The Sun

The Sun is the closest star to Earth and is the center of our solar system. A giant, spinning ball of very hot gas, the Sun is fueled by nuclear fusion reactions. The light from the Sun heats our planet and makes life possible. The Sun is also an active star that displays sunspots, solar flares, erupting prominences, and coronal mass ejections. These phenomena, which are all related to the Sun's magnetic field, impact our near-Earth space environment and determine our "space weather". In about five billion years, the Sun will evolve into a Red Giant, and eventually, a White Dwarf star. Many cultures have had interesting myths about the Sun, in recognition of its importance to life on Earth.
The outermost layer of the <a href="/sun/solar_atmosphere.html">Sun's atmosphere</a> is the <a href="/sun/atmosphere/corona.html">corona</a>. The corona is very, very hot - about 1 million degrees! Glowing <a href="/sun/Solar_interior/Sun_layers/Core/plasma_state.html">plasma</a>, which is like magnetized gas, sometimes forms loops in the corona. <a href="/sun/atmosphere/sunspot_magnetism.html">Magnetic fields around sunspots</a> make these loops, called coronal loops. The loops are huge - about 30 Earths would fit across them! A satellite named TRACE took this picture in November 1999.<p><small><em>Image courtesy of NASA/Trace Mission</em></small></p>The "surface" of the Sun (the <a href="/sun/atmosphere/photosphere.html">photosphere</a>) is covered with a "granulation pattern" caused by the convective flow of heat rising to the photosphere from the <a href="http://www.windows2universe.org/sun/solar_interior_new.html">Sun's interior</a>. The granulation pattern is similar to what you see when you look at the top of a pot of boiling oatmeal. Note how the hotter centers of granules bulge upward, while the cooler edges are sinking downward.<p><small><em> Image courtesy of Goran Scharmer and Mats G. Lfdahl of the Royal Swedish Academy of Sciences</em></small></p>Astronomers use different wavelengths of light and other <a href="/physical_science/magnetism/em_radiation.html">electromagnetic emissions</a> as <a href="/sun/spectrum/multispectral_sun.html">"windows" into different regions of the Sun</a>. White light with a <a href="/physical_science/basic_tools/wavelength.html">wavelength</a> between 400 and 700 nanometers (nm) shows the <a href="/sun/atmosphere/photosphere.html">photosphere</a>, the visible "surface" of the Sun. Other wavelengths highlight different features of the Sun, such as its <a href="/sun/sun_magnetic_field.html">magnetic field</a>, the <a href="/sun/atmosphere/chromosphere.html">chromosphere</a> and the <a href="http://www.windows2universe.org/sun/atmosphere/corona.html">corona</a>.<p><small><em>Composite image courtesy of Windows to the Universe using images from SOHO (NASA and ESA), NCAR/HAO/MLSO, Big Bear Solar Observatory, and SDO/AIA.</em></small></p>On 21 April, 2010, the Solar Dynamics Observatory captured the launch of a filament from the <a href="/sun/atmosphere/photosphere.html">surface of the Sun</a>. These are the most detailed images of the Sun ever taken. The images show light in the <a href="/physical_science/magnetism/em_ultraviolet.html">ultraviolet</a> part of the <a href="/physical_science/magnetism/em_spectrum.html">electromagnetic spectrum</a>. The Sun is now entering another period of <a href="/sun/solar_activity.html">solar activity</a> after several years of a relatively quiet Sun. Activity on the Sun varies on an <a href="/sun/activity/sunspot_cycle.html">cycle of about 11 years</a>.<p><small><em>Image courtesy of NASA/Solar Dynamics Observatory and AIA Consortium</em></small></p>Sunspots don't look that big when you see them on the Sun (remember NEVER look directly at the Sun), but in fact they can be enormous! This composite image shows just how big sunspots can be, to scale with an image of Earth. Sunspots can be as big, or bigger, than Earth. The <a href="/sun/activity/sunspot_history.html">earliest written record of a sunspot observation</a> was made by Chinese astronomers around 800 B.C.<p><small><em>Image courtesy of Windows to the Universe using images from the Royal Swedish Academy of Sciences (sunspot image) and NASA (Earth image).</em></small></p>For the Aztecs, who lived in central Mexico, <a href="/mythology/tonatiuh.html">Tonatiuh</a> was a <a href="/sun/sun.html">Sun</a> god. Aztecs believed that four suns had been created in four previous ages, and all of them had died at the end of each cosmic era. Tonatiuh was the fifth sun and the present era is still his. The carvings on this sunstone represent the four cycles of creation and destruction in the Aztec creation story. The skull at the center depicts the god Tonatiuh.<p><small><em> Image courtesy of Corel Corporation.</em></small></p>

Explore The Sun

Interior

To understand how our Sun works, it helps to imagine that the inside of the Sun is made up ...Read more

Surface and Atmosphere

The visible solar atmosphere consists of three regions: the photosphere, the chromosphere, ...Read more

Solar Activity

The Sun is not a quiet place, but one that exhibits sudden releases of energy. One of the ...Read more

Sunspots

Sunspots are dark, planet-sized regions that appear on the "surface" of the Sun. Sunspots are ...Read more

The Sun's Poles

Like Earth, the Sun has a North Pole, a South Pole, and an equator. The poles of the Sun are ...Read more

Solar Eclipses

An eclipse of the Sun occurs when the Earth passes through the Moon's shadow. A total eclipse ...Read more

Solar Magnetic Field

The Sun has a very large and very complex magnetic field. The magnetic field at an average ...Read more

Radiation

Radiation comes in two basic types: electromagnetic radiation transmitted by photons, and particle ...Read more

Fate of the Sun

In about 5 billion years, the hydrogen in the center of the Sun will start to run out. ...Read more

Culture, Myth, and Arts

Many cultures around the world have interesting myths about the Sun, reflecting its importance ...Read more

More about The Sun

Historical Events

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Did you know?

Did you know that the number of spots on the Sun's surface changes over a cycle of about 11 years?

Did you know that the Celtic Sun god, Lugh, threw a magic stone that killed Balor, the god of the underworld?

 

Earth and Space Science Concept of the Day

Do you know what this word or phrase means?

Orographic lift
xOrographic lift : Occurs when an air mass is forced to rise over geographic relief from a lower elevation. As the air mass rises it expands and cools adiabatically, which can raise the relative humidity to 100%, create clouds and precipitation.

Click on the word to find out!

Research Highlights

Triggers of Volcanic Eruptions in Oregon's Mount Hood Investigated

Scientists have learned that Mount Hood, Oregon's tallest mountain, has erupted in the past due to the mixing of two different types of magma. "The data will help give us a better road map to what a future...Read more


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