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We typically think of the Oort cloud as scattered ice balls floating far from the Sun, yet still tied to it gravitationally. Occasionally, some wayward gravitational perturbation will knock one of them a weird way and create a long-period comet, which might briefly delight us lowly humans by providing something interesting in the sky to look at. But what the Oort cloud actually looks like and how it is affected by forces greater than just our solar system has remained somewhat of a mystery. A new paper from researchers at the Southwest Research Institute and the American Museum of Natural History tries to shine a light on what this invisible part of the solar system looks like \u2013 at least the part that is only 1,000 to 10,000 times farther away from the Sun as Earth is.<\/p>\n
<\/p>\n That part called the \u201cinner\u201d Oort cloud is considered slightly more populated than the \u201couter\u201d Oort cloud, which ranges from 10,000 AU to 100,000 AU. Overall, potentially trillions of icy bodies are thought to be floating deep in space, though we only ever see the ones that show up in the inner solar system as long-period comets.\u00a0<\/p>\n Estimating the cloud\u2019s structure requires more than understanding the planet\u2019s gravitational forces. While they still have an impact, there is a larger player in the orbital mechanics of these icy rocks\u2014the galaxy itself.<\/p>\n There\u2019s a concept known as the \u201cGalactic tide\u201d. As our solar system moves through the galaxy, it is subjected to gravitational forces of other objects, like stars and black holes, that are closer or farther away from it. Like Earth\u2019s Moon forces the water on the surface towards it due to its gravity, the galactic center, where most of the galaxy\u2019s mass is, affects large objects in our solar system.<\/p>\n \n