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Credit & Copyright: Tommy Lease
(Denver Astronomical Society)
Explanation:
The interstellar cloud of dust and gas captured in this
sharp telescopic snapshot is seen to change its appearance
noticeably over periods as short as a few weeks.
Discovered over 200 years ago and cataloged as NGC 2261,
bright star R Monocerotis lies at the tip of the fan-shaped nebula.
About one light-year across and 2500 light-years away,
NGC 2261 was studied
early last century by astronomer Edwin Hubble and
the mysterious cosmic cloud is now more famous as
Hubble's Variable Nebula.
So what makes Hubble's nebula vary?
NGC 2261 is composed of a dusty
reflection nebula
fanning out from the star R
Monocerotis.
The leading
variability explanation
holds that dense knots of obscuring dust pass close to
R Mon
and cast
moving
shadows
across the dust clouds in the rest of
Hubble's
Variable Nebula.
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Based on Astronomy Picture
Of the Day
Publications with keywords: reflection nebula
Publications with words: reflection nebula
See also: