory's Sun images appeared on what US item in 2021?

The US Postal Service's 2021 'Sun Science' Forever stamps used ten images from the Solar Dynamics Observatory, which has imaged the Sun since its February 2010 launch.

Which 1973 US space station carried the Apollo Telescope Mount solar observatory?

Skylab hosted three crews for about 24 weeks in total, with the Apollo Telescope Mount giving them a multi-spectral view of the Sun.

Which NASA series put probes 6 to 9 into solar orbit to monitor space weather?

Pioneer 6, 7, 8 and 9, launched between 1965 and 1968, formed the first network of solar-orbiting space-weather monitors; Pioneer 9 kept transmitting until May 1983.

Which Soviet craft first directly measured the stream of particles from the Sun, in 1959?

Luna 1, launched in January 1959, carried Konstantin Gringauz's ion traps, which registered the solar wind; Marcia Neugebauer's team confirmed it in 1962 with Mariner 2.

In the 1950s, Biermann inferred a particle stream from the Sun from what feature?

A comet's tail streams away from the Sun no matter which way the comet is moving, which sunlight pressure alone could not fully explain.

In which year did Voyager 2 cross the heliopause into interstellar space?

Voyager 2 crossed the heliopause on 5 November 2018 at about 119 AU, six years after Voyager 1; its still-working plasma instrument gave the first direct measurement of such a crossing.

What is the boundary where the Sun's outflowing particles abruptly slow, beyond Pluto?

At the termination shock the solar wind abruptly drops from supersonic to subsonic speed; beyond it lies the heliosheath, which the two Voyager probes spent years crossing before leaving the bubble.

The 4-metre Daniel K. Inouye Solar Telescope stands on which Hawaiian volcano?

The Daniel K. Inouye Solar Telescope stands at 3,000 m on Haleakalā, Maui; it released its first test images in January 2020 and is named after Hawaii's long-serving US senator.

Which German amateur astronomer first spotted the sunspot cycle, in 1843?

Heinrich Schwabe, a pharmacist by trade, had been hunting for a planet inside Mercury's orbit; after logging sunspots daily for 17 years he announced a roughly 10-year cycle in 1843.

The numbered sunspot cycles start from a cycle that began in which year?

Rudolf Wolf fixed the numbering in 1852, counting from the cycle that began in 1755; by that count the cycle that began in December 2019 is Solar Cycle 25.

Who showed in 1908 that sunspots are magnetised, the first magnetism found beyond Earth?

His later work on sunspot pair polarities, now Hale's law, revealed that the full magnetic cycle is 22 years, not 11.

What is the dark central part of a sunspot called?

The umbra is the sunspot's dark core, where the magnetic field is strongest and nearly vertical; at roughly 3,000–4,500 K it looks dark only by contrast with the 5,780 K photosphere.

The largest sunspots can reach diameters of roughly how many kilometres?

The largest sunspot groups stretch about 160,000 km, more than twelve Earths side by side; even an average spot is roughly as big as Earth, about 12,700 km across.

The earliest deliberate sunspot observation, from 364 BC, comes from which civilisation?

Chinese astronomer Gan De recorded a sunspot in 364 BC in his star catalogue; the I Ching, completed before 800 BC, holds an even older indirect record.

Solar flares are classed A, B, C, M or X by their peak flux in what kind of radiation?

Each letter is ten times the one before, measured by GOES weather satellites. The letters were picked to avoid clashing with older optical classes.

Which year's 'Halloween storms' produced a flare that saturated GOES detectors, later rated X45?

The flare of 4 November 2003 saturated the GOES detectors at X28 and was later estimated at about X45; the same Halloween storm series blacked out Malmö, Sweden, for an hour.

A huge solar storm in July 2012 missed Earth by roughly how much time?

The 23 July 2012 eruption tore through the part of Earth's orbit the planet had passed roughly a week to nine days earlier, and struck the STEREO-A spacecraft instead.

Which amateur astronomer independently saw the 1 September 1859 white-light flare alongside Carrington?

Richard Hodgson independently recorded the same white-light flash as Carrington on 1 September 1859, and both accounts appeared together in the Monthly Notices of the Royal Astronomical Society.

How long is the saros, the period after which a near-identical eclipse repeats?

A saros is 18 years and 11 days — 6,585.3 days; the extra third of a day means each repeat lands about 120 degrees of longitude further west.

What is the absolute maximum length of totality in a total eclipse?

The theoretical maximum for totality is about 7 minutes 32 seconds; the longest eclipse yet calculated, on 16 July 2186 over northern Guyana, will reach 7 minutes 29 seconds.

Before 2017, when had a total eclipse last crossed the whole United States coast to coast?

The 8 June 1918 eclipse ran from Washington state to Florida; the 2017 'Great American Eclipse' repeated the coast-to-coast feat from Oregon to South Carolina, while 1979's touched only the northwest.

The April 2024 eclipse that later swept from Texas to Canada hit its longest totality near Nazas, in which Mexican state?

