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Owl Nebula

March 17, 2018

An owl stares at us from the Big Dipper — the death mask of a star. It consists of several concentric “bubbles” of gas blown into space by the dying star. It’s nice and round, and seen through a large telescope or in photographs, it has two dark patches that look like the eyes of an owl.

Astronomers have been keeping an eye on the Owl Nebula since it was discovered more than two centuries ago. Yet quite a bit about the nebula is still poorly understood. That includes its distance. Estimates published in the last decade and a half range from about a thousand light-years to about three thousand. Without knowing its distance, you can’t pin down its size, either. And without knowing its size, you can’t tell just when the nebula began to form.

One of the most extensive studies of the Owl says it began forming about 8,000 years ago as seen from Earth.

Because of changes in the nuclear reactions in the star’s core, it had puffed up to gigantic proportions. As those reactions began to shut down, gas at the surface flowed out into space, forming a faint “halo.” Later, much more gas flowed outward, forming the nebula’s outer shell. And later still, a faster wind began blowing, forming the inner shell. A cavity inside that shell contains less material, so it forms the eyes — the visage of a celestial owl.

And the Owl Nebula is near the top right corner of the Big Dipper’s bowl as darkness falls right now — the beautiful death mask of a star.

Script by Damond Benningfield

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