The Sun Has Grown Larger and Brighter Over Its Lifetime
The Sun Has Grown Larger and Brighter Over Its Lifetime
The Sun has grown larger and brighter since it became a stable star about 4.5 billion years ago. Since it settled onto the main sequence, its radius has increased by about 15%, while its luminosity has risen by roughly 40–50%. It will continue to brighten gradually, becoming about 10% more luminous over the next 1 billion years. In about 5 billion years, after core hydrogen is exhausted, the Sun will expand dramatically into a red giant, becoming vastly larger and far brighter than it is today.
The Sun Is Actually White, Not Yellow
The Sun Is Actually White, Not Yellow
Viewed above Earth's atmosphere, the Sun appears white because its visible light spans the full rainbow and blends together. From the ground, the disk can look yellow, orange, or red because Earth's atmosphere scatters and filters sunlight, especially when the Sun is low in the sky.
A Single Photon May Spend Up to 170,000 Years Trapped Inside the Sun
A Single Photon May Spend Up to 170,000 Years Trapped Inside the Sun
Energy born by fusion in the Sun's core does not fly straight out. The plasma is so dense that photons get absorbed and re-emitted in a random walk that can last from tens of thousands to over 100,000 years. After this astonishing inner journey, the photon then crosses 150 million km (93 million mi) and reaches Earth in just 8 minutes 20 seconds.
The Sun's Atmosphere Is Hundreds of Times Hotter Than Its Surface
The Sun's Atmosphere Is Hundreds of Times Hotter Than Its Surface
The Sun's visible surface, the photosphere, is about 5,500 °C (9,900 °F), while its outer corona typically reaches about 1–3 million °C (1.8–5.4 million °F). Explaining why the outer atmosphere is so much hotter than the surface is one of the major open problems in solar physics.
The Sun Converts About 4 Million Metric Tons of Matter Into Energy Every Second
The Sun Converts About 4 Million Metric Tons of Matter Into Energy Every Second
Through nuclear fusion in its core, the Sun turns roughly 4 million metric tons (about 4.4 million U.S. tons) of mass directly into energy each second — Einstein's E=mc² in action. Including the solar wind, total mass loss climbs to about 5.5 million metric tons per second.
Helium Was Discovered on the Sun Before It Was Found on Earth
Helium Was Discovered on the Sun Before It Was Found on Earth
In 1868, French astronomer Pierre Janssen spotted a mysterious yellow line in the Sun's spectrum during a total eclipse over India. English astronomer Norman Lockyer saw the same line later that year and named the new element helium, after Helios, the Greek god of the Sun. Helium remained an "alien element" for 27 years until chemist William Ramsay isolated it on Earth in 1895.
Total Solar Eclipses Happen Because of a Stunning Cosmic Coincidence
Total Solar Eclipses Happen Because of a Stunning Cosmic Coincidence
The Sun is about 400 times wider than the Moon, and it is also about 400 times farther from Earth. That near-match in apparent size lets the Moon cover the Sun's bright disk during a total solar eclipse, briefly revealing the faint corona.
The Sun Holds About 99.86% of the Solar System's Mass
The Sun Holds About 99.86% of the Solar System's Mass
Nearly all the mass in the solar system belongs to the Sun. The planets, moons, asteroids, comets, and dust together account for only about 0.14%, with Jupiter holding most of that small remainder.
About 1.3 Million Earths Would Fit Inside the Sun
About 1.3 Million Earths Would Fit Inside the Sun
The Sun is about 109 Earths wide — but volume scales as the cube of size, so its interior could swallow roughly 1.3 million Earths. Despite this, the Sun is just an average-sized star; some giants are 1,000 times wider, and some red dwarfs are 10 times smaller.
The Sun Is Among the Roundest Natural Objects Ever Measured
The Sun Is Among the Roundest Natural Objects Ever Measured
Despite rotating and being made of plasma, the Sun is extraordinarily close to a perfect sphere. Its equatorial and polar diameters differ by only about 10 km (6 mi) across a diameter of roughly 1.39 million km (864,000 mi).
The Sun's Magnetic Poles Flip Every 11 Years
The Sun's Magnetic Poles Flip Every 11 Years
About every 11 years, near the peak of the solar cycle, the Sun's north and south magnetic poles swap places. The full magnetic cycle — flipping and flipping back — takes about 22 years. Earth's magnetic poles, by comparison, only flip every few hundred thousand years.
The 1859 Carrington Event Triggered Telegraph Chaos
The 1859 Carrington Event Triggered Telegraph Chaos
The Carrington Event of September 1859 was the most intense geomagnetic storm in recorded history. Auroras were seen far from the poles, telegraph systems malfunctioned, operators reported shocks, and some equipment sparked or ignited paper.