Totality near Nazas, Durango, lasted 4 minutes 28 seconds, the longest of the 'Great North American Eclipse' that then swept from Texas to the Canadian Maritimes.

The 1919 relativity eclipse was observed from Sobral, Brazil, and which African island?

Arthur Eddington led the party on Príncipe, in the Gulf of Guinea; measuring how much the Sun's gravity bent starlight confirmed general relativity and made Einstein famous overnight.

Who catalogued the dark absorption lines in the Sun's spectrum in 1814?

Joseph von Fraunhofer, a Bavarian optician, mapped hundreds of the dark lines in 1814, after Wollaston had noticed about half a dozen in 1802, turning them into a tool for reading stellar chemistry.

Whose 1925 thesis showed stars are overwhelmingly made of the lightest element?

Cecilia Payne's 1925 Harvard thesis found stars are mostly hydrogen, contradicting the belief that they share Earth's composition; Henry Norris Russell persuaded her to call it spurious, then confirmed it in 1929.

Which physicist won the 1967 Nobel Prize for explaining how stars generate energy?

Hans Bethe's 1939 paper 'Energy Production in Stars' worked out the proton-proton chain and the CNO cycle; he had left Nazi Germany in 1933 and later led the theory division at Los Alamos.

Who showed in 1859 that the Sun's dark spectral lines come from absorbing elements?

Gustav Kirchhoff, working with Robert Bunsen in Heidelberg, showed in 1859 that each dark Fraunhofer line matches a bright line emitted by a specific element, revealing sodium, iron and more in the Sun.

Who in 1666 passed sunlight through a prism to show it is made up of light of many colours?

Isaac Newton's prism split sunlight into its colours; more than a century later, in 1800, William Herschel found infrared lurking beyond the red end of the same spectrum.

The Homestake solar-neutrino experiment ran deep in a gold mine in which US state?

Raymond Davis Jr. ran the experiment 1,500 m down in the Homestake gold mine at Lead, South Dakota, finding only about a third of the predicted neutrinos; he shared the 2002 Nobel Prize.

Which Greek, c. 310–230 BC, proposed the first known Sun-centred model of the universe?

Aristarchus of Samos's own text is lost; we know his heliocentric model through Archimedes' The Sand Reckoner, and Copernicus cited him in a passage cut from De revolutionibus.

Which Greek philosopher called the Sun a flaming metal ball larger than the Peloponnese?

Anaxagoras held the Sun to be a red-hot mass larger than the Peloponnese and reasoned that the Moon shines by reflected sunlight; the claim got him charged with impiety in Athens.

Who first found a reasonably accurate Earth–Sun distance in 1672, via a Mars parallax?

Giovanni Cassini sent Jean Richer to Cayenne in French Guiana for simultaneous Mars observations in 1672, measured the parallax, then scaled up to the Sun using Kepler's laws — about 140 million km.

James Cook's 1769 voyage to observe a transit of Venus took him to which island?

James Cook's first voyage on HMS Endeavour reached Tahiti in April 1769 to time the 3 June transit of Venus from Point Venus, before sailing on to New Zealand and Australia.

Every second, the Sun converts roughly how much mass directly into energy?

Converting about 4.26 billion kg of mass per second — from fusing some 600 billion kg of hydrogen — yields 384.6 yottawatts, the equivalent of 92 billion megatons of TNT every second.

The Sun's core is roughly how dense compared with liquid water?

At 150 g/cm³ it is denser than any metal, yet it is still a gas-like plasma. The core temperature is close to 15.7 million kelvin.

The Sun's radius is roughly what fraction of the Earth–Sun distance?

The solar radius of 695,700 km is about 1/215 of the 149.6 million km astronomical unit, which is why the Sun spans only about half a degree of sky.

With an absolute magnitude of +4.83, the Sun outshines what share of Milky Way stars?

The Sun, absolute magnitude +4.83, outshines about 85% of Milky Way stars, because most of the galaxy's stars are dim red dwarfs far fainter than our 'average' star.

When the Sun swells into a red giant billions of years from now, which planet will it engulf first?

Mercury goes first and Venus very likely follows; Earth's fate is uncertain, with models putting its engulfment around 7.59 billion years from now if tidal drag shrinks its orbit.

Earth reaches perihelion, its closest point to the Sun, in which month?

Perihelion falls in early January, in the middle of Northern Hemisphere winter — proof that the seasons come from axial tilt, not distance; aphelion falls in early July.

In Norse myth, which wolf chases the sun goddess Sól across the sky and devours her at Ragnarök?

Sköll hunts the sun while his fellow wolf Hati chases her brother Máni, the Moon; Sól rides a horse-drawn wagon like the Bronze Age Trundholm sun chariot.

Which Roman emperor made the cult of the Unconquered Sun an official religion in AD 274?

Aurelian dedicated a new temple to Sol Invictus in Rome on 25 December 274 and created a college of priests, the pontifices Solis, to serve the god.