Identify key characteristics of our star,the Sun.

http://www.kidsastronomy.com/our_sun.htm

http://www.nasa.gov/vision/universe/solarsystem/sun_for_kids_main.html

To identify key characteristics of the Sun, we can look at some of its important features:

1. Size and Mass: The Sun is a medium-sized star, about 1.4 million kilometers in diameter. It accounts for about 99.86% of the entire mass of our solar system.

To determine the size and mass of the Sun, scientists use various techniques. One way is through the study of solar oscillations using helioseismology. By observing the oscillations on the Sun's surface, scientists can estimate its size and mass.

2. Temperature and Composition: The Sun's surface temperature is around 5,500 degrees Celsius (9,932 degrees Fahrenheit). At its core, the Sun reaches a staggering temperature of about 15 million degrees Celsius (27 million degrees Fahrenheit).

Scientists determine the Sun's temperature by studying its spectrum. By analyzing the specific wavelengths of light emitted by the Sun, they can uncover the temperature of different layers within it. Spectroscopy is also used to determine the Sun's chemical composition, revealing that it consists mainly of hydrogen (about 73%) and helium (about 25%), with traces of other elements like carbon, nitrogen, and oxygen.

3. Energy Production: The Sun generates its energy through the process of nuclear fusion. In its core, hydrogen atoms combine to form helium, releasing vast amounts of energy in the process. This energy in the form of light and heat radiates into space, and it is what allows life to exist on Earth.

The process of nuclear fusion in the Sun can be understood through theoretical modeling and simulations. By incorporating fundamental principles of physics and nuclear reactions, scientists are able to explain how the Sun's energy is produced.

4. Magnetic Activity: The Sun exhibits various forms of magnetic activity, including solar flares and sunspots. Sunspots are regions of intense magnetic fields that appear as darker patches on the Sun's surface. Solar flares are explosive releases of magnetic energy that can cause geomagnetic disturbances on Earth.

Observations using telescopes, such as the Solar Dynamics Observatory (SDO) and the Solar and Heliospheric Observatory (SOHO), allow scientists to study the Sun's magnetic activity. By analyzing the changes and patterns in the Sun's magnetic field, they can understand its behavior and its impact on space weather.

It's important to note that the knowledge of the Sun's characteristics comes from observations, measurements, and theoretical models developed by scientists over centuries of research. These observations and models have been refined through technological advancements and our continuous exploration of our nearest star.