Einstein's Cross facts for kids
Einstein's Cross is a special sight in space. It shows four images of the same very distant object called a quasar. A quasar is like a super bright, active center of a galaxy.
This amazing view happens because of something called gravitational lensing. Imagine a giant magnifying glass in space! A huge galaxy, named ZW 2237+030 (also called Huchra's lens), sits between us and the quasar. Its massive gravity bends the light from the quasar, making it look like there are four separate images of it.
The quasar itself is incredibly far away, about 8 billion light years from Earth. A light-year is the distance light travels in one year. The galaxy that acts as the lens is much closer, only about 400 million light years away.
Some people who love looking at the stars, called amateur astronomers, can see parts of Einstein's Cross. But they need very dark skies and large telescopes to spot it.
Contents
What is a Quasar?
A quasar is one of the brightest objects in the universe. It's the extremely active center of a young galaxy. Quasars get their energy from a supermassive black hole that pulls in gas and dust around it. This process releases huge amounts of light and other energy.
How Does Gravitational Lensing Work?
Bending Light with Gravity
Gravitational lensing is a cool effect predicted by Albert Einstein's theory of relativity. It says that very heavy objects, like galaxies or clusters of galaxies, can bend light. This is similar to how a glass lens bends light to focus it.
Creating Multiple Images
When a massive object (the "lens") is directly between us and a distant light source (like a quasar), its gravity can bend the light in several ways. This can make the distant object appear as multiple images, a ring, or an arc. Einstein's Cross is a perfect example of multiple images.
Measuring Distances in Space
Light Years and Redshift
Scientists use different ways to measure how far away things are in space. One way is using light years, which is how far light travels in a year. Another important tool is called redshift.
Understanding Redshift
Redshift happens when light from a distant object stretches out as it travels through the expanding universe. This stretching makes the light look redder. The more redshift an object has, the faster it's moving away from us, and the farther away it generally is. This helps astronomers figure out the quasar's incredible distance.
Images for kids
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Diagram of an Einstein cross formed by gravitational lensing
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Another lensed quasar, HE0435-1223 in Eridanus, and its surroundings.
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Hubble Space Telescope captures Einstein Cross.
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12 Einstein crosses discovered by Gaia in 2021
See also
In Spanish: Cruz de Einstein para niños