The Sun's Core Is About 13 Times Denser Than Solid Lead
The Sun's Core Is About 13 Times Denser Than Solid Lead
At the Sun's center, plasma is squeezed to about 150 g/cm³ — roughly 13 times the density of lead and about 150 times denser than water. A thumb-sized piece would weigh nearly as much as a six-pack of soda. Yet because it's plasma rather than solid, it still flows.
The Sun's Core Reaches About 15 Million °C (27 Million °F)
The Sun's Core Reaches About 15 Million °C (27 Million °F)
Temperatures at the Sun's center top 15 million °C (27 million °F) — about 2,500 times hotter than its surface and hot enough to crush hydrogen atoms together until they fuse into helium. This furnace powers everything we call sunshine.
Parker Solar Probe Is the Fastest Human-Made Object Ever
Parker Solar Probe Is the Fastest Human-Made Object Ever
On December 24, 2024, NASA's Parker Solar Probe screamed past the Sun at 692,000 km/h (430,000 mph), or about 0.064% the speed of light. That's fast enough to fly from Philadelphia to Washington, D.C. in one second.
Parker Solar Probe Has Flown Through the Sun's Atmosphere Without Melting
Parker Solar Probe Has Flown Through the Sun's Atmosphere Without Melting
During its closest passes, NASA's Parker Solar Probe travels through the corona, the Sun's outer atmosphere. Its carbon-composite heat shield can face temperatures of about 980 °C (1,800 °F) while keeping the spacecraft's instruments within safe operating conditions.
The Sun Is Racing Around the Milky Way at About 720,000 km/h
The Sun Is Racing Around the Milky Way at About 720,000 km/h
The Sun, carrying the entire solar system with it, moves around the Milky Way's center at about 720,000 km/h (450,000 mph). Even at that speed, one full orbit of the galaxy takes roughly 230 million years.
The Sun Has Made Only About 20 Trips Around the Galaxy
The Sun Has Made Only About 20 Trips Around the Galaxy
In its 4.6 billion years of existence, the Sun has completed only about 20 full orbits around the Milky Way's center. The last time the Sun was in roughly its current position, the dinosaurs were just emerging on Earth.
The Sun's Core Produces Surprisingly Little Power Per Cubic Meter
The Sun's Core Produces Surprisingly Little Power Per Cubic Meter
Fusion in the Sun's core is immensely important, but it is spread through a vast region. The core's average power density is only on the order of a few hundred watts per cubic meter, far lower than many people imagine for a star.
The Sun Will Swallow Mercury and Venus — and Earth's Fate Is Uncertain
The Sun Will Swallow Mercury and Venus — and Earth's Fate Is Uncertain
In about 5 billion years, the Sun will leave its stable hydrogen-burning phase and expand into a red giant. Mercury and Venus are expected to be engulfed; Earth's ultimate fate is still modeled with uncertainty, though it will become uninhabitable much earlier.
The Sun Is Slowly Growing Brighter
The Sun Is Slowly Growing Brighter
As hydrogen turns into helium in its core, the Sun gradually becomes more luminous over enormous timescales. Standard models indicate its brightness increases by about 10% per billion years, a slow change with major consequences for Earth's far future.
The Sun Is Plasma, Not Gas
The Sun Is Plasma, Not Gas
The Sun is so hot that most of its hydrogen and helium atoms have been stripped of their electrons. The result isn't gas but plasma — a fourth state of matter where positively charged ions and free electrons move independently. Plasma is what lets the Sun generate its tangled, ever-changing magnetic fields.
The Sun's Surface Gravity Is About 28 Times Earth's
The Sun's Surface Gravity Is About 28 Times Earth's
The Sun's surface gravity is about 274 m/s², compared with Earth's 9.8 m/s². A 70 kg (154 lb) person would experience a weight force about 28 times larger there, if standing on the Sun were possible.
Escaping the Sun's Surface Would Require 618 km/s (384 mi/s)
Escaping the Sun's Surface Would Require 618 km/s (384 mi/s)
The Sun's escape velocity is more than 55 times Earth's. That extreme threshold is why it has held onto its mass for billions of years despite blasting out the solar wind in every direction.
The Sun Has No Solid Surface
The Sun Has No Solid Surface
If you could fly into the Sun, you would never crash into anything solid. The "surface" we see — the photosphere — is simply the layer where the Sun's plasma becomes transparent enough for light to escape. Inside, it is just hotter and denser plasma all the way down.
