Cosmic Snapshots : A galaxy shot through by another. The Webb telescope peers through dust and gas to capture a stunning portrait.

Scientists last week published the latest images from NASA's James Webb Space Telescope. The newest release documents the Cartwheel galaxy, which is about 500 million light-years from our planet and is aptly named for its wheellike appearance, complete with a center hub, a tire and even wavy, fluorescent spokes.

The Webb also recorded two smaller companion galaxies alongside Cartwheel.

The new images come on the heels of NASA's July 12 unveiling of five initial scenes captured by the telescope.

Astronomers have been studying the Cartwheel galaxy for decades. Initially, it was inspected from two ground observatories in Australia. But it is best known through the Hubble Space Telescope, which produced images in the 1990s with more details of the galaxy's makeup.

Cartwheel's appearance comes from a collision of two galaxies hundreds of millions of years ago. 

''We guess that the Cartwheel probably started out looking something like the Milky Way, and then this other galaxy moved through,'' said Marcia Rieke, the research group leader for the near-infrared camera, or NIR-Cam, one of the Webb telescope's scientific instruments.

The smaller galaxy, though, rather than getting stuck in the large spiral it penetrated, continued on, moving away from the larger one. It is not visible in the image NASA published.

Galactic collision are not uncommon in deep space, though it is rare for them to result in such a perfect shape that inspires human curiosity.

Kirk Borne, who was the principal investigator for the Hubble observation of the Cartwheel but was not involved with the Webb, said that the galaxy's strange shape has motivated astronomers to study it.

Because a smaller galaxy crashed into a larger one - and straight through its middle - it was less disruptive to the shape of each galaxy.

''What changed the Cartwheel's shape was the influence of this galaxy's gravitational field that changed the orbit of the stars in the original Cartwheel galaxy,'' Dr. Rieke said.

Dr. Borne, who has studied other collisions of galaxies, described the smaller galaxy as a bullet that shot through the large one. After the observation of the cosmic object in the 1990s, the scientists noticed a trail of hydrogen gas left behind that was following the smaller galaxy, which Dr. Borne called the ''smoking gun'' indicating that it had kept moving after creating Cartwheel's new formation.

Already 1.5 times the size of the Milky Way, Cartwheel is still expanding, and new stars are being formed both inside and its outer ring and at its edge. However, there is no concrete answer as to how large Cartwheel will become, when it will stop growing or what shape it will take when it does.

The images of Cartwheel were already in hand on July 12, though they were not available to the public last week. To make them more visually clear, vivid, blue-hued young stars and redtoned molecules from older stars and space dust floating between the rings are highlighted.

While the images are colorful, Joseph DePasquale, a senior science visuals developer at the Space Telescope Science Institute, which manages the Webb and Hubble spacecraft, emphasized that the stars and dust are actually detected as infrared light, which is invisible to the human eye.

The new technology to detect that light in such detail is what distinguishes Webb's images. While Hubble had some capabilities to record light in the infrared spectrum, Webb's are more advanced.

The NIRCam for instance, which was built by about 25 people working with Dr.  Rieke over 11 years, distinguishes the stars' infrared hues from one another.

When Hubble captured Cartwheel in the 1990s, the galaxy's ''spokes'' were obscured by gas clouds that scattered light, making it hard to see the thousands of stars  forming within.

Now, because the Webb can study mid-infrared and near infrared- light wavelengths, it is able to filter past the space dust. That helps to confirm some of the theories of Cartwheels makeup and to uncover new information, such as the lack of star information in some areas between the spokes of the wheel.

''I think the combination of the two telescopes, far from making one of them obsolete, this is actually just boosting the benefits and power of Hubble because now we can do these comparisons,'' Dr. Borne said.

The World Students Society thanks author Anastasia Marks.


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