ABOUT THE SUN
The Sun is our nearest star. Its light and heat make life on Earth possible.
When did the Sun form?
Scientists calculate the Sun and solar system formed at approximately the same time, 4.55 billion years ago. This is based on the ages of the oldest objects that we have sampled from our solar system, meteorites.
How did the Sun form?
The solar nebula theory describes how most scientists think the Sun formed. A cloud of hydrogen and helium gas and dust existed in space. It began to compress and eventually gravitational forces pulled the gas and dust together and the cloud collapsed. The collapsing cloud began spinning and flattening into a disk. Much of the material was ...view middle of the document...
Here the energy (radiation) moves randomly from atom to atom, with some of the energy moving toward the Sun's surface.
As energy moves out of the radiative zone, it enters the convective zone. Here the atoms do not pass the energy from particle to particle; the atoms themselves move, carrying the heat with them. The hotter material near the radiative zone rises to the cooler surface of the convective zone. As it reaches the top of the convective zone, it cools and sinks.
The photosphere (“sphere of light”) is the “surface” of the Sun; because the Sun is made of gas, it does not have a solid surface. The photosphere has temperatures that reach about 5800 degrees Kelvin and is the layer that releases most of the light that reaches Earth.
The surface of the Sun has continuously changing dark regions or sunspots. The spots are dark because they are cooler than the surrounding gas (about 3230 degrees Celsius). Sunspots can persist for an hour to several months. The number of sunspots increases and decreases in an 11-year cycle, the solar cycle.
The photosphere and sadanslyng, unspots can be viewed safely with special solar telescopes, but not directly with the human eye!
The chromosphere (“sphere of color”) is a 2000-kilometer-thick layer of gas that reaches temperatures between 6000 and 50,000 degrees Celsius. Most of the energy from the chromosphere is released as red light, which means that the chromosphere can be viewed with special telescopes that filter out the other wavelengths. The chromosphere is dynamic; convection cells swirl the surface, and material shoots off the surface as flame-like features.
The corona is a thin outer layer of the Sun that is seen during a solar eclipse. The corona emits energy at many different wave lengths. Loops and arches of matter are often seen extending out from the corona along lines of the Sun's magnetic field. This material flows away from the Sun as the solar wind. Some of the particles reach Earth's atmosphere and interact with atmospheric particles to create the aurora.
What is the Sun made of?
While approximately 60 different elements make up the Sun, hydrogen accounts for about 92% of the atoms (almost three-fourths of the...