Our Whole Solar System Sits Inside a Giant Solar Bubble
Our Whole Solar System Sits Inside a Giant Solar Bubble
The Sun's magnetic field, carried outward by the solar wind, creates a giant bubble called the heliosphere. Voyager 1 didn't cross its boundary into true interstellar space until 2012, at a distance of about 121 AU — more than 18 billion km (11 billion mi) from the Sun.
10 Million Plasma Jets Erupt From the Sun at Any Moment
10 Million Plasma Jets Erupt From the Sun at Any Moment
NASA reports that at any given moment, about 10 million slender plasma jets called spicules are erupting from the Sun's chromosphere. Each shoots up at about 97 km/s (60 mi/s) and reaches 9,700 km (6,000 mi) before collapsing. Together they look like a forest of grass covering the Sun.
A Coronal Mass Ejection Can Hurl Billions of Tons of Plasma at 11 Million km/h
A Coronal Mass Ejection Can Hurl Billions of Tons of Plasma at 11 Million km/h
The most violent solar storms — coronal mass ejections — can fling billions of metric tons (billions of U.S. tons) of plasma into space. Typical CMEs cross to Earth in 1–3 days, but the fastest can reach us in under a day, traveling at speeds of up to 11 million km/h (7 million mph).
A Powerful X-Class Solar Flare Can Release the Energy of About a Billion Hydrogen Bombs
A Powerful X-Class Solar Flare Can Release the Energy of About a Billion Hydrogen Bombs
NASA has compared the energy of a major solar flare to about a billion hydrogen bombs. Flares erupt when stored magnetic energy in the Sun's atmosphere is released rapidly across many wavelengths of light.
The Sun Was 30% Dimmer When Earth Formed
The Sun Was 30% Dimmer When Earth Formed
When Earth formed 4.5 billion years ago, the young Sun shone only about 70% as brightly as today. By rights, Earth's oceans should have been frozen solid for the first 2 billion years — yet they were not. This unresolved "faint young Sun paradox" is still actively debated.
Sunlight Takes 8 Minutes 20 Seconds to Reach Earth
Sunlight Takes 8 Minutes 20 Seconds to Reach Earth
Light moves at about 300,000 km/s (186,000 mi/s), yet it still needs about 8 minutes 20 seconds to cross the 150 million km (93 million mi) from Sun to Earth. We always see the Sun as it was 8 minutes ago — if it vanished right now, we would not know for over 8 minutes.
The Sun Is About 4.6 Billion Years Old
The Sun Is About 4.6 Billion Years Old
The Sun formed about 4.6 billion years ago when a giant cloud of gas and dust — the solar nebula — collapsed under its own gravity. The hydrogen and most of the helium in the Sun were forged in the Big Bang itself; the heavier elements were cooked in earlier generations of stars and ejected by supernovae.
The Sun's Core Appears to Rotate Faster Than Its Surface
The Sun's Core Appears to Rotate Faster Than Its Surface
Measurements from the SOHO spacecraft indicate that the Sun's core may rotate about four times faster than the visible surface. Scientists interpret this as a possible remnant of the young Sun's earlier rotation history.
The Sun Spins Faster at Its Equator Than at Its Poles
The Sun Spins Faster at Its Equator Than at Its Poles
Because the Sun is plasma rather than solid, different latitudes can rotate at different speeds. The equator completes one rotation every 25 days, while the poles take about 36 days — a phenomenon called differential rotation. This shearing motion is what tangles the Sun's magnetic field and drives sunspots and flares.
The Young Sun Likely Spun Much Faster Than It Does Today
The Young Sun Likely Spun Much Faster Than It Does Today
Like many young stars, the early Sun probably rotated several times faster than it does now. Over billions of years, the solar wind carried away angular momentum and gradually slowed the star's spin.
Cecilia Payne Showed That the Sun Is Mostly Hydrogen
Cecilia Payne Showed That the Sun Is Mostly Hydrogen
In 1925, Cecilia Payne-Gaposchkin demonstrated that stars, including the Sun, are made mainly of hydrogen and helium. Her conclusion overturned the prevailing assumption that stars had compositions similar to Earth and became a foundation of modern astrophysics.
The Sun's Closest Stellar Neighbor Is 4.24 Light-Years Away
The Sun's Closest Stellar Neighbor Is 4.24 Light-Years Away
That neighbor is Proxima Centauri, a faint red dwarf in the Alpha Centauri system. A light-year is about 9.46 trillion km (5.88 trillion mi). Even Voyager 1, the farthest human-made object, would take over 70,000 years to reach it at its current speed.
