The Sun

The Sun Students will be able to: • Explain the role of the sun in the solar system • Describe the sun and its different layers and parts • Explain how the sun generates its own energy • Describe different solar activities The Sun Key Vocabulary • Chromosphere • Convective zone • Core • Corona • Nuclear fusion • Photosphere • Prominences • Radiative zone • Sunspots • Solar flare Structure of the Sun The Sun The sun is a typical yellow dwarf star. It is a giant ball of glowing gas with surface temperatures around 5500 K giving it a yellow glow. The Sun The Sun is the largest object within our solar system and makes up 99.8% of the system’s mass. The sun is located at the center of our solar system. Though massive, it is still not as large as other types of stars. The Sun Because of the sun’s massive size, it exerts strong gravitational force which is enough to hold the solar system together. The sun’s gravity keeps everything from the biggest planets to the smallest particles of debris in their orbits. The Sun The Sun is 1.39 million km in diameter and is 332 946 times more massive than Earth. Given the massive size of the sun, more than one million Earths could fit inside it if it was empty. Although heavier, the sun is less dense than Earth since it is mostly gaseous. Planets and sun size comparison by Lsmpascal The Sun Similar to Earth, the sun is composed of several layers beneath its surface. This is a result of the density difference between the sun’s component gases, hydrogen and helium, and of different processes taking place beneath the surface. The gases comprising the sun change to plasma due to extreme heat. The Sun The sun’s interior layers are different from each other, and each plays a part in producing the energy that the sun ultimately emits. The core is the innermost part of the sun. It functions as a nuclear reactor which produces the sun’s enormous energy. The Sun The sun’s core is extremely dense. It is approximately 20% of the size of the solar interior and is thought to have a temperature of approximately 15 million Kelvin, which makes it the hottest part of the sun. The Sun Surrounding the core is the sun’s radiative zone, a layer of dense plasma where energy produced at the core is radiated outward towards the surface. This region starts at about 25% of the distance to the solar surface and extends up to about 70% of the way to the surface. The Sun The energy generated in the core is transported through the radiative zone very slowly. It does not follow a straight path. Instead, the dense plasma bounces the energy rays around, making them change direction and lose some energy. The Sun The convective zone is the outermost layer of the sun’s interior. It is a thick layer approximately 200000 km deep that transports energy from the edge of the radiative zone to the sun’s surface. This zone is just beneath the sun’s surface where the plasma becomes too cool to carry energy directly. The Sun The energy from the radiative zone “boils” the convective zone plasma, forming large convection currents. The process is similar to a boiling pot of water, where the heat source is the radiative zone, and the bubbles are the convection currents. The Sun The sun does not have a solid surface since it is composed of gas. Instead , it has an atmosphere that is composed of several layers, mainly the photosphere, the chromosphere, and the corona. It is in these outer layers that the sun’s energy is detected as sunlight. The Sun The photosphere is defined as the deepest layer that can be directly observed and what can be considered as the sun’s surface. The boundary between the photosphere and the sun’s atmosphere is not clearly defined. The Sun Most of the photosphere is covered by granulation or the grainy appearance due to bright, bubbling granules of plasma. Aside from granulations, sunspots are also observed on the sun’s photosphere. Granulations and sunspots on photosphere. The Sun The chromosphere is the layer of the sun’s atmosphere that is just above the solar surface. Chromosphere is hotter than photosphere despite being farther from the sun’s interior. Scientists explain believe that heating mechanism depends on regular, but intermittent bursts of heat rather than on continuous gradual heating. The temperatures at this layer induce a reddish glow from the hydrogen plasma, which is drowned out by the sun’s brightness and is only observable around a total solar eclipse. The Sun The upper atmosphere of the sun is called the transition region which is invisible since it glows in ultraviolet light. Solar Eclipse by Luc Viatour . The Sun The outermost layer of the atmosphere is the corona which forms a delicate white halo around the sun. Similar to chromosphere, corona is most apparent during a total solar eclipse. The sun’s atmosphere get hotter away from the surface and the thickness of its layers is highly variable. The sun is a typical yellow large star. The Sun Comprehension check… Decide whether the given statement is true or false. The sun holds everything together in the solar system. The sun's atmosphere is hotter than its surface. The sun's energy is generated in the corona. The sun’s is huge ball of glowing gases. The Sun Comprehension check…Answers Decide whether the given statement is true or false. The sun is a typical yellow large star. false The sun holds everything together in the solar system. true The sun's atmosphere is hotter than its surface. true The sun's energy is generated in the corona. false The sun’s is huge ball of glowing gases. true Solar Activity The Sun The sun’s energy is a product of nuclear fusion, a reaction where two atoms collide