::Interactive Astronomy::

Sun

The sun is the star of our solar system and it has the largest mass. The sun has 5 regions. Two are on the interior and three are on the exterior of the sun.

The Inner Layers

The stellar interior consists of two parts, they are the core and the convection zone.

Nuclear Fusion: The core is mostly made up of hydrogen and it generates energy as the sun is very massive causing immense gravity and pressure within the inner layers of the sun. The hydrogen core, is thus greatly compressed. As gas heats up upon expanding, the core of the sun is extremely hot. The extreme heat, about 15 million degrees Celsius, stimulates chemical reactions of hydrogen converting into helium. This is done so in the ratio of 4:1. The excess mass is emitted as energy in the form of great amounts of heat and light (gamma rays). The gamma rays bounce off sun matter and eventually get into space. The heat on the other hand is brought out of the convection zone, the second part of the stellar interior. Here, rising steams of gas carry the heat out of the stellar interior. The gas soon condenses and sinks, eventually rising again and bringing out more heat. The sun’s magnetic field is believed to be generated in the lower areas of the convection zone. Nuclear fusion also produces large amounts of neutrinos. Neutrinos are neutrally charged subatomic matter which get dispersed into space and have no mass.

The Outer Layers

Photosphere: "Photosphere" means "light-sphere". It is on this layer where the gamma-rays get passed on into space. The photosphere is actually a layer of gas.

Sunspots: Sunspots are actually just cooler regions on the photosphere, which are <4000C, in comparison with the much hotter surroundings which are >5500C. The sunspots follow a 11-year cycle, where the number of sunspots rises and falls over this period of time.

Chromo sphere & Corona: 10000C. Here, hydrogen clouds (faculae), and hot gases produced by sunspots (flares), are present. Followed by that is the corona, separated from the chromo sphere by the "transition region".

The corona is 1 million Celsius hot. It is the bluish-white layer around the sun which you see during an eclipse. The corona is made up of a rare and immensely electrically-charged gas. The gas is so charged up that its shape and size depends on the strength variations in the sun’s magnetic field. When the magnetic field-lines travel towards the corona and gets deflected back, the corona is more concentrated and visible. When the magnetic lines extend into space, the corona is pale and a small percentage also leaks into space as solar wind.

Solar wind: made up of the "corona gas", and is highly electrically-charged. It disrupts and replenishes the magnetic field of certain planets. Solar eruptions from the sun produce great amounts of solar wind. Solar disturbance resulting in the disruption of magnetospheres are known as "space weather" or "solar storms".

Eruptions within the corona (coronal mass ejections) trigger solar flares within the chromo sphere. Both the coronal mass ejections and solar flares can cause fierce space weather which can disrupt radio waves and blow out electrical circuits on Earth.