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What is the Universe?
Over the ages man has developed various concepts about the universe. Ancient astronomers and mathematicians believed the universe to be centred around a motionless earth. This concept was then changed by Copernicus who gave the theory of the universe being centred around the Sun. It was in the 19th century that the perception of the universe was further widened. British astronomer Herschel came ont with the view that the Solar system was part of a much bigger star system, namely the Galaxy. This vision was again expanded in the 20th century by American astronomer Hubble, who contented, that the universe consisted of millions of galaxies.
According to modern astronomy the universe consists of everything that is in the cosmos and that can affect us by means of physical forces. This therefore excludes anything that is physically undetectable.
How did the universe begin?
There are many theories regarding the beginning of the universe. The pulsating theory says that the universe cyclically spreads and contracts, cach cycle taking billions of years. One of the most commonly accepted theories in modern times is the 'Big bang theory. According to this theory the universe began some 10-13 thousand million years ago with the explosion of an unimaginably dense ball of matter or primeval atom and has been expanding since then.
There is no satisfactory answer as to why the Big Bang occurred, but the theory is supported by the evidence that the universe is constantly expanding.
Will the Sun ever burn out?
The great fire of the Sun has burned non-stop for around 5000 million years and there is no apparent sign of it going out. We on Earth soak up only about one-hundred-millionth of the Sun's vast energy. The rest of its awesome output of heat and light vanishes beyond the planets and into space.
The Sun is composed of almost 75 percent hydrogen and 25 percent helium, plus much smaller amounts of oxygen, carbon, neon, nitrogen, magnesium, iron and silicon. It is known as a main sequence star, one that shines by burning hydrogen.
At the Sun's heart, the hydrogen was once compressed with such force that it started a nuclear reaction. In this giant furnace, the hydrogen is converted by nuclear fusion into another combustible gas, helium, in a reaction similar to that in an H- bomb. Thus, the Sun is both burning fuel and creating it. As the hydrogen store diminishes, its stock of helium grows. The light and heat now coming from the Sun were actually produced in its core many million of years ago.
The helium that the Sun produces is only about
92.3 percent of the hydrogen it burns. The other 7.7 percent is in several forms of energy, mainly heat, light and X-rays. This loss of hydrogen is slight when compared to the Sun's enormous bulk. Even though it is composed of light gas, the Sun weighs some 30000 times as much as the Earth. The Sun loses about 4 million tonnes of matter every second.
Scientists predict that the Sun has enough hydrogen to keep the fire going for another 5000 million years, about as long as it has already burned.
Over the ages man has developed various concepts about the universe. Ancient astronomers and mathematicians believed the universe to be centred around a motionless earth. This concept was then changed by Copernicus who gave the theory of the universe being centred around the Sun. It was in the 19th century that the perception of the universe was further widened. British astronomer Herschel came ont with the view that the Solar system was part of a much bigger star system, namely the Galaxy. This vision was again expanded in the 20th century by American astronomer Hubble, who contented, that the universe consisted of millions of galaxies.
According to modern astronomy the universe consists of everything that is in the cosmos and that can affect us by means of physical forces. This therefore excludes anything that is physically undetectable.
How did the universe begin?
There are many theories regarding the beginning of the universe. The pulsating theory says that the universe cyclically spreads and contracts, cach cycle taking billions of years. One of the most commonly accepted theories in modern times is the 'Big bang theory. According to this theory the universe began some 10-13 thousand million years ago with the explosion of an unimaginably dense ball of matter or primeval atom and has been expanding since then.
There is no satisfactory answer as to why the Big Bang occurred, but the theory is supported by the evidence that the universe is constantly expanding.
Will the Sun ever burn out?
The great fire of the Sun has burned non-stop for around 5000 million years and there is no apparent sign of it going out. We on Earth soak up only about one-hundred-millionth of the Sun's vast energy. The rest of its awesome output of heat and light vanishes beyond the planets and into space.
The Sun is composed of almost 75 percent hydrogen and 25 percent helium, plus much smaller amounts of oxygen, carbon, neon, nitrogen, magnesium, iron and silicon. It is known as a main sequence star, one that shines by burning hydrogen.
At the Sun's heart, the hydrogen was once compressed with such force that it started a nuclear reaction. In this giant furnace, the hydrogen is converted by nuclear fusion into another combustible gas, helium, in a reaction similar to that in an H- bomb. Thus, the Sun is both burning fuel and creating it. As the hydrogen store diminishes, its stock of helium grows. The light and heat now coming from the Sun were actually produced in its core many million of years ago.
The helium that the Sun produces is only about
92.3 percent of the hydrogen it burns. The other 7.7 percent is in several forms of energy, mainly heat, light and X-rays. This loss of hydrogen is slight when compared to the Sun's enormous bulk. Even though it is composed of light gas, the Sun weighs some 30000 times as much as the Earth. The Sun loses about 4 million tonnes of matter every second.
Scientists predict that the Sun has enough hydrogen to keep the fire going for another 5000 million years, about as long as it has already burned.
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