Dhristi JEE 2022-24

Corona of Sun Meaning

Our Sun is surrounded by an atmosphere, which is a layer of gases. The corona is the Sun's atmosphere's outermost layer. The brilliant brightness of the Sun's surface frequently obscures the corona. This makes it impossible to see without the use of specialised equipment. The corona, on the other hand, may be observed during a total solar eclipse. The moon passes between the Earth and the Sun during a complete solar eclipse. When this occurs, the moon conceals the Sun's strong brightness. The eclipsed Sun is then surrounded by a dazzling white corona. In this post, we'll look at what coronal meaning is, how solar eclipses affect the corona and solar wind.


Corona of Sun

The corona is the outermost portion of the Sun's atmosphere, made mostly of plasma (hot ionised gas). It has a temperature of around two million kelvins and a very low density. As a result of the Sun's magnetic field, the corona's size and form change all the time. The solar wind, which sweeps radially outward through the whole solar system, is created by coronal gas expansion and only reaches the heliopause. Despite its high temperature, the corona generates very little heat due to its low density; that is, the component gas molecules are so sparse that the energy content per cubic centimetre is significantly less than that of the Sun's core.

The corona radiates only about half as brilliantly as the Moon and is generally invisible to the naked eye due to the brilliance of the solar surface. During a total solar eclipse, the Moon blocks out the light from the photosphere, allowing for naked-eye observations of the corona and this is one of the major effects of solar eclipse on corona. The corona may also be observed under non-eclipse conditions using a coronagraph, which is a specialised telescopic equipment.


Reason for the Hotness of the Corona of the Sun

The high temperatures of the corona are a bit of a mystery. Assume you're sitting close to a bonfire. It's comfortable and toasty. However, as you move away from the fire, you feel a lot better. This appears to be the reverse of what appears to occur on the Sun. For a long time, astronomers have been attempting to answer this puzzle. The corona is located in the Sun's outer atmosphere, far from its surface. The corona, on the other hand, is hundreds of times hotter than the Sun's surface.

One conceivable solution might have come from a NASA project named IRIS. The expedition detected "heat bombs," which are packets of extremely hot material that flow from the Sun into the corona. The heat bombs burst in the corona, releasing their energy as heat. However, scientists believe that this is merely one of several ways in which the corona is heated.


Solar Wind

The solar wind is a stream of particles that flows throughout the solar system at roughly one million miles per hour after leaving the sun. The solar wind, initially proposed by University of Chicago professor Eugene Parker in the 1950s, is visible in the halo encircling the sun during an eclipse and, on rare occasions, when the particles collide with the Earth's atmosphere, resulting in the aurora borealis, or northern lights. While the solar wind protects Earth from potentially harmful space particles, storms may also damage our satellite and communications networks.

The Sun, like all stars, loses material by a stellar wind. Stellar winds are fast-moving material flows that are ejected from stars (protons, electrons, and atoms of heavier metals). These winds are distinguished by a continuous outflow of material flowing at velocities ranging from 20 to 2,000 km/sec. In the case of the Sun, wind speeds range from 200 to 300 km/sec in tranquil parts to 700 km/sec in coronal holes and active regions.

Stellar winds have different sources, ejection rates, and velocity depending on the mass of the star. The extraordinarily high temperature (millions of degrees Kelvin) of the corona causes the wind in comparatively cold, low-mass stars like the Sun. This high temperature is thought to be the result of magnetic field interactions at the star's surface, giving enough energy for coronal gas to escape the star's gravitational pull as a wind.

Although stars of this sort release a small proportion of their mass as a stellar wind each year (for example, only 1 part in 1014 of the Sun's mass is ejected in this fashion each year), this nevertheless implies material losses of millions of tonnes each second. Stars like our Sun lose only a fraction of a percent of their mass through stellar winds during their entire lifespan.

When the solar wind interacts with the Earth's upper atmosphere and magnetic field, it produces a variety of phenomena, the most visible of which are the aurorae (Borealis and Australis). These are formed when solar wind particles propelled by the Earth's magnetic field clash with upper-atmosphere atoms and molecules. Light at specific wavelengths is emitted as atoms and molecules de-excite. A similar effect may be witnessed at Jupiter's magnetic poles.

Book your Free Demo session
Get a flavour of LIVE classes here at Vedantu
FAQs (Frequently Asked Questions)

1. What does the sun's coronal meaning ?

Ans: Coronal is a white or colourful circle or a series of concentric rings of light observed around a luminous entity, most notably the sun or moon. Such a small-radius circle or sequence of circles with a colour spectrum spanning from blue inside to red outside, caused by diffraction caused by thin clouds, mist, or dust. The corona is the Sun's outer atmosphere. It stretches many thousands of kilometres (miles) beyond the Sun's apparent "surface," gradually converting into solar wind, which travels outward across our solar system. The material in the corona is a tremendously hot yet tenuous plasma. The temperature of the corona is over a million degrees, significantly greater than the surface temperature of the Sun, which is about 5,500 degrees Celsius. The pressure and density in the corona are far lower than in the Earth's atmosphere.

2. What is the effect of solar eclipse on corona ?

Ans: The corona is located above the chromosphere, the Sun's lower atmosphere. The corona and the chromosphere are separated by a relatively thin region known as the transition region. Temperatures in the transition area climb dramatically, from thousands of degrees in the chromosphere to over a million degrees in the corona. Moving upward from the chromosphere to the corona, the density of plasma reduces rapidly across the transition area. The solar atmosphere, including the corona, is generally invisible to us. The Sun's surface is considerably too brilliant to see the corona, which is much fainter. The wispy corona is seen during a total solar eclipse because the Moon shuts out the sun's surface and this is known as the effect of solar eclipse on the corona of the Sun. Astronomers may observe the corona at other times using a special device called a coronagraph.

Comment
Students Also Read