Introductory Astronomy: Sun


You also may be interested in my post about hydrogen bomb with pictures and videos.

Sun is the Center

Some time ago I wrote about the difference between stars and planets, read that post first if you haven’t yet. Sun is the closest star to Earth. Almost all the energy we use is a transformed Sun energy. Food we eat is the Sun energy, gas we burn is the Sun energy. Our star is a pure energy. It is huge comparing to our planet and it is the center of our Solar system.

Sun is really huge and heavy comparing to planets in solar system. Thats why it is the center. Image from: www.vjkrishna.com

Sun is really huge and heavy comparing to planets in solar system. That's why it is the center. Image from: http://www.vjkrishna.com

Where Does Sun Get It’s Energy From?

Sun mass creates a tremendous pressure in its core pressure is so high that hydrogen atoms are squeezed and transformed to helium. During this transformation a lot of energy is released and this is the energy which we see as a light, which warms us and which feeds all the plants on our planet. Hydrogen -> helium transformation is called a thermonuclear reaction. This is the kind of reaction we want to be able to reproduce on Earth, but failed so far. Well we did reproduce it in the form of hydrogen bomb, but that’s not what we really would like to have.

Hydrogen bomd destruction comes from the same reaction which powers our Sun. Image from: ovalscream.wordpress.com

Hydrogen bomb destruction comes from the same reaction which powers our Sun. Click for bigger version. Image from: ovalscream.wordpress.com

How Ideal Is The Sun?

In human history Sun was always associated with some God. It was always some kind of ideal object, that’s why it was so difficult in the beginning to accept that it has black spots on it’s surface. Just think about it: black spots on a god’s surface. Our mind passed a long way in understanding the world, something you take for granted today some time ago was a big deal.

Ideal Sun appeared to have dark spots. Image credit NOAA.

"Ideal" Sun appeared to have dark spots. Image credit NOAA.

In telescope Sun is not even smooth like it may look for a naked eye, it is granulated. They say granules come from the convection flows (hot masses rise to the top, cold ones sink to bottom).

Sun surface is not even smooth, its granular. Image credit: NASA.

Sun "surface" is not even smooth, it's granular. Image credit: NASA.

And one more thing defeats the “ideal & smooth round” Sun image — solar prominence. Our star has a very strong magnetic field and consists of plasma (it’s not the sci fi gun, it’s a state of material, for example the flame in your campfire is plasma too, basically plasma is a very hot gas).   Sometimes plasma is ejected from the Sun (it’s a constant super hydrogen bomb explosion inside of it, remember?) ejected mass often “hangs” on a magnetic string, because plasma consists of charged particles which interact with Sun’s magnetic field.

Sun plasma ejections are very often hang on magnetic strings, thats where their tricky shape comes from. Image credit: NASA

Sun plasma ejections (top right on this photo) are very often "hang" on magnetic strings, that's where their tricky shape comes from. Image credit: NASA

Sun Cycle

Many processes astronomy deals with happen in cycles. Earth has seasons, Moon has phases and Sun has a cycle too. It lasts about 11.2 years and on the peak of activity Sun shines about 1% brighter comparing to the low activity period. This cycle may be much more important than we currently think, because some studies found connection between solar cycle and global temperature, human health or even prices of wheat :-)

How Do We Study Sun?

Little update: I came across nice video from NASA with a lot of information about solar monitoring satellites. The cool thing is that they use real 3D model with real satellites and real time scale to demonstrate everything. You can see how satellites use planets to alter their orbits and stuff like that. Shortly speaking — video worth watching.

Read my previous article about Moon if you haven’t yet.

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