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When the photo was shown on CNN, [See Image1] hundreds of calls came in from people reporting — they could see a face in the cloud. When the color of the photo was adjusted, a large human form seemed to appear within the cloud. [See Image2]
Image 1: Simulacrum in Eagle Nebula-
- Picture of the Day – The Eagle Has Risen (spacefellowship.com)
- A star wrapped in the beautiful colors of the nebula that birthed it [Space Porn] (io9.com)
- The Pelican Nebula: Facts and FAQs (brighthub.com)
What does “The Solar System” mean?
The Solar System means the system of the Sun. All bodies under the gravitational influence of our local star, the Sun, together with the Sun, form the Solar System.
Bodies? What kind of bodies?
•The largest bodies, orbiting the Sun, including Earth are called planets.
•Often smaller cool bodies called satellites or moons, orbit a planet.
•Bodies smaller than than the planets that orbit the sun are classed as
asteroids if they are rocky or metallic, comets if they are mostly ice and dust, and meteoroids if they are very small. Most comets release gases as they near the heat of sun, producing a luminous cloud called coma & often a long tail. A meteoroid that burns in Earth’s atmosphere is a meteor, while one that reaches Earth without burning completely becomes a meteorite.
• After the exclusion of Pluto from the planet category, a new category is formed: Dwarf Planet.
Elements of Solar System:
Stars: (1) The Sun
Planets: (8) Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
Dwarf Planets: (4) Pluto, Charon, Eris, Ceres- along with the numerous satellites that travels around most of planets.
In this article, I shall discuss about the Sun only. Further bodies will be discussed in Part IV & V. While, next Part i.e. PART III, will bring you into the interior of Sun. I suggest you again to read Part I of this Series.
SnapShots & facts about the Sun:
• Sun is one of more than 100 billion stars in the giant spiral galaxy called the Milky Way.
• Sun is the center of the solar system. Its mass is about 740 times as much as that of all the planets combined.
• It continuously gives off energy in several forms- visible light; invisible infrared, ultra-violet, X-rays and γ -rays, cosmic rays, radio waves and plasma.
•The Sun generally move in almost circular orbits around the galactic center at an average speed of about 250 km per second.
•It takes 250 million years to complete one revolution round the center. This period is called a Cosmic Year.
•It’s energy is generated by nuclear fusion in its interior. It is calculated that the Sun consumes about 4million tonnes of hydrogen every second. At this rate, it is expected to burn out its stock of hydrogen in about 5billion years and turn into a red giant.
Absolute Visual Magnitude: 4.75
Diameter: 1,384,000 km
Time of one Rotation as seen from the Earth: 25.38days (at equator) to 33days (at poles).
Other Elements 2.5%
Age: 4.5 billion years aprox.
Expected lifetime: 10 billion years aprox.
Mean distance from Earth 8.2 light seconds i.e. Aprox. 150 million km.
What is it?
There are many millions of stars in the sky. In the whole heavens, fewer than 6000 stars are bright enough to be visible and at any one time, less than 2500 stars are visible above the horizon.
Stars account for 98% of the matter in a galaxy. The rest of 2% consists of interstellar or galactic gas & dust in a very attenuated form. The normal density of interstellar gas throughout the galaxy is about one tenth of a hydrogen atome per cm³ volume. Stars tend to form groups.
What I shall discuss here?
There are many types of stars in the universe having different name & definitions. I’ll discuss a few of them!
Major kinds of Stars according to numbers
• Lone Stars :These are alone and going on their own. Lone stars are exception in the Universe.
These donot follow up the condition to be in galaxy. And this is the difference between it & Single stars.
•Single Stars These are found in galaxy & are single (for example Our Sun). These do not number more than 25% of Stellar (Star) Population.
•Binary Stars or Double Stars These exist as couples of stars (e.g., Antares in Scorpio is actually two stars) and they are some 33% of stellar population.
The rest are •Multiple Stars (e.g., Capella & Alpha Centuri comprize 3 stars each, while Castor consists of 6 stars).
Note that, stars which appear single to the naked eyes are sometimes double stars. There are two stars revolving around a common center of gravity. They are also found in orbital motion round each other, in periods varying from about one year to many thousands of years.
Vivid types of Stars according to their nature
When the hydrogen, the main element in a star, is depleted, its outer regions swell and redden. This is the first sign of age. Such stars are called Red Giants.
Our Star, the Sun, is expected to turn into a red giant in another 5 billion years. Red giants are dying stars that has expanded greatly from its original size and gives off red light. They have gigantic dimensions.
It is the blackened corpse of a star. Ultimately it disappears into the blackness of the space.
It is a tiny, dense, hot star, representing a late stage in the life of a star. The matter in it is so incredibly dense that a single teaspoonful of it would weigh several tonnes.
These are huge stars, with all their hydrogen fuel used up in their core, but continue to expand hundred of times bigger than its original size before they finally die.
Novae & SuperNovae
These are kind of stars, whose brightness increases suddenly by 10 to 20 times are more and then fades gradually into normal brightness. The sudden increase in brightness is attributed to a partial or outright explosion. In Nova, it seems that only the outer shell explodes, whereas in SuperNova the entire star explodes.
There are stars that show varying degrees of luminosity.
These are variable stars and are powerful quasi stellar sources of radio radiations.
These are also variable stars which emit regular pulses of electro-magnetic waves of very short duration.
© Gaurav Happy Tiwari, 2011
A typical galaxy contains much more matter than what we can actually see. In fact, the visible portion of a galaxy represents only about 5 to 10% of total mass of the galaxy. Many studies lead us to define the conclusion that the Universe abounds in matter that we cannot see. This unseen matter is called Dark Matter because either it does not emit light or its light emission is too dim for us to detect.
Normal matter, such as STARS, PLANETS, DUST and MOLECULES , is often called Baryonic Matter because its mass is primarily due to the combined mass of the protons and neutrons, which are combinedly called Baryons, it contains. The mass of electrons is neglected because the mass of an electron is so small relative to the mass of a proton or neutron. Some of the normal matter such as burned out stars and dim interstellar gas, is part of the dark matter in a galaxy.
However, according to various calculations, this dark normal matter is only a small part of the total dark matter. The rest is called Non Baryonic Dark Matter because it does not contain proton and neutrons. What it contains? We know only one member of this type of dark matter…..the neutrinos.