Why Lenses Happen
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Astro-Dragon asked 'what causes gravitational #lensing?' and here is the responce:
Gravitational lensing is an uncommon/rare phenomenon caused by the light of a background, often blue galaxy being apparently 'bent' or lensed by a closer, very massive galaxy. This happens according to the law that with enough gravity, you can bend light. Imagine space as a sort of stretchy fabric. You place an object on it, and it bends down. When you roll a marble on it, the marble will change its course to fit the bend created by the object. When this happens, you will also see the light being moved around it, because if you roll the marble slowly enough at the side, you will see the marble change its course with the shape of the curve, and sometimes even fall into it. This happens with galaxies, with the light(marble) being bent around the galaxy's gravity. However, galaxies alone are not often enough to cause strong lensing. A type of matter discovered recently, called Dark Matter, seems to make up a large portion of the universe. We can not see it, hear it, feel it, or even detect it at all. We only know it's there because the attraction of matter alone is not enough to explain many phenomena in this universe, including lenses. Dark Matter is often very common in areas with strong gravitational lensing. The dark matter adds on that extra amount of gravity needed to make the light bend around it. Despite knowing this much, I don't know why some other things about lensing happen, such as why the lens appears as a curve around the galaxy, instead of a cone facing into the center, and why the lens here is so red- but above you, you have a basic definition of why it happens.
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Astro-Dragon
Thanks 😄 i understand now 😃
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