The sun
20
-
Upload
jrooz-review-center -
Category
Education
-
view
240 -
download
0
Transcript of The sun
This star provides all the energy necessary to sustain life on Earth.
Our Sun is not unique in the universe. It is a common middle-sized yellow star which scientists have named Sol.
There are trillions of other stars in the Universe just like it. Many of these stars have their own systems of planets, moons, asteroids, and comets.
The Sun was born in a vast cloud of gas and dust around 5 billion years ago. The nebulae are the birth places of all stars.
At the center, an ever growing body of mass was forming. As matter falls inward, it generates a tremendous amount of heat and pressure. As it grew, the baby Sun became hotter and hotter. Eventually when it reached a temperature of around 1 million degrees, its core ignited, causing it to begin nuclear fusion.
Nuclear fusion ishow stars
producetheir light,heat, and energy.Through thisprocess, they“burn” a fuelknown ashydrogen. Theresult is that theycreate anothertype of matterknown as
helium.
Heat rises, while cooler gas falls. Because heat rises, while cooler gases fall, the gas within stars is constantly rising and falling. This creates massive streams of circular motion within the star. This is called convection.
As the gases near the core of the Sun are heated, they begin to rise towards the surface. As they do so, they cool somewhat. Eventually, they become cool enough that they begin to sink back down towards the core. It can take an atom millions of years to complete one complete cycle around a convection stream.
These are areas which are slightly cooler. However, sun spots are still very hot. It appearsslightly dark in color because the area is coolercompared to its surrounding areas.
Sun spots come and go on a regular basis.
At times there are very few if any sun spots. Other times there are far more.
They generally increase in intensity and then decrease over a period of 11 years.
This 11 year cycle is known as the Saros Cycle.
During periods of high solar activity, the Sun commonly releases massive amounts of gas and plasma into its atmosphere.
On occasion these more powerful flares
can even cause satellites on orbiting the Earth to malfunction.
They can also interact with the Earth's magnetic field to create impressive and beautiful light shows known as the Northern and Southern lights.
As the Sun burns hydrogen at its core, it releases vast amounts of atomic particles, or pieces of atoms into outer space. These atomic particles, along with the Sun's radiation create a sort of wind, known as the solar wind.
This wind blows particles outward in all directions from the Sun.
The surface of the Sun is much cooler than its atmosphere.
The Sun's surface is a warm 6,000 degrees Celsius.
This is the same temperature as the Earth's core.
The sun can stay in this balanced state for a total of about 10 billion years.
Given the sun's age as about 4.6 billion years, one can assume we have 5 billion years or so to go.
Eventually most of the hydrogen in the center will get used up, and the sun will enter a dying phase.
