Introduction
The universe is everything anything that exists. It came into life 13 billion years ago with an explosion so powerful that its effects can still be felt today. The universe is still a mystery to scientists. Nobody knows exactly how big it is or what shape it takes, where it comes from or what it is expanding into.
What shape?
Scientists now know that the universe is expanding, but what is it expanding into? Scientists claim that it is not expanding into anything because nothing exists outside the universe. Instead, the universe has no outside edge, and space itself is stretching to accommodate the expanding matter in the universe. The universe is not hollow sphere with a centre and an edge, as people used to think. The force of gravity shapes and distorts the universe so that it has no centre or outside edge. Gravity may even force space to curve. If the universe curves enough, it could close back in on itself. This means that if you travelled in a straight line long enough, you would end back where you started!
Expansion
In 1929, an astronomer named Edwin Hubble realized that the universe was expanding and suggested that it must have been much smaller in the past. He believed that it began with an immense explosion called the Big Bang. The force of the Big Bang can still be felt billions of years later. The universe is expanding continuously, entire clusters of galaxies moving away from each other at phenomenal speeds. Not everything in the universe is expanding, however. Our solar system and even our galaxy stay the same size because they are held together by gravity. Only enormous clusters of galaxies billions of light years wide drift away from each other because the distances between them are too great for gravity to have any effect.
A gallery of galaxies
In 1995, the hubble space telescope took a 240 hour exposure of a speck of sky no bigger than a grain of sand that lay above the handle of the Big Dipper Constellation. The picture revealed a univers teeming with thousands upon thousands of galaxies. If the entire sky is as densely populated as this, then the universe could contain over 50 billion galaxies! Pictures of hubble shows clusters of stars from throughout history of the universe. Some are estimated to be over 13 billion light years away, which means that in effect we are staring back in time to the origins of the universe itself.
Some important facts
1) Only by looking at things in scale we can get an idea of how enormous the universe is. Our solar system stretches to 1.6 light years.
2) Stars often group together in clusters. These collections can contain hundreds of stars and can stretch for thousands of light years.
3) When we zoom out even further, we can begin to understand how big the universe really is.
4) The milky way galaxy, is thousands of times larger than the solar system, stretching over 100,000 light years in diameter.
5) We know that galaxies are moving away from us because of the colour of their light. We see different colours depending upon the wavelength of light. If a star is moving away from Earth, the wavelengths of its light are stretched making them appear red. This is called a star's red shift.
The universe is everything anything that exists. It came into life 13 billion years ago with an explosion so powerful that its effects can still be felt today. The universe is still a mystery to scientists. Nobody knows exactly how big it is or what shape it takes, where it comes from or what it is expanding into.
What shape?
Scientists now know that the universe is expanding, but what is it expanding into? Scientists claim that it is not expanding into anything because nothing exists outside the universe. Instead, the universe has no outside edge, and space itself is stretching to accommodate the expanding matter in the universe. The universe is not hollow sphere with a centre and an edge, as people used to think. The force of gravity shapes and distorts the universe so that it has no centre or outside edge. Gravity may even force space to curve. If the universe curves enough, it could close back in on itself. This means that if you travelled in a straight line long enough, you would end back where you started!
Expansion
In 1929, an astronomer named Edwin Hubble realized that the universe was expanding and suggested that it must have been much smaller in the past. He believed that it began with an immense explosion called the Big Bang. The force of the Big Bang can still be felt billions of years later. The universe is expanding continuously, entire clusters of galaxies moving away from each other at phenomenal speeds. Not everything in the universe is expanding, however. Our solar system and even our galaxy stay the same size because they are held together by gravity. Only enormous clusters of galaxies billions of light years wide drift away from each other because the distances between them are too great for gravity to have any effect.
A gallery of galaxies
In 1995, the hubble space telescope took a 240 hour exposure of a speck of sky no bigger than a grain of sand that lay above the handle of the Big Dipper Constellation. The picture revealed a univers teeming with thousands upon thousands of galaxies. If the entire sky is as densely populated as this, then the universe could contain over 50 billion galaxies! Pictures of hubble shows clusters of stars from throughout history of the universe. Some are estimated to be over 13 billion light years away, which means that in effect we are staring back in time to the origins of the universe itself.
Some important facts
1) Only by looking at things in scale we can get an idea of how enormous the universe is. Our solar system stretches to 1.6 light years.
2) Stars often group together in clusters. These collections can contain hundreds of stars and can stretch for thousands of light years.
3) When we zoom out even further, we can begin to understand how big the universe really is.
4) The milky way galaxy, is thousands of times larger than the solar system, stretching over 100,000 light years in diameter.
5) We know that galaxies are moving away from us because of the colour of their light. We see different colours depending upon the wavelength of light. If a star is moving away from Earth, the wavelengths of its light are stretched making them appear red. This is called a star's red shift.
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