The Sun Will Eventually Become a White Dwarf About the Size of Earth
The Sun Will Eventually Become a White Dwarf About the Size of Earth
After the red-giant phase, the Sun will shed its outer layers and leave behind a hot, compact white dwarf. That remnant will be roughly Earth-sized while containing a large fraction of the Sun's current mass.
The Sun Will Not Explode as a Supernova
The Sun Will Not Explode as a Supernova
The Sun is not massive enough for a core-collapse supernova. Its later life will be comparatively gentle: red giant, ejected outer layers forming a glowing planetary nebula, then a slowly cooling white dwarf left behind for trillions of years.
No Black Dwarf Exists Anywhere in the Universe Yet
No Black Dwarf Exists Anywhere in the Universe Yet
A white dwarf cools so slowly that the theoretical "black dwarf" — a fully cooled, non-radiating stellar remnant — takes far longer than the current age of the universe to form. None has ever existed in 13.8 billion years of cosmic history.
The Sun's Core Pressure Is About 250 Billion Times Earth's Atmosphere
The Sun's Core Pressure Is About 250 Billion Times Earth's Atmosphere
At the Sun's center, pressure reaches roughly 26.5 million gigapascals (about 250 billion atm). This crushing weight is what allows nuclear fusion to happen at temperatures that would otherwise be far too cool to ignite hydrogen.
The Sun's Main Fusion Process Turns Hydrogen Into Helium
The Sun's Main Fusion Process Turns Hydrogen Into Helium
Most of the Sun's energy comes from the proton–proton chain, a series of nuclear reactions in which hydrogen nuclei ultimately combine to form helium. A small fraction of the original mass becomes energy.
Trillions of Solar Neutrinos Pass Through You Every Second
Trillions of Solar Neutrinos Pass Through You Every Second
NASA describes enormous numbers of neutrinos streaming from the Sun's core straight through everything in their path — including your body — because they almost never interact with matter. About 65 billion solar neutrinos cross every square centimeter of you each second.
A 1919 Solar Eclipse Made Einstein's Gravity Famous
A 1919 Solar Eclipse Made Einstein's Gravity Famous
During the total solar eclipse of May 29, 1919, astronomers measured the apparent shift of background stars near the Sun. The result was widely reported as support for Einstein's general theory of relativity and made him internationally famous.
Many Civilizations Honored the Sun as a Divine Power
Many Civilizations Honored the Sun as a Divine Power
Sun deities and solar symbolism appear in cultures across the world, including Ra in ancient Egypt, Helios in Greece, Surya in India, Inti among the Inca, and Amaterasu in Japan. The Sun's daily return made it a natural symbol of power, order, and renewal.
The Sun Has a Vast Tail in Interstellar Space
The Sun Has a Vast Tail in Interstellar Space
As the solar system moves through the local interstellar medium, the heliosphere is shaped into an extended structure with a downstream region often called the heliotail. NASA's IBEX mission mapped evidence of this distant tail.
The 2027 Total Solar Eclipse Will Be Exceptionally Long
The 2027 Total Solar Eclipse Will Be Exceptionally Long
The total solar eclipse of August 2, 2027, will reach a maximum totality of about 6 minutes 23 seconds near Luxor, Egypt. It will be one of the longest total solar eclipses visible from land in the modern era.
A Total Solar Eclipse Can Last at Most About 7.5 Minutes
A Total Solar Eclipse Can Last at Most About 7.5 Minutes
At any single point on Earth, the totality phase of a solar eclipse can last no longer than about 7 minutes 32 seconds. The Moon's shadow sweeps across Earth's surface at over 1,700 km/h (1,000 mph), so totality is always fleeting.
The Sun's Light Is About 400,000 Times Brighter Than a Full Moon
The Sun's Light Is About 400,000 Times Brighter Than a Full Moon
The Sun's apparent magnitude is −26.74, compared with the full Moon's −12.74. The scale is logarithmic, so even that small numerical gap translates to the Sun delivering about 400,000 times more light to your eye than the Moon does.
Sunspots Look Dark Only Because They're Cooler Than Their Surroundings
Sunspots Look Dark Only Because They're Cooler Than Their Surroundings
Sunspots are about 3,500–4,500 °C (6,300–8,100 °F) — still scorching, but cooler than the surrounding 5,500 °C (9,900 °F) photosphere. They look black only by comparison. Plucked out and placed alone in the sky, a sunspot would shine brighter than a full Moon.
The Largest Sunspot Groups Can Be Bigger Than Jupiter
The Largest Sunspot Groups Can Be Bigger Than Jupiter
Individual sunspots vary widely in size, and enormous sunspot groups can stretch beyond 160,000 km (100,000 mi) across — larger than Jupiter's diameter. The largest groups are among the most dramatic visible signs of solar magnetism.
