How the corona gets so hot remains a scientific mystery, which is partly why NASA launched its Parker Solar Probe , the fastest spacecraft ever built, and the first ever sent into the corona. In addition to light, the sun radiates heat and a steady stream of charged particles known as the solar wind.
The wind blows about miles kilometers a second throughout the solar system , extending the sun's magnetic field out more than 10 billion miles.
Beyond that distance, the solar wind gives way to the colder, dense material that drifts in between stars , forming a boundary called the heliopause. So far, just two spacecraft—Voyager 1 and Voyager 2 —have crossed this cosmic threshold, which defines the start of interstellar space. Every so often, a patch of particles will burst from the sun in a solar flare, which can disrupt satellite communications and knock out power on Earth.
Flares usually stem from the activity of sunspots, cool regions of the photosphere that form and dissipate as the sun's internal magnetic field shifts. Solar flares and sunspots obey a regular cycle, rising and falling in number every 11 years as the poles of the sun's magnetic field flip back and forth. Sometimes, the sun will also launch huge bubbles of magnetized particles from its corona, in events called coronal mass ejections CMEs. Some CMEs can grow as large as the sun itself and fling as much as a billion tons of material in a given direction.
As they rush from the sun, CMEs can send huge shockwaves through the solar wind. If a CME collided with Earth, its particles could pack enough power to fry electronics in orbit and on Earth's surface. Like many energy sources, the sun will not last forever. It has already used up nearly half of the hydrogen in its core.
The sun will continue to burn through the hydrogen for another five billion years or so, and then helium will become its primary fuel. At that point, the sun will expand to about a hundred times its current size, swallowing Mercury and Venus—and maybe Earth. It will burn as a red giant star for another billion years and then collapse into a white dwarf star. All rights reserved. Characteristics of the sun The sun resides some 26, light-years from the Milky Way's center, in a tendril of our home galaxy known as the Orion Arm.
ALMA - Protoplanetary disks. Share Tweet Email. Read This Next Wild parakeets have taken a liking to London. Animals Wild Cities Wild parakeets have taken a liking to London Love them or hate them, there's no denying their growing numbers have added an explosion of color to the city's streets. India bets its energy future on solar—in ways both small and big. Environment Planet Possible India bets its energy future on solar—in ways both small and big Grassroots efforts are bringing solar panels to rural villages without electricity, while massive solar arrays are being built across the country.
Epic floods leave South Sudanese to face disease and starvation. An H-R diagram takes a set of stars and plots their luminosities relative to the Sun versus their surface temperatures. Note that the temperature scale on the H-R diagram in Figure 1 runs backwards, right to left, and that the luminosity axis is highly compressed. Historically, this was how the first H-R diagram was constructed, so now they all are.
When done for a large sample of stars, we find that the overwhelming majority of the stars fall along a single, remarkably narrow band that runs from the bottom-right to the top-left: that is, from dim and red to bright and white-hot. Astronomers call this band the Main Sequence , and hence any star along the band is called a main-sequence star. Stars with very low masses as little as 7. They must lie at the lower right. This part of the H-R diagram corresponds to extremely low luminosity — as little as a ten thousandth that of the Sun — and low surface temperature, equivalent to the dull orange-yellow glow of molten metal.
These stars do not have enough mass to create the pressure necessary to make the nuclear burning in their cores go any faster. High-mass stars upwards of 40 solar masses reside at the upper left, as they must. Contrary to the low-mass stars, their immense masses and high central pressures give rise to giants that can be , times more luminous than the Sun, and so hot that they give off more energy in the ultraviolet than they do as visible light.
The Sun lies almost exactly halfway between these extremes, and thus it is neither extremely dim nor extremely bright as stars go. It shines with a bright yellowish-white color. The one-to-one nature between mass and hydrostatic equilibrium means that as you vary the mass of a star, all you can do is slide along a single, predetermined track with respect to all its other physical properties.
