Sun
From Wikipedia, the free encyclopedia
The Sun is the star and the largest object in our solar system. The planets in our solar system move around the sun in orbits. Our sun can be seen in the sky in the day time. It is a large yellow ball. The sun is basically a very large ball of non-stop explosions. These explosions give off a lot of energy. Even though the sun is very far from the earth, we still feel this energy. The Sun is so bright that it can hurt to look at it and can damage your eyesight so never stare at the sun and never use binoculars or a telescope to look at it. The Sun makes light, heat and solar wind. Solar wind moves around the earth outside our atmosphere. It is made of small particles that fly away from the sun. The sun is the main source of energy for life on Earth.
The Sun is at the middle of our solar system. Each planet travels in a more-or-less round orbit with the sun in the center. Each planet orbits at a different distance from the sun. The orbits of the planets are not circles. They are curves called ellipses. The planets closest to the Sun get more heat. Planets further away are colder.
All life on our planet needs the light energy that comes from our Sun. Plants use solar energy as food so they can grow. Solar energy and a process called photosynthesis cause the green color of many leaves and plants.
In the center of the Sun, in its core, great heat and pressure combine hydrogen gas into helium gas which produces large amounts of energy. This is called nuclear fusion.
People can look at the Sun if they use special lenses that make it safe. When they do this, darker spots are sometimes seen on the surface of the Sun; these spots are called sunspots. The number of sunspots on the Sun gets bigger and then smaller in a cycle of about 11 years. The number affects the weather on Earth and can also affect electronics.
Contents |
[change] How the Sun was born
Scientists think that the Sun was born from a very large cloud of dust and small bits of ice 4.6 billion years ago. At the center of that huge cloud, some of the material started to build up into a ball. Once this ball got big enough, reactions inside it caused that ball to shine.
At that point, the Sun blew away all the rest of the cloud from itself, and the planets formed from the rest of this cloud
[change] How the Sun works
At its core, or very center, hydrogen atoms are collided together to form helium. This process is called nuclear fusion. These helium atoms then travel from the core to the surface of the sun, called the photosphere, where they release their energy. Helium atoms can take thousands of years to reach the Sun's surface because other atoms get in their way.
[change] Features of the Sun
[change] Sunspots
If you look at the sun through a special telescope, the first things you will notice are sunspots; dark areas on the Sun. These areas are caused by the sun's magnetic field. The sunspots only look dark because the rest of the Sun is very bright.
[change] Sunspot cycle
This is a cycle of 11 years, and every 11 years, there are more sunspots on the Sun than in the past or future years. Between these 11 years, sunspots may decrease in number. This cycle has been around since about the 1700s; before that was the Maunder Minimum, a few hundred years where there were very few sunspots. Astronomers don't know what caused this.
[change] Prominences
Some space telescopes, like the ones that orbit the sun have seen huge arches that extend from the sun. These are called solar prominences. Solar prominences come in many different shapes and sizes; some of them are so large that the Earth could fit inside of them, and there are a few shaped like hands!
[change] Layers of the Sun
There are a few different layers that make up the atmosphere of the sun.
[change] Photosphere
[change] Coronosphere
This is the layer of which the sun's rays "shine". It can be best seen during a solar eclipse
[change] Solar eclipses
Sometimes, the Sun "disappears" from the sky, and all that people see is a black but shining ball. This is because the Moon has moved right in front of the Sun and blocks almost all of its light. These happen almost every year, and very similar solar eclipses happen every 18 years, 11.3 days; a period called the Saros.
[change] The fate of the Sun
Scientists called astrophysicists say our Sun is a main sequence star in the middle of its life. In about another 4-5 billion years, they think it will get bigger and become a red giant star. The sun would be up to 250 times its current size, as big as 1.4 AU. Earth's fate is still a bit of a mystery. Previous calculations show due to the stellar wind, which drops 30% of the sun's mass, Earth could escape to a higher orbit. But a newer study shows that due to the tidal forces, Earth would possibly vanish itself while the sun continues to get bigger, although the sun will lose mass. Anyway, Earth's ocean and air would long have worn out, even if the sun is still on its main sequence stage. After the Sun reaches a point where it can no longer get bigger, the Sun will literally explode, but not like a supernova, but rather, it will expand rapidly and lose its layers, forming a planetary nebula. Eventually the sun will shrink into a white dwarf, and over several hundred billion, even trillion years (100,000,000,000 to 1,000,000,000,000 years), fade to a black dwarf.
|
|
|---|
 |
| The Sun · Mercury · Venus · Earth · Mars · Ceres · Jupiter · Saturn · Uranus · Neptune · Pluto · Haumea · Makemake · Eris |
| See also: List of solar system objects |
