Consider the Earth, the Moon, and also all the other planets in our solar system. Think around the mass the all those objects must have when they space all added together. Added all together, however, they account for only 0.2% the the total mass of the solar system. The Sun makes up the staying 99.8% of every the massive in the solar device (Figure 24.17)! The sun is the center of the solar system and the largest object in the solar system. Our sunlight is a star that provides light and also heat and supports practically all life ~ above Earth.

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In this great you will certainly learn around the attributes of the Sun. Us will discuss the ingredient of the Sun, that is atmosphere, and also some that its surface features.


Figure 24.17: The Sun.

Layers that the Sun

The sun is a sphere, however unlike the Earth and the Moon, is not solid. Most atoms in the sunlight exist as plasma, or a fourth state of matter consisted of of superheated gas with an electric charge. Our sunlight consists almost entirely of the facets hydrogen and also helium. Because the sunlight is no solid, it does not have a defined outer boundary. That does, however, have a definite internal structure. Over there are number of identifiable class of the Sun:

The core is the innermost or central layer that the Sun. The core is plasma, however moves similarly to a gas. The temperature is about 27 million degrees Celsius. In the core, nuclear reactions combine hydrogen atoms to form helium, releasing large amounts of energy in the process. The power released then starts to relocate outward, towards the outer layers of the Sun.

The radiative zone is just external the core, which has actually a temperature of about 7 million degrees Celsius. The energy released in the main point travels extremely slowly with the radiative zone. Corpuscle of light referred to as photons deserve to only take trip a couple of millimeters before they hit one more particle in the Sun, are soaked up and climate released again. It deserve to take a photon as lengthy as 50 million year to travel all the way through the radiative zone.

The convection zone surrounds the radiative zone. In the convection zone, warm material from close to the Sun’s facility rises, cools in ~ the surface, and also then plunges earlier downward to receive more heat from the radiative zone. This motion helps to develop solar flares and sunspots, i m sorry we’ll learn more about in a bit. These very first three layers consist of what we would certainly actually contact “the Sun”. The next three layers consist of the Sun’s atmosphere. The course, there are no hard layers to any part of the Sun, for this reason these boundaries are fuzzy and also indistinct.

The Sun’s “Atmosphere”

The photosphere is the visible surface of the sun (Figure 24.18). This is the region of the sunlight that emits sunlight. It’s also one that the coolest great of the Sun—only around 6700°C. Looking at a picture of the Sun’s surface, you have the right to see the it has several different colors; oranges, yellow and reds, providing it a grainy appearance. We cannot view this once we glance easily at the Sun. Our eyes can’t emphasis that quickly and also the sun is as well bright for us to look at for much more than a quick moment. Looking in ~ the sunlight for any type of length that time can cause blindness, so don’t shot it! sunshine is emitted from the Sun’s photosphere. A fraction of the light that travels from the sunlight reaches Earth. The travels as light in a variety of wavelengths, including visible light, ultraviolet, and also infrared radiation. Visible irradiate is all the light we have the right to see with our eyes. Us can’t see ultraviolet and also infrared radiation, yet their impacts can still be detected. Because that example, a sunburn is resulted in by ultraviolet radiation when you invest too lot time in the Sun.


The chromosphere is the zone about 2,000 kilometers thick the lies directly above the photosphere. The chromosphere is a thin region of the Sun’s environment that glows red together it is heated by energy from the photosphere. Temperature in the chromosphere range from about 4000°C to around 10,000°C. Jets of gas fire up through the chromosphere at speeds up to 72,000 kilometers every hour, getting to heights together high as 10,000 kilometers.

The corona is the outermost class of the Sun and also is the outermost part of that atmosphere. That is the Sun’s halo or “crown”. It has actually a temperature that 2 come 5 million degrees Celsius and also is lot hotter than the visible surface of the Sun, or photosphere. The corona extends numerous kilometers into space. If you ever before have the possibility to view a full solar eclipse, girlfriend will be able to see the Sun’s corona, bright out right into space.

In the Sun’s core, nuclear fusion reactions generate power by converting hydrogen come helium. Blend is a process where the nuclei that atoms sign up with together to kind a heavier chemical element. Blend reactions in the Sun’s core create energy, i beg your pardon we endure as heat and also light. The remainder of the sunlight is heated by movement of heat power outward indigenous the core. Light energy from the sunlight is emitted native the photosphere. It travels through space, and some of the reaches the Earth. The sunlight is the resource of almost all the power on Earth and sunlight powers photosynthesis, and also warming and also illuminating ours Earth.

