Consider the Earth, the Moon, and also all the various other planets in ours solar system. Think about the mass the all those objects must have actually when they space all included together. Included all together, however, they account for just 0.2% the the full mass the the solar system. The Sun provides up the staying 99.8% of all the fixed in the solar mechanism (Figure 24.17)! The sun is the center of the solar system and also the biggest object in the solar system. Our sun is a star that offers light and heat and also supports practically all life ~ above Earth.

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In this class you will certainly learn about the functions of the Sun. Us will comment on the composition of the Sun, that atmosphere, and some of its surface ar features.


Figure 24.17: The Sun.

Layers the the Sun

The sunlight is a sphere, yet unlike the Earth and also the Moon, is not solid. Many atoms in the sun exist as plasma, or a 4th state the matter comprised of superheated gas through an electrical charge. Our sunlight consists virtually entirely that the aspects hydrogen and helium. Due to the fact that the sunlight is not solid, that does not have actually a defined outer boundary. The does, however, have actually a definite internal structure. There are numerous identifiable layers of the Sun:

The core is the innermost or central layer of the Sun. The core is plasma, yet moves likewise to a gas. Its temperature is approximately 27 million degrees Celsius. In the core, atom reactions combine hydrogen atom to form helium, releasing huge amounts of energy in the process. The energy released then starts to move outward, in the direction of the external layers the the Sun.

The radiative zone is just external the core, which has a temperature of around 7 million degrees Celsius. The energy released in the core travels exceptionally slowly with the radiative zone. Corpuscle of light referred to as photons deserve to only take trip a few millimeters prior to they hit an additional particle in the Sun, are soaked up and climate released again. It can take a photon as lengthy as 50 million year to travel all the means through the radiative zone.

The convection zone surrounds the radiative zone. In the convection zone, warm material from near the Sun’s facility rises, cools at the surface, and also then plunges earlier downward come receive more heat from the radiative zone. This activity helps to develop solar flares and also sunspots, i m sorry we’ll learn an ext about in a bit. These an initial three layers comprise what we would certainly actually speak to “the Sun”. The following three layers consist of the Sun’s atmosphere. That course, there space no hard layers come any part of the Sun, for this reason these boundaries are fuzzy and indistinct.

The Sun’s “Atmosphere”

The photosphere is the visible surface ar of the sunlight (Figure 24.18). This is the region of the sunlight that emits sunlight. It’s likewise one that the coolest great of the Sun—only around 6700°C. Looking in ~ a photo of the Sun’s surface, you have the right to see that it has several various colors; oranges, yellow and reds, providing it a grainy appearance. Us cannot check out this when we glance quickly at the Sun. Our eye can’t emphasis that quickly and the sunlight is also bright for us to look at for more than a brief moment. Looking in ~ the sun for any type of length of time can reason blindness, for this reason don’t try it! sunlight is emitted from the Sun’s photosphere. A portion of the light that travels native the sun reaches Earth. The travels as light in a range of wavelengths, including visible light, ultraviolet, and infrared radiation. Visible light is all the light we deserve to see with our eyes. We can’t view ultraviolet and also infrared radiation, but their effects can still it is in detected. Because that example, a sunburn is resulted in by ultraviolet radiation as soon as you invest too lot time in the Sun.


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

The corona is the outermost layer of the Sun and is the outermost component of that atmosphere. It is the Sun’s aur or “crown”. It has actually a temperature the 2 to 5 million levels Celsius and also is much hotter than the visible surface ar of the Sun, or photosphere. The corona extends countless kilometers into space. If you ever before have the opportunity to check out a total solar eclipse, you will have the ability 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. Fusion is a process where the nuclei of atoms sign up with together to type a more heavier chemical element. Blend reactions in the Sun’s core develop energy, i m sorry we endure as heat and also light. The rest of the sun is heated by motion of heat energy outward indigenous the core. Light power from the sunlight is emitted native the photosphere. That travels v space, and some of that reaches the Earth. The sun is the resource of almost all the power on Earth and sunlight powers photosynthesis, as well as warming and illuminating our Earth.

