CfA2 Great Wall facts for kids
The Great Wall is one of the largest known structures in the Universe. Imagine a giant cosmic filament, like a long, thin thread made of galaxies! It's a huge group of galaxies that stretches across space.
This amazing structure is about 200 million light-years away from us. A light-year is the distance light travels in one year, so 200 million light-years is an incredibly vast distance!
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What is the Great Wall?
The Great Wall is not a solid wall like you might imagine. Instead, it is a very long, thin line of many galaxy clusters. These clusters are groups of hundreds or even thousands of galaxies.
How Big is the Great Wall?
This cosmic structure is truly enormous. It is over 500 million light-years long. That's like traveling across the entire Milky Way galaxy thousands of times! It is also 300 million light-years wide. But it is quite thin, only about 15 million light-years thick.
How Was it Discovered?
Scientists first found the Great Wall in 1989. They used special data from a "redshift survey." This survey helps astronomers measure how far away galaxies are and how fast they are moving. By mapping many galaxies, they saw this huge, wall-like pattern appear.
Why Can't We See All of It?
Astronomers don't know exactly how much farther the Great Wall extends. Our view of the universe is partly blocked by our own Milky Way galaxy. The Milky Way has a lot of gas and dust in its middle, called the Zone of Avoidance. This dust makes it hard to see distant objects clearly. Because of this, scientists can't tell if the Great Wall ends or if it continues on even further.
How Did the Great Wall Form?
Scientists believe that structures like the Great Wall form because of something called dark matter. Dark matter is a mysterious substance that we can't see directly. However, it has gravity, which pulls things together.
It's thought that dark matter creates a kind of invisible web throughout the universe. Normal matter, like the gas and dust that form stars and galaxies, gets pulled towards these dark matter "strings." Over billions of years, this normal matter gathers and forms the long, thin walls of super-galactic clusters that we see today, like the Great Wall. Dark matter helps shape the universe on the very largest scales.
Images for kids
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An axonometric representation of the CfA2 Great Wall. This shows its shape in three dimensions.
See also
In Spanish: Gran Muralla (astronomía) para niños
