Nasa releases stunning Webb images of a galactic merger — At left is NGC 2937, an elliptical galaxy that looks like a tiny teal oval and is nicknamed the Egg. At right is NGC 2936, a distorted spiral galaxy nicknamed the Penguin, which is significantly larger. Nasa, ESA, CSA, STScI

Nasa on Friday released a pair of images taken by the James Webb Space Telescope showing two galaxies, one nicknamed the Penguin and the other the Egg, in the process of merging in sort of a cosmic ballet as the US space agency marked two years since it unveiled the orbiting observatory’s first scientific results.

Webb, which was launched in 2021 and began collecting data the following year, has reshaped the understanding of the early universe while taking stunning pictures of the cosmos. The two galaxies in the images are situated 326 million light years from Earth in the constellation Hydra. A light year is the distance light travels in a year, 9.5 trillion kilometres).

“We see two galaxies, each a collection of billions of stars. The galaxies are in the process of merging. That’s a common way that galaxies like our own build up over time, to grow from small galaxies — like those that Webb has found shortly after the Big Bang – into mature galaxies like our own Milky Way,” said Jane Rigby, Nasa Webb senior project scientist.

Since becoming operational, Webb has observed galaxies teeming with stars that formed within a few hundred million years of the Big Bang event that marked the beginning of the universe about 13.8 billion years ago.

The mingling Penguin and Egg galaxies are collectively known as Arp 142. They are shown in the imagery joined by a haze that is a mix of stars and gas amid their slow-motion merger.

The Penguin galaxy, so dubbed because its shape from the perspective of the telescope resembles that flightless bird, including a beak-like region, is formally called NGC 2936. It is a spiral-shaped galaxy, now a bit distorted. The Egg galaxy, also named for its shape, is formally called NGC 2937. It is a compact elliptical-shaped galaxy. Together their appearance is suggestive of a penguin guarding its egg.

Their interaction, according to Nasa, was set in motion between 25 and 75 million years ago, and they are expected to become a single galaxy hundreds of millions of years from now.

Infrared

Webb has detected the earliest-known galaxies and has provided insight into areas such as the composition of planets beyond our solar system, known as exoplanets, and the nature of star-forming regions in the cosmos.

“This mission has allowed us to look back to the most distant galaxies ever observed and understand the very early universe in a new way,” said Mark Clampin, astrophysics division director at Nasa headquarters. “For example, with Webb, we’ve found that these very early galaxies are more massive and brighter than we expected, posing the question: how did they get so big so quickly?”

Webb was designed to be more sensitive than its Hubble Space Telescope predecessor, which also is continuing its work. Webb looks at the universe mainly in the infrared, while Hubble has examined it primarily at optical and ultraviolet wavelengths.

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The Penguin and the Egg. Nasa, ESA, CSA, STScI

The Rho Ophiuchi cloud complex, the closest star-forming region to Earth, is seen in a composite of separate exposures acquired by the James Webb Space Telescope using the NIRCam instrument. Nasa, ESA, CSA, STScI, Klaus Pontoppidan and Alyssa Pagan

“Webb is the largest, most powerful telescope ever put in space. It specialises in capturing infrared light — wavelengths of light longer than our eyes can see. With its incredible sensitivity to those wavelengths, we’ve been able to look back into the early universe in a way previous missions couldn’t, see through dust and gas into the heart of star formation, and examine the composition of exoplanet atmospheres like never before,” Clampin said.