For every 1 million atoms of hydrogen in the sun, there are 98, of helium, of oxygen, of carbon, of neon, of nitrogen, 40 of magnesium, 35 of iron and 35 of silicon. Related: What is the sun made of? Sunspots are relatively cool, dark features on the sun's surface that are often roughly circular. They emerge where dense bundles of magnetic field lines from the sun's interior break through the surface. The number of sunspots varies as solar magnetic activity does — the change in this number, from a minimum of none to a maximum of roughly sunspots or clusters of sunspots and then back to a minimum, is known as the solar cycle , and averages about 11 years long.
At the end of a cycle, the magnetic field rapidly reverses its polarity. Related: Largest sunspot in 24 years wows scientists, but also mystifies. Ancient cultures often modified natural rock formations or built stone monuments to mark the motions of the sun and moon, charting the seasons, creating calendars and monitoring eclipses.
Many believed the sun revolved around the Earth, with the ancient Greek scholar Ptolemy formalizing this "geocentric" model in B. Then, in , Nicolaus Copernicus described a heliocentric sun-centered model of the solar system, and in , Galileo Galilei 's discovery of Jupiter's moons confirmed that not all heavenly bodies circled Earth.
To learn more about how the sun and other stars work, after early observations using rockets, scientists began studying the sun from Earth orbit. Seven of them were successful, and analyzed the sun at ultraviolet and X-ray wavelengths and photographed the super-hot corona, among other achievements. The Solar and Heliospheric Observatory SOHO , which last year celebrated 25 years in space, has been one of the most important solar missions to date. Designed to study the solar wind, as well as the sun's outer layers and interior structure, it has imaged the structure of sunspots below the surface, measured the acceleration of the solar wind, discovered coronal waves and solar tornadoes, found more than 1, comets, and revolutionized our ability to forecast space weather.
The Solar Dynamics Observatory SDO , launched in , has returned never-before-seen details of material streaming outward and away from sunspots, as well as extreme close-ups of activity on the sun's surface and the first high-resolution measurements of solar flares in a broad range of extreme ultraviolet wavelengths.
Both of these spacecraft orbit the sun closer than any spacecraft before, taking complementary measurements of the environment in the vicinity of the star. During its close passes, the Parker Solar Probe dives into the sun's outer atmosphere, the corona, having to withstand temperatures hotter than one million degrees Fahrenheit.
At its nearest, the Parker Solar Probe will fly merely 4 million miles 6. This plasma rotates at different speeds on different parts of the Sun. At its equator, the Sun completes one rotation in 25 Earth days. At its poles, the Sun rotates once on its axis every 36 Earth days.
The part of the Sun we see from Earth — the part we call the surface — is the photosphere. This is where we see features such as solar prominences, flares, and coronal mass ejections. The latter two are giant explosions of energy and particles that can reach Earth. The Sun would have been surrounded by a disk of gas and dust early in its history when the solar system was first forming 4.
Some of that dust is still around today, in several dust rings that circle the Sun. They trace the orbits of planets, whose gravity tugs dust into place around the Sun. The temperature in the Sun's core is about 27 million degrees Fahrenheit 15 million degrees Celsius — hot enough to sustain nuclear fusion. This creates outward pressure that supports the star's gigantic mass, keeping it from collapsing.
The Sun has inspired us since ancient times. Countless musicians have written songs about the Sun. If you're Superman or a fellow Kryptonian, your powers are heightened by the yellow glow of our Sun, and you can even dispose of dangerous materials, as Superman and Superboy did, by hurling them into the Sun. Astronauts are supposed to use a bomb to divert the flare.
It still has about 5,,,—five billion—years to go. When those five billion years are up, the Sun will become a red giant. That means the Sun will get bigger and cooler at the same time.
When that happens, it will be different than the Sun we know today. As a red giant, our Sun will become about 2, times brighter than it is now! How Old Is the Sun? While our planet is in some ways a mere speck in the vast cosmos, we have a lot of company out there. It seems that we live in a universe packed with planets — a web of countless stars accompanied by families of objects, perhaps some with life of their own.
There are many planetary systems like ours in the universe, with planets orbiting a host star. Our planetary system is named the "solar system" because our Sun is named Sol, after the Latin word for Sun, "solis," and anything related to the Sun we call "solar. Our solar system extends much farther than the eight planets that orbit the Sun.
The solar system also includes the Kuiper Belt that lies past Neptune's orbit. This is a sparsely occupied ring of icy bodies, almost all smaller than the most popular Kuiper Belt Object — dwarf planet Pluto. Beyond the fringes of the Kuiper Belt is the Oort Cloud. This giant spherical shell surrounds our solar system. It has never been directly observed, but its existence is predicted based on mathematical models and observations of comets that likely originate there.
The Oort Cloud is made of icy pieces of space debris - some bigger than mountains — orbiting our Sun as far as 1. This shell of material is thick, extending from 5, astronomical units to , astronomical units. One astronomical unit or AU is the distance from the Sun to Earth, or about 93 million miles million kilometers.
The Oort Cloud is the boundary of the Sun's gravitational influence, where orbiting objects can turn around and return closer to our Sun. The Sun's heliosphere doesn't extend quite as far. The heliosphere is the bubble created by the solar wind — a stream of electrically charged gas blowing outward from the Sun in all directions. The boundary where the solar wind is abruptly slowed by pressure from interstellar gases is called the termination shock.
This edge occurs between astronomical units.
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