The Sun Destroys Many Sungrazing Comets
The Sun Destroys Many Sungrazing Comets
Some comets plunge so close to the Sun that they evaporate or break apart. The SOHO spacecraft has discovered more than 5,000 comets, many of them sungrazers seen on their final approach.
The Sun Is Mostly Hydrogen and Helium
The Sun Is Mostly Hydrogen and Helium
By mass, the Sun is about 73% hydrogen, 25% helium, and 2% everything else (oxygen, carbon, neon, iron, and other heavier elements). By count of atoms, hydrogen dominates even more — about 91% of all atoms in the Sun are hydrogen.
Earth Is Closest to the Sun in January, Not Summer
Earth Is Closest to the Sun in January, Not Summer
Earth's orbit is not a perfect circle. Earth is closest to the Sun (perihelion) in early January at about 147 million km (91.4 million mi), and farthest (aphelion) in early July at 152 million km (94.5 million mi). Seasons are caused by Earth's axial tilt, not by these distance changes.
Sunspots Were First Seen Through a Telescope in 1610
Sunspots Were First Seen Through a Telescope in 1610
Galileo Galilei and several contemporaries observed sunspots in 1610–1611, shattering the medieval idea that the Sun was perfect and unchanging. Galileo used safe projection techniques to avoid blinding himself.
The Maunder Minimum Was a Long Spell of Very Few Sunspots
The Maunder Minimum Was a Long Spell of Very Few Sunspots
From about 1645 to 1715, telescopic observers recorded unusually few sunspots, a period now called the Maunder Minimum. It overlapped with part of the Little Ice Age, but the strength and nature of any climate connection remain debated.
Earth Travels Around the Sun at About 107,000 km/h
Earth Travels Around the Sun at About 107,000 km/h
Earth's orbital speed averages about 107,000 km/h (67,000 mph). At that rate, our planet sweeps through more than 940 million km (584 million mi) of space every year, even while we feel completely still.
The Sun Is Classified as a G2V Main-Sequence Star
The Sun Is Classified as a G2V Main-Sequence Star
Astronomers classify the Sun as a G2V star. 'G2' describes its temperature and spectral properties, while 'V' indicates that it is a main-sequence star fusing hydrogen in its core.
The Sun Is Brighter Than Most Stars in the Milky Way
The Sun Is Brighter Than Most Stars in the Milky Way
Most stars in the Milky Way are small, faint red dwarfs. The Sun is not an unusually massive star, but it is more luminous than the large majority of stars in our galaxy.
A White Dwarf Sun Will Shine From Stored Heat, Not Fusion
A White Dwarf Sun Will Shine From Stored Heat, Not Fusion
When the Sun becomes a white dwarf, nuclear fusion will have ended. The remnant will glow because of leftover heat and then cool very slowly over immense spans of time.
Earth Intercepts Only a Tiny Fraction of the Sun's Power
Earth Intercepts Only a Tiny Fraction of the Sun's Power
The Sun radiates energy in every direction, and Earth catches only about one two-billionth of that total output. That tiny share is still enough to power our planet's climate and nearly all life at the surface.
The Sun Radiates About 3.8 × 10²⁶ Watts
The Sun Radiates About 3.8 × 10²⁶ Watts
The Sun's luminosity is about 3.8 × 10²⁶ watts. That equals roughly 3.8 trillion trillion 100-watt lightbulbs shining at once.
The Solar Wind Begins as Coronal Plasma Escaping Into Space
The Solar Wind Begins as Coronal Plasma Escaping Into Space
The Sun's hot outer atmosphere continually expands outward as charged particles. Once that escaping coronal plasma streams through interplanetary space, it is known as the solar wind.
Fast Solar Wind Can Reach 800 km/s
Fast Solar Wind Can Reach 800 km/s
Solar wind from coronal holes can approach 800 km/s (about 2.9 million km/h or 1.8 million mph). Slower solar wind from quieter regions drifts at 300–500 km/s. Both blend into the spiral pattern of charged particles that bathes Earth.
Solar Wind Takes 2–4 Days to Reach Earth
Solar Wind Takes 2–4 Days to Reach Earth
The solar wind crosses the 150 million km (93 million mi) from Sun to Earth in roughly 2 to 4 days, depending on its speed. When it arrives, it creates auroras and can disturb satellites and power grids.
Auroras Are Powered by Particles From the Sun
Auroras Are Powered by Particles From the Sun
The northern and southern lights appear when charged particles guided by Earth's magnetic field collide with gases high in the atmosphere. Oxygen and nitrogen emit characteristic colors that produce the glowing curtains and arcs.
