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Credit & Copyright: G. Byrd, R. Buta,
(Univ.Alabama, Tuscaloosa),
T. Freeman (Bevill State College),
NASA
Explanation:
While stirring a morning cup of coffee and thinking
cosmic thoughts many
astronomers
would glance at this Hubble Space
Telescope image of spiral galaxy NGC 4622 and assume that
the galaxy was
rotating
counterclockwise in the picture.
One hundred million light-years away in the
constellation
Centaurus, NGC 4622's gorgeous outer
spiral
arms, traced by bright bluish star clusters and dark dust lanes,
should be winding up like ... well, like
swirls in a cup of coffee.
But a
closer look at this galaxy reveals that a pronounced inner
spiral arm winds in the opposite direction.
So which way is this galaxy rotating?
Evidence
combining ground-based spectroscopy and the
sharp Hubble image data surprisingly indicates that the
galaxy is likely rotating
clockwise
in the picture, its outer spiral arms opening outward in the
direction of rotation.
There are further indications that a past collision
with a smaller companion galaxy has contributed to
NGC 4622's bizarre
rotational arrangement of spiral arms,
essentially unique among known large
spiral galaxies.
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NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: spiral arms - spiral galaxy - NGC 4622 - rotation
Publications with words: spiral arms - spiral galaxy - NGC 4622 - rotation
See also: