The outer solar system has always been a mystery.  It is full of icy objects and comets.  The Oort Cloud is a region far beyond Pluto.  It is filled with icy relics from the solar system's formation.  Comets can hurtle toward Earth from the cloud, but scientists have never glimpsed its true shape.

A planetarium show in New York was preparing "Encounters in the Milky Way. "  This show was a deep dive into our home galaxy.  It was shaped by the movements of stars and other celestial objects.  They were fine-tuning a scene featuring what's known as the Oort Cloud.

One evening while watching the Oort Cloud scene, scientists noticed something strange.  "Why is there a spiral there? "  asked the museum's Jackie Faherty.  The inner section of the Oort Cloud, made of billions of comets, resembled a bar with two waving arms.  This was similar to the shape of our Milky Way galaxy.

Scientists had long thought the Oort Cloud was shaped like a sphere or flattened shell.  This shape was warped by the push and pull of other planets and the Milky Way itself.  The planetarium show hinted that a more complex shape could lie inside.  The museum contacted the researcher who provided the Oort Cloud data for the show.  He was also surprised to see the spiral.

The researcher was David Nesvorny.  He works with the Southwest Research Institute.  "It's kind of a freak accident that it actually happened, " said Nesvorny.  Realizing they'd stumbled on something new, the researchers published their findings in the Astrophysical Journal.  The spiral is "a striking shift in our understanding of the outer solar system, " said planetary scientist Andre Izidoro.  He works with Rice University and was not involved with the study.

The planetarium show opens to the public.  The show is called "Encounters in the Milky Way. "  You just never know what you're going to find.  This is especially true when exploring the outer solar system.

The Hidden Spiral: A Surprising Discovery in the Outer Solar System

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