The Sun's Diameter Is About 1.39 Million km (864,000 mi)
The Sun's Diameter Is About 1.39 Million km (864,000 mi)
The Sun's diameter is roughly 1.39 million km (864,000 mi) — about 109 times Earth's diameter and about 10 times Jupiter's. Shrunk to the size of a basketball, Earth would be smaller than the head of a pin.
The Sun's Mass Is About 333,000 Times Earth's
The Sun's Mass Is About 333,000 Times Earth's
The Sun's mass is about 1.989 × 10³⁰ kg, or roughly 2 nonillion U.S. tons. Despite losing 4 million metric tons per second to fusion, the Sun is so vast that this loss is rounding error over billions of years.
The Sun's Average Density Is Lower Than Earth's
The Sun's Average Density Is Lower Than Earth's
Although the Sun's core is enormously compressed, its overall average density is about 1,408 kg/m³ — only about 1.4 times that of water, and roughly one quarter of Earth's mean density.
One Astronomical Unit Equals the Average Earth–Sun Distance
One Astronomical Unit Equals the Average Earth–Sun Distance
That average is about 149.6 million km (93 million mi), defined as 1 astronomical unit (AU). Astronomers use the AU as a standard measuring stick throughout the solar system, from Mercury's orbit (0.39 AU) to Neptune's (30 AU).
The Sun Sings — But We Cannot Hear It
The Sun Sings — But We Cannot Hear It
Pressure waves bouncing through the Sun's interior cause it to ring like a bell. Scientists use a technique called helioseismology to "see" inside the Sun by measuring these oscillations. The waves vibrate at frequencies far too low for human ears to detect.
The Sun's Surface Pulses in Roughly Five-Minute Rhythms
The Sun's Surface Pulses in Roughly Five-Minute Rhythms
Patches of the solar surface rise and fall with typical periods of about five minutes. These oscillations are caused by sound waves trapped inside the Sun and are central to the science of helioseismology.
The Solar System Contains Faint Dust Rings Around the Sun
The Solar System Contains Faint Dust Rings Around the Sun
NASA has identified tenuous dust structures in the inner solar system. These rings and bands are shaped by planetary gravity and by the leftover debris that still drifts around the Sun.
The Sun's Surface Bubbles Like a Boiling Pot
The Sun's Surface Bubbles Like a Boiling Pot
Up close, the photosphere is mottled with granules — each one a roiling convection cell about 1,000 km (620 mi) across. Hot plasma rises in the center, cools, and sinks back down in cooler dark lanes. Each granule lasts only 8–20 minutes before being replaced.
The Sun Has Giant Convection Flow Cells About 200,000 km Wide
The Sun Has Giant Convection Flow Cells About 200,000 km Wide
Above the small everyday granules, NASA has detected enormous circulation patterns roughly 200,000 km (124,000 mi) across. These giant cells help move heat from deep inside the Sun toward the surface.
Nearly All of the Sun's Energy Comes From Its Inner Core
Nearly All of the Sun's Energy Comes From Its Inner Core
Hydrogen fusion is concentrated in the Sun's central region. Roughly 99% of the Sun's energy is generated within about the inner quarter of its radius, where temperature and pressure are high enough for fusion to proceed efficiently.
Scientists Describe the Sun in Several Major Layers
Scientists Describe the Sun in Several Major Layers
Solar scientists commonly describe the Sun using interior and atmospheric regions such as the core, radiative zone, tachocline, convection zone, photosphere, chromosphere, transition region, and corona. Each region behaves differently.
The Sun's Magnetic Field Spirals Through Space
The Sun's Magnetic Field Spirals Through Space
As the Sun rotates while the solar wind flows outward, its magnetic field twists into a giant "Parker spiral" that fills the entire solar system. The pattern was predicted in 1958 by physicist Eugene Parker, who later became the namesake of NASA's Parker Solar Probe.
Solar Prominences Can Last for Months
Solar Prominences Can Last for Months
Loop-shaped arcs of plasma anchored to the Sun by magnetic field lines, prominences can extend hundreds of thousands of kilometers above the surface — more than 30 Earths could fit inside a big one. Stable ones can hover for weeks or even months.
A Prominence Seen Against the Sun's Face Is Called a Filament
A Prominence Seen Against the Sun's Face Is Called a Filament
The same plasma structure appears bright when seen at the Sun's edge (because it glows against dark space) and dark when silhouetted against the Sun's far brighter disk. Filaments and prominences are physically identical — only the viewing angle changes.
