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In the night sky: Orion
In the night sky: Orion

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Orion Glossary

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Oort cloud

A spherical cloud of icy bodies surrounding the Solar System and extending up to one-third of the way to the nearest star. It is sometimes called the Öpik-Oort cloud.

oxygen burning

The process by which, towards the end of their lives, massive stars fuse oxygen nuclei together to form silicon.