This track is exactly the main sequence. But now that I've said that, a second look at the H-R diagram reveals that there is a smattering of stars well off the main sequence: they are concentrated in "islands" at the upper right and lower left. Since the stars at the upper right are very luminous yet nonetheless have cool, reddish surfaces, astronomers call them red giants.
Similarly, since the stars at the lower left are very dim yet also white-hot, they are called white dwarfs. We have met the white dwarfs already, in a theoretical way. Now let's see where the real ones come from. The Sun is classified as a G2 star. Red Giants And White Dwarfs Red giants and white dwarfs come about because stars, like people, change with age and eventually die.
For people, the cause of aging is the deterioration of biological functions. For a star, the cause is the inevitable energy crisis as it begins to run out of nuclear fuel. Since its birth 4. This causes the nuclear reactions to run a little hotter. The Sun brightens. This brightening process moves along very slowly at first, when there is still ample hydrogen remaining to be burnt at the center of the star. Like all stars, our Sun will eventually run out of energy. When it starts to die, the Sun will expand into a red giant star, becoming so large that it will engulf Mercury and Venus, and possibly Earth as well.
Scientists predict the Sun is a little less than halfway through its lifetime and will last another 5 billion years or so before it becomes a white dwarf. The Sun has several regions. The interior regions include the core, the radiative zone, and the convection zone. Once material leaves the corona at supersonic speeds, it becomes the solar wind, which forms a huge magnetic "bubble" around the Sun, called the heliosphere.
The heliosphere extends beyond the orbit of the planets in our solar system. Outside the heliosphere is interstellar space. The core is the hottest part of the Sun. That is approximately 8 times the density of gold Energy from the core is carried outward by radiation. This radiation bounces around the radiative zone, taking about , years to get from the core to the top of the convection zone. Moving outward, in the convection zone, the temperature drops below 3.
Here, large bubbles of hot plasma a soup of ionized atoms move upward toward the photosphere, which is the layer we think of as the Sun's surface. The part of the Sun commonly called its surface is the photosphere.
The word photosphere means "light sphere" — which is apt because this is the layer that emits the most visible light. Hopefully, it goes without saying — but never look directly at the Sun without protecting your eyes. Although we call it the surface, the photosphere is actually the first layer of the solar atmosphere.
It's about miles thick, with temperatures reaching about 10, degrees Fahrenheit 5, degrees Celsius. That's much cooler than the blazing core, but it's still hot enough to make carbon — like diamonds and graphite — not just melt, but boil.
Most of the Sun's radiation escapes outward from the photosphere into space. Above the photosphere is the chromosphere, the transition zone, and the corona. Not all scientists refer to the transition zone as its own region — it is simply the thin layer where the chromosphere rapidly heats and becomes the corona.
Visible light from these top regions of the Sun is usually too weak to be seen against the brighter photosphere, but during total solar eclipses, when the Moon covers the photosphere, the chromosphere looks like a fine, red rim around the Sun, while the corona forms a beautiful white crown "corona" means crown in Latin and Spanish with plasma streamers narrowing outward, forming shapes that look like flower petals.
Imagine walking away from a bonfire only to get warmer. The source of coronal heating is a major unsolved puzzle in the study of the Sun. The Sun generates magnetic fields that extend out into space to form the interplanetary magnetic field — the magnetic field that pervades our solar system.
The field is carried through the solar system by the solar wind — a stream of electrically charged gas blowing outward from the Sun in all directions. Since the Sun rotates, the magnetic field spins out into a large rotating spiral, known as the Parker spiral. This spiral has a shape something like the pattern of water from a rotating garden sprinkler. The Sun doesn't behave the same way all the time.
It goes through phases of high and low activity, which make up the solar cycle. During this cycle, the Sun's photosphere, chromosphere, and corona change from quiet and calm to violently active. Sunspots, eruptions called solar flares, and coronal mass ejections are common at solar maximum.
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