Sun

The sun is the largest celestial body in our solar system. The average distance of the sun from the Earth is 149,597,870 kilometers. Its radius is about 432,5000 miles. In other words it is about 109.3 times more than earth's. The Sunís volume is about 1.3 million times the volume of the Earth. Also, the mass of the Sun is about 333,4000 times greater than the mass of earth. The Sun is also a very bright star. The Surface temperature of the sun is about 10,000 F. The intense heat of the sunrays can destroy the retinal cells, which causes blindness.

Sun

The sun is the largest celestial body in the solar system. The sun has many gods that represent it; there is the Roman god, Apollo, Helios (is another name for Apollo) and the Egyptian god, Ra. Apollo was the twin of Artemis (Greek) or Diana (Roman) and the son of Jupiter. His symbol represents the egg of creation. Apollo had many talents especially for music. One myth states Mercury had stolen Apollo's cows, so in return, Mercury traded Apollo his lyre. He later traded Mercury a musical pipe for a staff. He has a throne on Olympus, which is the home of the gods. The sun in astrology represents the force of life; it focuses on you, what you are and what you do. The Laurel tree, the dolphin, crow and many other animals are sacred to Apollo.

Sun Facts Sheet:

Mass 1.989 x 1030 kgMean density 1410 kg/m3 (about 25% of the earth density

Interior: about 70% hydrogen and 28% helium by mass everything else ("metals") amounts to less than 2%.

Core Temp: 15.6 million Kelvin

Atmosphere: photosphere, is at a temperature of about 5800 K

A small region known as the chromosphere lies above the photosphere

the corona, extends millions of kilometers into space but is visible only during a total solar eclipse (left). Temperatures in the corona are over 1,000,000 K

Sun

diameter: 1,390,000 km. mass: 1.989e30 kg temperature: 5800 K (surface) 15,600,000 K (core)

The Sun is, at present, about 70% hydrogen and 28% helium by mass everything else ("metals") amounts to less than 2%. This changes slowly over time as the Sun converts hydrogen to helium in its core.

The outer layers of the Sun exhibit differential rotation: at the equator the surface rotates once every 25.4 days; near the poles it's as much as 36 days. This odd behavior is due to the fact that the Sun is not a solid body like the Earth. Similar effects are seen in the gas planets. The differential rotation extends considerably down into the interior of the Sun but the core of the Sun rotates as a solid body. Conditions at the Sun's core (approximately the inner 25% of its radius) are extreme. The temperature is 15.6 million Kelvin and the pressure is 250 billion atmospheres. At the center of the core the Sun's density is more than 150 times that of water.

The Sun's energy output (3.86e33 ergs/second or 386 billion billion megawatts) is produced by nuclear fusion reactions. Each second about 700,000,000 tons of hydrogen are converted to about 695,000,000 tons of helium and 5,000,000 tons (=3.86e33 ergs) of energy in the form of gamma rays. As it travels out toward the surface, the energy is continuously absorbed and re-emitted at lower and lower temperatures so that by the time it reaches the surface, it is primarily visible light. For the last 20% of the way to the surface the energy is carried more by convection than by radiation. The surface of the Sun, called the photosphere, is at a temperature of about 5800 K. Sunspots are "cool" regions, only 3800 K (they look dark only by comparison with the surrounding regions). Sunspots can be very large, as much as 50,000 km in diameter. Sunspots are caused by complicated and not very well understood interactions with the Sun's magnetic field. A small region known as the chromosphere lies above the photosphere. The highly rarefied region above the chromosphere, called the corona, extends millions of kilometers into space but is visible only during a total solar eclipse (left). Temperatures in the corona are over 1,000,000 K.

The visible solar atmosphere consists of three regions: the photosphere, the chromosphere, and the solar corona. Most of the visible (white) light comes from the photosphere, this is the part of the Sun we actually see. The chromosphere and corona also emit white light, and can be seen when the light from the photosphere is blocked out, as occurs in a solar eclipse. The sun emits electromagnetic radiation at many other wavelengths as well. Different types of radiation (such as radio, ultraviolet, X-rays, and gamma rays) originate from different parts of the sun. Scientists use special instruments to detect this radiation and study different parts of the solar atmosphere. The solar atmosphere is so hot that the gas is primarily in a plasma state: electrons are no longer bound to atomic nuclei, and the gas is made up of charged particles (mostly protons and electrons). In this charged state, the solar atmosphere is greatly influenced by the strong solar magnetic fields that thread through it. These magnetic fields, and the outer solar atmosphere (the corona) extend out into interplanetary space as part of the solar wind.

Atmosphere

To understand how our Sun works, it helps to imagine that the interior of the Sun is made up of different layers, one inside the other. The innermost layer, the solar core, is the region where the energy of the Sun is produced. This energy travels through the next layer of the solar interior, called the radiation zone, and eventually reaches the convection zone, where energy is transferred mainly by the overturning of solar gases. This convection produces an everchanging pattern of cells on the surface of the sun. Direct observations inside the Sun are not possible, however some diagnostics exist that allow us to study the Sun's interior.

Interior

Structure

Core (200,000 km, 15,000,000 K)

Radiation Zone (200,000 – 500,000 km, 7,000,000 K)

Convection Zone (500,000 – 700,000 km, 2,000,000 K)

Photosphere (700,000 – 700,500 km, 5800 K)

Chromosphere (700,500 – 702,000 km, 4500 K)

Transition zone (702,000 – 710,500 km, 8000 K)

Corona

Sun

Luminosity – the rate at which energy is generated by the surface of the sun.

Power – the rate at which energy is generated or consumed.

P = Energy/time

MKS units: J/sec which is called a Watt (W)

The luminosity of the sun is about 4 x 1026 W

Sun

Note:

Solar constant is defined to be the power per square meter received at the surface of the earth = 1400 W/m2