under extreme conditions to form a single, heavier atom. The Sun Deep in the sun’s core, nuclear fusion converts hydrogen to helium, which generates energy. The Sun The sun’s core experiences incredible pressure due to the star’s mass and extreme temperatures. These conditions turn gas into plasma and fuse hydrogen atoms into helium. The Sun Particles of light called photons carry the energy from the core to the radiative zone to the top layer of the solar interior, the convective zone. The Sun In this zone, hot plasmas rise and fall like the ooze in a lava lamp, which transfers energy to the sun’s photosphere. The Sun The generation of energy in the sun’s core results in high temperatures on the sun’s surface. It has electrically charged gases that generate areas of powerful magnetic fields. The Sun Since the sun’s gases are constantly moving, they sometimes tangle, stretch and twist the magnetic fields. This motion creates a lot of activity on the sun’s surface, called solar activity. The Sun There are times that the sun’s surface is very active while other times, it seems to be quiet and passive. The is due to the different stages in the solar cycle, a nearly periodic 11-year changes in the sun’s magnetic activity. The Sun This means that every 11 years or so, the sun’s magnetic field completely flips, which also cause changes in solar activity. The Sun Various phenomena occur at the sun’s surface due to energy spikes or drops, producing a swirling, explosive surface. These phenomena can have effects here on Earth, so scientists closely monitor solar activity on a daily basis. The Sun sunspots Sunspots are areas that appear dark on the surface of the sun. They appear dark because they are “cooler” than other parts of the sun’s surface. The Sun sunspots This is due to the fact they were formed at areas where magnetic fields are particularly strong. These magnetic fields are so strong that they keep some of the heat within the sun from reaching the surface. The Sun solar flare A sudden explosion of energy near sunspots can happen due to magnetic field lines that often tangle, cross, and reorganize. This high-energy explosion at the sun’s surface is called solar flare. The Sun solar flare Flares are our solar system’s largest explosive events. They are seen as bright areas on the sun and can last from minutes to hours. The Sun Solar flares release a lot of radiation into space. If a solar flare is very intense, the radiation it releases can interfere with radio communication and Global Positioning System (GPS) navigation on Earth. The Sun This may also cause temporary operational anomalies and damage to space crafts and satellites. The Sun prominence Sometimes huge streams of plasma explode from the surface of the sun and curl back down. These are called prominences. The Sun prominence Prominences are anchored to the photosphere and extend towards the corona. The red-glowing looped material is plasma, a hot gas comprised of electrically charged hydrogen and helium. The Sun Coronal mass ejection (CME) Another solar activity is coronal mass ejection (CME) which is a significant release of plasma and accompanying magnetic field from the solar corona following a solar flare and are normally present during prominences. The Sun Coronal mass ejection (CME) CMEs are huge bubbles of radiations and particles from the sun. They explode into space at very high speed when the sun’s magnetic field lines suddenly reorganize. The Sun Auroras or bright lights in the sky are triggered mainly by CME. When plasma particles from a CME reach earth and collide with Earth’s magnetic field, auroras are formed. The Sun When CME is too strong, it can interfere in power utility grids which can cause electricity shortages and power outages. The Sun Solar wind is a constant stream of energized, charged particles flowing outward from the sun through the solar system. Solar wind The Sun Solar wind This plasma is primarily composed of electrons and protons. Since it is a constant phenomenon in the solar system, it has an effect on Earth too. The Sun Earth’s magnetosphere Magnetosphere is an area surrounding Earth that is created by its magnetic field. This acts like a shield to protect Earth from most of the particles that the sun emits. For instance, when CME or solar wind arrives at Earth, it buffets the magnetosphere. The Sun A geomagnetic storm is a major disturbance of Earth’s magnetosphere that occurs when there is a very efficient exchange of energy from the solar wind into the space environment surrounding Earth. Geomagnetic storm The Sun These storms result from variations in the solar wind that produce major changes in Earth’s magnetosphere. Geomagnetic storm The Sun Geomagnetic storm Geomagnetic storms can impact the activities on Earth. Like other solar activities, it can disrupt radio and satellite communications, GPS navigation, and power grid operations. The formation of auroras are also attributed to geomagnetic storms. The Sun Comprehension check… Answer the following questions. How does the sun generate its energy? Why are there many activities on the sun’s surface? How do solar activities impact Earth? The Sun Comprehension check…Answers Answer the following questions. How does the sun generate its energy? In the sun’s core, nuclear fusion converts hydrogen to helium which generates energy. Why are there many activities on the sun’s surface? Different activities occur at the sun’s surface due to energy spikes or drops, producing a swirling, explosive surface. How do solar activities impact Earth? Solar activities affect radio communication, GPS navigation, and power grid operation here on Earth.