Astronomers have found a spiral
galaxy that may be spinning to the beat of a different
cosmic drummer. To the surprise of astronomers,
the galaxy, called NGC 4622, appears to be rotating
in the opposite direction to what they expected.
Pictures from NASA's Hubble Space Telescope helped
astronomers determine that the galaxy may be spinning
clockwise by showing which side of the galaxy is
closer to Earth. This Hubble telescope photo of
the oddball galaxy is presented by the Hubble Heritage
team. The image shows NGC 4622 and its outer pair
of winding arms full of new stars.
Click on image for larger version.
1. Why are astronomers surprised
about the galaxy's clockwise rotation?
Astronomers are puzzled by the clockwise rotation
because of the direction the outer spiral arms are
pointing. Most spiral galaxies have arms of gas
and stars that trail behind as they turn. But this
galaxy appears to have two "leading" outer
arms that point toward the direction of the galaxy's
clockwise rotation. To add to the conundrum, NGC
4622 also has a "trailing" inner arm that
is wrapped around the galaxy in the opposite direction
it is rotating. Based on galaxy simulations, a team
of astronomers had expected that the galaxy was
2. What may have caused the clockwise rotation and
"leading" outer arms?
Astronomers suspect that NGC 4622 interacted with
another galaxy. Its two outer arms are lopsided,
meaning that something disturbed it. The new Hubble
image suggests that NGC 4622 consumed a small companion
galaxy. The galaxy's two leading outer arms provide
new evidence for a merger between NGC 4622 and a
Possible Supernova found in the
HST data for NGC 4622: learn