Surface attributes of the Sun

The many noticeable surface attribute of the sunlight is the visibility of sunspots, which space cooler, darker locations on the Sun’s surface. Sunspots are only visible with special light-filtering lenses. They exhibit extreme magnetic activity. These locations are cooler and also darker due to the fact that loops of the Sun’s magnetic field break with the surface and also disrupt the smooth deliver of heat from lower layers. Sunspots usually take place in pairs. Once a loop of the Sun’s magnetic ar breaks v the surface, it normally creates a sunspot both wherein it comes out and also one whereby it goes ago in again. Sunspots usually happen in 11 year cycles, start when the number of sunspots is in ~ a minimum, boosting to a maximum variety of sunspots and then progressively decreasing to a minimum variety of sunspots again.

If a loop the the sun’s magnetic ar snaps and breaks, it creates solar flares, which room violent explosions the release substantial amounts of power (Figure 24.19). They release streams of highly energetic particles that comprise the solar wind. The solar wind have the right to be dangerous come spacecraft and astronauts. It sends out out large amounts the radiation, which can injury the person body. Solar flares have actually knocked out entire power grids and can disturb radio, satellite, and cell phone communications.


Another highly visible feature on the Sun are solar prominences. If plasma flows follow me a loop of the Sun’s magnetic ar from sunspot come sunspot, it develops a glow arch the reaches countless kilometers into the Sun’s atmosphere. Prominences can last for a work to numerous months. Prominences are also visible throughout a full solar eclipse.

A beautiful and mysterious impact of the Sun’s electrically charged particles are auroras, which kind around the polar areas high in Earth’s atmosphere. Gases in Earth’s setting are excited by the electrically charged particles the the solar wind and glow creating curtains that light, which bending and readjust as you watch.

Lesson Summary

The massive of the sun is tremendous. It renders up 99.8% of the fixed of our solar system.The sunlight is greatly made of hydrogen v smaller amounts of helium in the kind of plasma.The main component of the Sun has three layers: the core, the radiative zone, and also the convection zone.The Sun’s atmosphere additionally has 3 layers: the photosphere, the chromosphere, and also the corona.Nuclear combination of hydrogen in the core of the sun produces tremendous quantities of energy that radiate the end from the Sun.Some functions of the Sun’s surface incorporate sunspots, solar flares, and prominences.

Review Questions

In what method does the sun support every life ~ above Earth?Which two facets make up the Sun nearly in entirety?Which procedure is the resource of warm in the Sun and where go it take it place?Some researchers would choose to arrangement a trip to take humans to Mars. Among the points standing in the means of our ability to carry out this is solar wind. Why will we need to be came to with solar wind?Describe just how movements in the convection zone contribute to solar flares.Do friend think blend reactions in the Sun’s main point will continue forever and also go on with no end? explain your answer.

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chromosphereThin layer of the Sun’s setting that lies directly above the photosphere; glows red.convection zoneLayer the the sun that surrounding the Radiative Zone; energy moves as flowing cells of gas.coreInnermost or main layer the the Sun.coronaOutermost great of the Sun; a plasma the extends millions of kilometers right into space.nuclear fusionThe merging together of the nuclei of atom to type new, more heavier chemical elements; huge amounts that nuclear energy are released in the process.photosphereLayer that the sun that we see; the visible surface of the Sun.photosynthesisThe process that green plants use to convert sunlight to energy.plasmaA high energy, high temperature form of matter. Electron are removed from atoms, leaving every atom v an electrical charge.radiationElectromagnetic energy; photons.radiative zoneLayer that the Sun immediately surrounding the core; power moves atom to atom as electromagnetic flareA violent explosion on the Sun’s windA present of radiation emitted by a solar flare. The solar wind extends numerous kilometers out into room and can even reach the Earth.sunspotsCooler, darker locations on the Sun’s surface that have lower temperatures than surrounding areas; sunspots usually take place in pairs.

Points come Consider

If something were to suddenly cause nuclear combination to stop in the Sun, exactly how would we know?Are there any types of dangerous energy from the Sun? What might be influenced by them?If the sunlight is all made of gases choose hydrogen and also helium, how deserve to it have actually layers?