Surface functions of the Sun

The most noticeable surface feature of the sun is the visibility of sunspots, which room cooler, darker areas on the Sun’s surface. Sunspots are just visible with special light-filtering lenses. They exhibit extreme magnetic activity. These areas are cooler and darker because loops the the Sun’s magnetic ar break with the surface and disrupt the smooth transfer of warmth from lower layers. Sunspots usually happen in pairs. Once a loop of the Sun’s magnetic field breaks through the surface, it typically creates a sunspot both whereby it come out and one where it goes ago in again. Sunspots usually occur in 11 year cycles, beginning when the variety of sunspots is at a minimum, raising to a maximum variety of sunspots and then gradually decreasing come a minimum number of sunspots again.

If a loop of the sun’s magnetic field snaps and breaks, it creates solar flares, which space violent explosions the release large amounts of energy (Figure 24.19). They relax streams of highly energetic particles that consist of the solar wind. The solar wind deserve to be dangerous come spacecraft and astronauts. It sends out huge amounts of radiation, i m sorry can harm the human being body. Solar flares have actually knocked out entire power grids and also can annoy radio, satellite, and cell phone call communications.


Another extremely visible attribute on the Sun are solar prominences. If plasma flows along a loop that the Sun’s magnetic ar from sunspot come sunspot, it creates a glow arch the reaches countless kilometers right into the Sun’s atmosphere. Prominences deserve to last because that a work to number of months. Prominences are also visible throughout a total solar eclipse.

A beautiful and also mysterious result of the Sun’s electrically charged particles room auroras, which form around the polar areas high in Earth’s atmosphere. Gases in Earth’s environment are excited by the electrically fee particles the the solar wind and also glow producing curtains the light, which bend and adjust as friend watch.

Lesson Summary

The mass of the sun is tremendous. It provides up 99.8% that the mass of ours solar system.The sunlight is largely made of hydrogen v smaller quantities of helium in the kind of plasma.The main component of the Sun has actually three layers: the core, the radiative zone, and also the convection zone.The Sun’s atmosphere likewise has three layers: the photosphere, the chromosphere, and also the corona.Nuclear fusion of hydrogen in the core of the sunlight produces tremendous quantities of energy that radiate out from the Sun.Some features of the Sun’s surface encompass sunspots, solar flares, and also prominences.

Review Questions

In what method does the sun support every life ~ above Earth?Which two aspects make up the Sun almost in entirety?Which procedure is the resource of warm in the Sun and also where go it take it place?Some researchers would prefer to plan a expedition to take people to Mars. Among the points standing in the method of our ability to perform this is solar wind. Why will certainly we need to be involved with solar wind?Describe just how movements in the convection zone contribute to solar flares.Do you think fusion reactions in the Sun’s main point will proceed forever and go on v no end? define your answer.

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chromosphereThin layer of the Sun’s setting that lies directly above the photosphere; glows red.convection zoneLayer of the sun that surrounding the Radiative Zone; power moves together flowing cells of gas.coreInnermost or central layer the the Sun.coronaOutermost layer of the Sun; a plasma the extends numerous kilometers right into space.nuclear fusionThe merging with each other of the nuclei of atoms to type new, more heavier chemical elements; vast amounts the nuclear energy are released in the process.photosphereLayer the the sun that us see; the visible surface ar of the Sun.photosynthesisThe process that green plants usage to convert sunlight to energy.plasmaA high energy, high temperature form of matter. Electron are gotten rid of from atoms, leaving each atom with an electrical charge.radiationElectromagnetic energy; photons.radiative zoneLayer the the Sun automatically surrounding the core; energy moves atom to atom as electromagnetic flareA violent explode on the Sun’s windA currently of radiation emitted through a solar flare. The solar wind extends numerous kilometers out into space and can even reach the Earth.sunspotsCooler, darker areas on the Sun’s surface that have lower temperature than bordering areas; sunspots usually take place in pairs.

Points to Consider

If something were to suddenly reason nuclear combination to protect against in the Sun, just how would us know?Are over there any types of dangerous energy from the Sun? What might be affected by them?If the sun is every made that gases choose hydrogen and also helium, how have the right to it have actually layers?