Our Sun The Basics



Our Sun A Yellow Dwarf/Photo Astronomy for armatures



Our Sun is not unique in the universe. It is a common middle-sized yellow star which scientists have named Sol. This is why our system of planets is called the Solar System. 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. Indeed these vast nebulae are the birth places of all stars. Over a period of many millions of years, this gas and dust began to fall into a common center under the force of its own gravity.

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

When this happened, the Sun began producing its own light, heat, and energy.

Nuclear fusion is how stars produce their light, heat, and energy. Through this process, they “burn” a fuel known as hydrogen. The result is that they create another type of matter known as helium. However, stars do not burn in the same way that a fire does, because stars are not on fire.

Heat rises, while cooler gas falls. Have you ever noticed that your basement is always much cooler than upstairs. The same laws of physics apply within stars. 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.

On a side note in a recent poll conducted by a leading astronomy magazine found that 55% of adults in the United States don't know that the sun is a typical star, the Sun is known as a yellow dwarf star. This group of stars are relatively small, containing between 80% and 100% the mass of the sun. So the Sun is at the higher end of this group. The official designation is as a G V star.

We will continue the current topic of exploring our sun in the next post, hope you enjoyed today's post and learnt something new.

A Series on the Sun

OUR SUN/PHOTO SPACESTATIONINFO.COM

OK m friends I'm sorry it has been exactly a month since I last posted here, so I am going to get myself motivated and start out a series of posts regarding the sun, not sure how many entries there may be in this series I guess all of us will stand by and see.

The sun is a star which is very closer to earth than any other star and appears very large and bright. Without the Sun's light and heat, there would be no life on Earth. The Sun is a ball of plasma with a mass of about 2×1030 kg. The sun is mainly composed of hydrogen and helium; it contains about 70% of hydrogen, 28% of helium and less than 2% of other metals. The outer atmosphere of sun has a temperature of over 106 K when its visible surface (the photosphere) has a temperature of just 6,000 K. Solar energy is transformed by plants into chemical energy, which is the first step in the food chain for all living things. The Sun has been around for about 4.6 billion years and is expected to keep burning bright for another 5 billion years.

COMPOSITION OF OUR SUN

1. HYDROGEN-73.46%                                                                 6.  NEON-12%
2. HELIUM-24.85%                                                                        7.  NITROGEN-0.09%
3. OXYGEN-0.77%                                                                        8.  SILICON -0.07%
4. CARBON-0.29%                                                                        9.  MAGNESIUM-0.05%
5. IRON-0.16%                                                                             10.  SULFUR-0.04%

Something I found that I thought was interesting was that you always hear astronomers talking about the solar "surface," the Sun is actually s hot that it neither liquid or solid matter anywhere inside it. Moving down through the Sun, one continually encounters ever denser and hotter gases.

The Sun only appears to have a surface because most of it's visible light comes from one specific gas layer. This region which is only about 249 miles thick is called the photosphere. The photosphere is the innermost of the three layers comprising the Sun's atmosphere. Because the upper two layers are transparent to most wavelengths of visible light, we see through them down to the down to the photosphere. We cannot, however, see through the shimmering gases of the photosphere, so everything below the photosphere is called the Sun's interior.

Next entry we will continue with The Sun Part II

How was the moon formed?

Hello everyone and welcome to my first official post of my new astronomy blog, I am hoping I can make this as intresting as I possibly can, and since I am just a novice in astronomy none of which I post should be over anyones head.

The first question I am going to try and cover is how was the moon was created. Currently there are four theroies that astronomers today are kicking around, these four are the capture theory, the cocreation theory, the collision-ejection theory and the last being the fission theory.

The fission theory holds that the Moon was pulled out from a rapidly rotating proto-Earth. This theory does not explain why the Moon has birtually no water incorporated in its rocks, as revealed by the bone-dry samples brouht back by Appollo astronauts. A simple way of stating this is that as the newly formed Earth was rotating at a much faster speed than it does today a blob of material seperated from Earth and became the moon, however if this theory was true there would be traces of water in the rock samples taken from the Moon and not a trace of water has ever been found.

The Capture theory says that the Moon was formed elsewhere in the solar system and then was drawn into orbit about the Earthby gravitatioal forces. However, it is physically very difficult for a planet to capture a large moon. Furthermore, because bodies formed in differnt places have different overall chemical compositions, this theory fails to explain the similar geochemistries of the Moon and the Earth's surfaces.

The cocreation theory proposes that the Earth and the Moon were formed near each other at the same time. However, this theory fails to explain why, compared to the Earth, the Moon has less of the denser elements, such as iron, and why certain types of rocks found on the Moon are not found on Earth.

The fourth theory, now held to be correct by most astronomer is the collision-ejection theory, or large impact theory, it proposes that the newly formed Earth was struck at an angle by a Mars-sized astroid that literally splashed some of the Earth's surface layers into orbitaround the young planet. Evidence from Moon rocks places this event at around 4.5 billion years ago, whithin the first 100 million years of the Earth's existance.

The collision-ejection theory is consistent with many of the known facts about the Moon. For example, rock vaporized by the impact would have been depleted of volatile (easily evaporated) elements and water, leaving the Moon rocks parched, as we know they are. Also, the Moon has very little heavy iron-rich matter because the mateerial had sunk deep into the Earth before the asteroid struck. The material from the Earth that splashed ito orbit and formed the Moon was mostly the lighter rock floating on the Earth's surface. Furthermore, most of the debris from the collision would orbit near the plane of the ecliptic as long as the orbit of the impacting asteroid had been near that plane. Also, the impact of an object large enough to create the Moon could have tipped the Earth's axis of rotation and so inaugurated the seasons we experince today.

I hope any of you (if anyone) who have read this learned something from it, I myself find astronomy very intersting. If you have any questions you would like me to explore please don't hesitate to ask.

Introduction

Hello and welcome to my blog Learning Astronomy, if you made it this far into the various blogs I have running around the Internet than I'm sure you have seen plenty about who I am so I will get right down to why I am writing this blog.

As you probably already know I am 44 years old and currently attending San Diego City College full time on my 9/11 GI Bill. If you are a veteran who separated or retired after 9/11 I suggest you get in touch with your local VA office and check this program out, out of all the previous GI bills in this history of our military this the one with the most benefits, where unlike other GI Bills where you have to pay in money, the only requirement is that you served and got an Honorable Discharge after 9/11.

OK the one thing I believe the only thing in this world that benefits everyone is an education, and I'm not necessarily talking about an education where you have to sit through a boring class or sit in front of a blackboard type program in front of your computer. I myself am a life long learner. It may sound boring to you but even as a child the majority of books I read was something you can learn from, whet er its a book about history, science, math or what ever. Even my wife and sister in law call me data man.

This blog itself is just me wanting to pass on to you what I have learned in my Astronomy class here at San Diego City College, I have found this class very int resting and I believe many are interested in space but don't have the money or time to go to college or for that matter to spend money on books from places like Amazon or Barnes and Noble. So that is my purpose here. Just to pass on what I have learned about astronomy to those who may be interested.

One thing I do want you to know, is that I am very interested in what others think, if you have an opp ion about something I've posted, about this blog in general or even about me, I am open to criticism. If you think what I am doing here is stupid don't be shy tell me so, I may not agree with you but go ahead and bounce it off of me any way.

Well that's enough of my spouting off, I hope that you will enjoy this blog or any others I may have written. I've made quite of few and I know I have some out there that I have forgotten about. If you find one of mine that hasn't been posted in for a month or two or even a year or two let me know so I can go back and look into it.

Thank You for stopping by.