The Sun it's atmosphere and internal structure

The Sun

# Age: 4.6 billion years.
# Diameter: 1.39 million km.
# Temperature: 6000 °C on surface and 16 million °C in core.
# Density: 1.41 times that of water.
# Density of water = 999.97 kg/m³ = ~ 1 g/cm3;
# Density of Iron = 7870 kg/m³.

# That implies Iron is = 7.87 times denser than water. In comparison, earth is about 5.5 times denser than water.

# The surface gravity of the Sun is 274 m/s2 (28 times the gravity of the Earth).
Comparatively, the surface gravity of the earth and moon are 9.8 m/s2 and 1.62 m/s2 respectively.
# Period of rotation: 25 days 9 hrs.
# Speed of rotation: 7179.73 km/hrs. Comparatively, earth’s rotational velocity is 1675Km/hrs.
# Sun is equivalent to 3,32,900 Earth masses.
Stars like Sun are rare in Milky Way galaxy, whereas substantially dimmer and cooler stars, known as red dwarfs, are common.

# The Sun is composed of roughly 98% hydrogen and helium.

# The vast majority of the solar system’s mass is in the Sun (~99.8%), with most of the remaining mass contained in Jupiter and Saturn.

# Although the Sun dominates the system by mass, it accounts for only about 2% of the angular momentum due to the differential rotation within the gaseous Sun.

# Sun is rotating in counter-clockwise direction (when viewed from a long way above Earth’s north pole).

# Those objects closer to the Sun, which are more affected by heat and light pressure, are composed of elements with high melting points.

# Objects farther from the Sun are composed largely of materials with lower melting points.


2) The Sun’s Internal Structure and Atmosphere


# The solar interior, from the inside out, is made up of the core, radiative zone and the convective zone.

# The solar atmosphere above that consists of the photosphere, chromosphere, and the corona (solar wind is an outflow of gas from the corona).

Photosphere

# The photosphere is the bright outer layer of the Sun that emits most of the radiation.

# The photosphere is an extremely uneven surface.

# The effective temperature on the outer side of the photosphere is 6000°C.

Chromosphere

# Just above the photosphere is the chromosphere.

# It is relatively a thin layer of burning gases.
The chromosphere is a bit cooler — 4,320 ֯C.

Sunspot

# A dark patch on the surface of the Sun is known as a sunspot.

# Sunspots appear as dark areas because they are about 500-1500°C cooler than the surrounding chromosphere.

# The individual sunspot has a lifetime ranging from a few days to a few months.
Each spot has a black centre or umbra, and a lighter region or penumbra, surrounding it.
It has been suggested that the Sun is 1% cooler when it has no sunspot and that this variation in solar radiation might affect the climates of the Earth.

Solar Wind
# The solar wind is a stream of energised, charged particles, primarily electrons and protons, flowing outward from the Sun at speeds as high as 900 km/s and at a temperature of 1 million degrees (Celsius).

# It is made of plasma (ionised atoms).