Plasma Can Fall Back Toward the Sun Like Rain
Plasma Can Fall Back Toward the Sun Like Rain
After certain solar eruptions, hot coronal plasma can cool, condense, and stream downward along magnetic field lines. NASA calls this dazzling phenomenon "coronal rain" — and it looks just as the name suggests.
Coronal Holes Are Dark "Doors" Where Solar Wind Pours Out
Coronal Holes Are Dark "Doors" Where Solar Wind Pours Out
These cooler, less dense regions in extreme-ultraviolet images have open magnetic field lines stretching into space. They release the fastest streams of solar wind, sometimes triggering geomagnetic storms when they face Earth.
A Tiny Layer May Drive the Sun's Magnetic Engine
A Tiny Layer May Drive the Sun's Magnetic Engine
The tachocline, a thin region near the boundary between the radiative zone and the convection zone, is thought to be where the solar dynamo generates the Sun's large-scale magnetic field — the engine behind every sunspot and flare.
The Sun Can Produce Quakes of Its Own
The Sun Can Produce Quakes of Its Own
Powerful solar flares can trigger sunquakes — rippling seismic waves that spread across the Sun's surface like ripples on a pond. NASA has observed these flare-linked disturbances and continues to study how they're generated.
Parker Solar Probe Became the First Spacecraft to Fly Through the Corona
Parker Solar Probe Became the First Spacecraft to Fly Through the Corona
In 2021, NASA announced that Parker Solar Probe had crossed into the corona, the Sun's outer atmosphere. That milestone made it the first spacecraft to sample that region directly.
Solar Flares Are Among the Most Powerful Explosions in the Solar System
Solar Flares Are Among the Most Powerful Explosions in the Solar System
A solar flare is a sudden burst of energy from the Sun's atmosphere, emitted across radio, visible, ultraviolet, and X-ray wavelengths. The strongest flares release extraordinary amounts of energy in only minutes.
Solar Flares and Coronal Mass Ejections Are Not the Same Thing
Solar Flares and Coronal Mass Ejections Are Not the Same Thing
Flares are intense bursts of electromagnetic radiation that travel at the speed of light. CMEs are giant clouds of magnetized plasma that take hours to days to reach Earth. They often happen together, but they are distinct phenomena.
A Flare's Radiation Reaches Earth in 8 Minutes; the CME Takes Days
A Flare's Radiation Reaches Earth in 8 Minutes; the CME Takes Days
The X-rays and ultraviolet light from a solar flare cross from Sun to Earth at the speed of light. The plasma cloud of an accompanying CME usually takes 1–3 days to arrive, giving forecasters precious time to warn satellites and grid operators.
A Solar Flare Once Made Earth's Atmosphere Pulse in Step With It
A Solar Flare Once Made Earth's Atmosphere Pulse in Step With It
NASA researchers found that pulses in Earth's upper atmosphere mirrored X-ray oscillations during a solar flare on July 24, 2016 — showing how solar eruptions can ripple through near-Earth space in real time.
The Sun's Magnetism Is Mild on Average but Extreme in Sunspots
The Sun's Magnetism Is Mild on Average but Extreme in Sunspots
The Sun's large-scale surface magnetic field is relatively weak overall, but active regions can become enormously stronger. Inside sunspots, magnetic fields can reach thousands of gauss.
Solar Orbiter Delivered the First Direct Views of the Sun's South Pole
Solar Orbiter Delivered the First Direct Views of the Sun's South Pole
In 2025, ESA and NASA released the first direct images of the Sun's south polar region from Solar Orbiter. Observing the poles is important because they are difficult to see from Earth's near-equatorial viewpoint.
The Sun's South Pole Looked Magnetically Mixed During Solar Maximum
The Sun's South Pole Looked Magnetically Mixed During Solar Maximum
Solar Orbiter detected mixed magnetic polarities near the Sun's south pole during the active phase of the solar cycle. Such tangled polar fields are expected around the period when the Sun's global magnetic polarity reverses.
Solar Cycle 25 Entered Its Maximum Phase in 2024
Solar Cycle 25 Entered Its Maximum Phase in 2024
NASA and NOAA announced in October 2024 that Solar Cycle 25 had reached its solar maximum period. During this active phase, sunspots, flares, and coronal mass ejections become more frequent.
The Solar Cycle Was First Discovered in 1843
The Solar Cycle Was First Discovered in 1843
German astronomer Heinrich Schwabe discovered the 11-year sunspot cycle by patiently counting sunspots for 17 years, hoping to find a planet inside Mercury's orbit. He found a cycle of solar activity instead.
