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So are you ready to enter into the Sun?
Corona is the outermost part of the sun & you may see it when Full Solar Eclipses occur. The temperature of corona is about 2.7million°C, which is hot enough to emit ultravoilet and X-rays. The corona extends millions of kilometers into space above the photosphere and is very hot- millions of degree celcius.
In a solar eclipse, a red circle around the outside of the Sun can be seen sometime. This is the chromosphere. The chromosphere is made up of the gases that extend away from the photosphere.Chromosphere is of red color, caused by the abundance of hydrogen. It has a greater (than Photosphere) temperature of about 10000°C. The Chromosphere merges into Corona & Photosphere.
The photosphere is the zone from where the sunlight we see is emitted. The photosphere is a layer of low pressure gasses surrounding the envelope. It is 400 km thick, with a temperature of 4500°C to 6000°C.
The innermost layer of the sun is the core with a density of 160g/cm³ (10 times that of lead). The core might be expected to be solid. However, the core’s temperature of 15 million°C keeps it in a gaseous state. In the core, fusion reactions produce energy in the form of γ rays and neutrinos.
From the photosphere of the sun to the chromosphere and to the Corona , the temperature increases, while the same procedure follows up from the photosphere to the core of the sun (I mean temperature increases). Thus you may say in other words that the Photosphere is the COOLEST PLACE in the sun.
Spots in Sun? — SunSpots
The sun has enormous organized magnetic fields that reach from pole to pole. Loops of the magnetic field oppose convection in the convective envelope and stop the flow of energy to the surface. This results in cool spots (i.e. SUNSPOTS) at the surface which produce less light than the warmer part.
Sunspots are dark spots on the photosphere, typically with the same diameter as the Earth.
Sunspots have cooler temperatures than the photosphere. So our thoughts again changes here, that photosphere is the coolest part on the Sun— Now it is the sunspots.
The center of a spot is called the umbra, looks dark gray if heavily filtered & is only 4200°C (as compared to the photosphere at 6000°C).
Penumbra is the portion around the umbra, which looks lighter gray (if filtered).
Sunspots come in cycles, increasing sharply (in numbers) & then decreasing sharply. The period of this solar cycle is about eleven years. The largest spot ever measured (APRIL 1974) covered 18130 million km² i.e., 0.7% of the Sun’s visible surface. The life periods of these spots also vary—from a few hours to many weeks.
It is an effect of sunlight.
Polar Auroras are two auroras, the Aurora Borealis or Nothern Lights and the Aurora Australis or Southern Lights. These are lights that sweep across the sky in waves or streamers or folds. They are very often multi-colored and provide one of the finest spectacles in nature. They occur in Arctic and the Antarctic regions respectively. But the Northern lights can be seen as far south as New Orleans in America and the Southern lights as far north as Australia.
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