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 has 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 turning counterclockwise.

NGC 4622 is a rare example of a spiral galaxy with arms pointing in opposite directions. What caused this galaxy to behave differently from most galaxies? 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 core provides new evidence for a merger between NGC 4622 and a smaller galaxy. This information could be the key to understanding the unusual leading arms.

Galaxies, which consist of stars, gas, and dust, rotate very slowly. Our Sun, one of many stars in our Milky Way Galaxy, completes a circuit around the Milky Way every 250 million years.

NGC 4622 resides 111 million light-years away in the constellation Centaurus. The pictures were taken in May 2001 with Hubble's Wide Field Planetary Camera 2.

The science team, consisting of Ron Buta and Gene Byrd from the University of Alabama, Tuscaloosa, and Tarsh Freeman of Bevill State Community College in Alabama, observed NGC 4622 in ultraviolet, infrared, and blue and green filters. Their composite image and science findings were presented at the meeting of the American Astronomical Society in January of 2002.

Image Credit: NASA and the Hubble Heritage Team (STScI/AURA) Acknowledgment: Dr. Ron Buta (U. Alabama), Dr. Gene Byrd (U. Alabama) and Tarsh Freeman (Bevill State Community College)

EDITOR'S NOTE #1: For additional information, please contact Dr. Ron Buta, University of Alabama, Dept. of Physics and Astronomy, Box 870324, Tuscaloosa, AL 35487-0324, (phone) 205/348-3792, (e-mail) buta@sarah.astr.ua.edu or

Dr. Gene Byrd, University of Alabama, Dept. of Physics and Astronomy, Box 870324, Tuscaloosa, AL 35487-0324, (phone) 205/348-3793, (e-mail) byrd@possum.astr.ua.edu or

Dr. Keith Noll, Hubble Heritage Team, Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, (phone) 410-338-1828, (fax) 410-338-4579, (e-mail) noll@stsci.edu.

Electronic images and additional information are available at: http://heritage.stsci.edu and http://oposite.stsci.edu/pubinfo/pr/2002/03 and via links in

http://oposite.stsci.edu/pubinfo/latest.html
http://oposite.stsci.edu/pubinfo/pictures.html
http://hubble.stsci.edu/go/news

EDITOR'S NOTE #2: "Picture-Perfect" Web Site Sheds Light on Hubble's Colorful Snapshots

Hubble Space Telescope's beautiful and vividly colorful pictures of galaxies, planets, and nebulae frequently invite the question "are those colors real?" That question can now be answered by taking a look at the making of Hubble images when visiting a new web offering from the Space Telescope Science Institute's popular "HubbleSite," called "Behind The Pictures." The new site offers a tour of Hubble's image factory - an in-depth look at how the color pictures are actually constructed from separate black and white photos. "Behind the Pictures" explains how astronomers use color to enhance the scientific value of Hubble images to more easily visualize celestial objects that ordinarily would be invisible to the human eye.

For the full story, visit "Behind the Pictures" at http://www.hubblesite.org/sci.d.tech/behind_the_pictures.