People Have Recorded Sunspots for More Than 2,000 Years
People Have Recorded Sunspots for More Than 2,000 Years
Historical records from East Asia describe naked-eye sunspots long before telescopes existed. Systematic telescopic sunspot observations began in the early 1600s.
The Wolf Number Counts Sunspots
The Wolf Number Counts Sunspots
In 1848, Swiss astronomer Rudolf Wolf devised a formula for counting sunspots that still bears his name — the Wolf number, sometimes called the international sunspot number. It remains the standard tool for tracking the solar cycle.
Aristarchus Proposed a Sun-Centered Cosmos in the 3rd Century BC
Aristarchus Proposed a Sun-Centered Cosmos in the 3rd Century BC
Aristarchus of Samos argued that Earth moves around the Sun, centuries before the heliocentric model became accepted in early modern astronomy.
Anaxagoras Said the Sun Was a Fiery Physical Object
Anaxagoras Said the Sun Was a Fiery Physical Object
In 5th-century BC Greece, Anaxagoras argued that the Sun was a blazing physical body rather than a deity. Ancient accounts say his naturalistic ideas contributed to accusations of impiety.
Eratosthenes Used Sun Shadows to Estimate Earth's Size
Eratosthenes Used Sun Shadows to Estimate Earth's Size
Around the 3rd century BC, Eratosthenes compared noon Sun angles at two locations in Egypt to estimate Earth's circumference. His result was remarkably close to the modern value.
Fraunhofer Mapped Hundreds of Dark Lines in Sunlight
Fraunhofer Mapped Hundreds of Dark Lines in Sunlight
In the early 19th century, Joseph von Fraunhofer cataloged hundreds of dark absorption lines in the Sun's spectrum. Those lines later became essential evidence for identifying the Sun's chemical composition.
The First Photograph of the Sun Was Taken in 1845
The First Photograph of the Sun Was Taken in 1845
French physicists Louis Fizeau and Léon Foucault captured the first photograph of the Sun on April 2, 1845, using an early daguerreotype. The image clearly showed sunspots on the solar disk.
The Sun's Light Carries Enough Force to Sail On
The Sun's Light Carries Enough Force to Sail On
Photons carry momentum, and pressure from sunlight can be harnessed to push lightweight spacecraft. The Planetary Society's LightSail 2 mission demonstrated this propellantless propulsion in Earth orbit in 2019.
Sunlight Can Support Ocean Photosynthesis Down to About 200 m
Sunlight Can Support Ocean Photosynthesis Down to About 200 m
In clear ocean water, enough sunlight may penetrate to roughly 200 m (656 ft) for photosynthesis. This upper layer is called the photic zone.
Sunlight Powers Almost All Life on Earth
Sunlight Powers Almost All Life on Earth
Almost every food chain on Earth traces back to plants that capture sunlight through photosynthesis. The only major exceptions are deep-sea hydrothermal-vent ecosystems that rely on chemical energy from the planet's interior.
Without Sunlight, Earth's Surface Would Cool Rapidly
Without Sunlight, Earth's Surface Would Cool Rapidly
If solar heating vanished, Earth's surface would fall below freezing within about a week and continue cooling afterward. The atmosphere and oceans would retain heat longer than land, so the planet would not become a solid ice ball within days.
Sunlight Drives Earth's Entire Weather System
Sunlight Drives Earth's Entire Weather System
Every storm, hurricane, wind, and ocean current on Earth is ultimately powered by uneven heating from the Sun. Air rises where the Sun warms it most (near the equator) and sinks where it cools (near the poles), creating the global circulation behind our weather.
Sunlight Helps the Body Make Vitamin D
Sunlight Helps the Body Make Vitamin D
Ultraviolet B radiation from sunlight triggers vitamin D production in skin. How much vitamin D a person makes depends on factors such as season, latitude, skin pigmentation, age, clothing, and sunscreen use.
The Sun's Ultraviolet Rays Can Damage Skin
The Sun's Ultraviolet Rays Can Damage Skin
UVA and UVB radiation from the Sun can damage skin cells and raise the risk of sunburn, premature aging, and skin cancer. Earth's ozone layer blocks most UVC radiation before it reaches the ground.
A Tan Is a Sign of UV Injury, Not a Safe Shield
A Tan Is a Sign of UV Injury, Not a Safe Shield
Skin darkens after ultraviolet exposure because the body increases melanin production in response to damage. Public-health agencies emphasize that a tan does not mean skin is unharmed.
Daylight Helps Regulate the Human Body Clock
Daylight Helps Regulate the Human Body Clock
Bright morning light helps align circadian rhythms by signaling the brain that daytime has begun. Light exposure influences sleep timing and wakefulness.
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