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| SOL | MERCURY | VENUS | EARTH | METEORS | MOON | MARS | ASTEROIDS | JUPITER | SATURN | URANUS | NEPTUNE | PLUTO | COMETS |
| Current Solar Flare (X-ray) activity : |
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| (Updated every ten minutes from the NOAA Space Environment Center through n3kl.org.) | |
The conflagration at the heart of our solar system is a star named Sol. It is a star like all the other stars in the night sky, except that it's a lot closer, and a lot more important, at least to us. It holds our solar system together, and gives it the sustenance of life. Without Sol, there would be no solar system, no Earth, and no us.
In the vacuum of space, particles have a tendency to congregate. There is a mutual attraction between quantum particles similar to the gravity of larger objects, that results in the formation of huge clouds of gas and dust, like the Great Orion Nebula, and it is inside these clouds that stars are born.
When one of these clouds is large enough, and dense enough, gravity takes over from quantum attraction, and begins to pull everything toward its center. Eventually, the center of the cloud becomes so dense that particles collide, creating friction, which creates heat, and the cloud begins to heat up. This process continues for a very long time, millions of years in fact, until eventually the center of the cloud has become so dense and so hot that hydrogen atoms begin to fuse into helium atoms, a process known as nuclear fusion. This is the same process involved with hydrogen bombs, and as we saw at Hiroshima and Nagasaki, it is a process that releases staggering amounts of energy. This powerful energy inside the cloud builds, and moves outward, and begins to counteract the inward pull of gravity. When nuclear fusion is strong enough to stop the inward energy of gravity, a precarious balance is reached between two of the most powerful known forces in the universe, and a star is born, much as depicted in the NASA artist rendering below. (click on image to enlarge)
The interior of a star is a very busy and crowded place. When photons/waves of electromagnetic energy are produced by fusion in the center of the star, it can take over a million years, bouncing around inside the star like microwaves trapped inside a microwave oven, before they finally make their way to the surface of the star and escape into space as solar radiation.
For the next few billion years, the star continues happily burning away as a hot young star, fusing hydrogen into helium, like millions of nuclear bombs going off simultaneously, over and over. But eventually, after a few billion years, the supply of hydrogen begins to run out, and the star begins to die. For our Sun, this will happen in about five billion years from now. It will slowly cool and change color. And as the outward pressure produced by fusion lessens, gravity begins to get the upper hand again, and it will begin to contract. What happens next depends on the size of the star.
For a small or average star like our Sun, there is not enough gravity to hold on to its cooler, outer layers, and while its core compresses, its outer layers expand outwards, turning the star into a red giant. Eventually the outer layers dissipate, leaving behind the very small, but still very hot core of the star, and it is now known as a white dwarf. With no fuel to sustain it, the white dwarf slowly cools and fades. But its extreme density means that its gravity is still a mighty force to be reckoned with, and can have a profound effect on objects in its vicinity. Ninety seven percent of all the stars in the Universe, including our Sun, will end their lives in this manner.
For stars more than 8 times the mass of our Sun, the amount of material being pulled into its core is too much to handle. The core becomes so hot and so dense, atoms are fused into more complex elements such as carbon, oxygen, nitrogen, magnesium, copper, gold and lead. Finally, the core of the star is compressed to the point that it ends its life in the mother of all explosions: a supernova. This explosion is so powerful it produces more light than an entire galaxy of billions of stars, and can be seen millions of light years away. What is left is a small, super dense, rapidly spinning remnant called a neutron star, or pulsar, surrounded by an expanding halo of gas and dust containing all the new complex elements formed by the dying star, seeding the cosmos with the building blocks of life. For this is where all the complex elements in the universe come from, the explosive death of a super massive star. All the complex atoms that make up all the planets and moons and rocks and trees and you and me, were made inside a star.
Below is a photo of the Crab Nebula in the constellation Taurus. It is the remnant of a supernova that exploded almost a thousand years ago. (click on image to enlarge)
Occasionally a star is so massive that when it uses up its fuel and begins to collapse, the heat and pressure in its core are so great they transcend the very laws of physics, and something magical happens - it disappears! The extreme density creates a gravitational field so intense that nothing within a certain distance (called the event horizon) can escape, including the fastest thing in the Universe: light. All that is left is a black hole in space, which appropriately enough is called a Black Hole. But although they are invisible, they are the most powerful objects in the Universe. Powerful enough to pull in stars thousands of light years away, and form galaxies. We now know that virtually all galaxies have black holes at their center. Below is a NASA diagram showing the wildly spinning vortices and energy fields surrounding a Black Hole.
The classification of stars is illustrated by the H-R diagram below, named for the two astronomers, Hertzsprung and Russell, who designed it. Each star is given a letter, designating its spectral class, followed by a number from 1 to 9, specifying where it falls within that class. Our Sun is a G2 yellow main sequence star, with a surface temperature of almost 6,000 degrees. A star with a spectral class of G3 would be slightly cooler.
A star's spectral class is determined by analyzing its spectrum, the specific wave qualities of the light it emits. Every star produces a unique spectrum, as individual as a fingerprint, from which modern technology is able to gleen a great deal of information, and that is no small thing. Stars are the engines that run the cosmos. The more we know about stars, the more we know about the cosmos.
Almost all stars follow the main sequence path (or close to it) for almost their entire lives. It is usually only when stars are very young or very old that they stray any distance from this path.
The Sun is one million miles in diameter. A million Earths could fit inside it, with room to spare. It is 93 million miles away from us, a distance also known as one astronomical unit (AU), one more tool to try and make sense of the vast distances in space. The Sun is so far away that its light - traveling 186,000 miles per second, takes a full eight minutes to reach us.
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