Just over a week after NASA dazzled the world with the first clutch of images from the James Webb Space Telescope, astronomers working with one of the pictures believe they have found the oldest galaxy ever imaged—one dating back 13.5 billion years, or just 300 million years after the Big Bang.
The age of a galaxy is measured by what is known as its red shift: as the universe expands, the wavelength of light is stretched into the red spectrum.
The redder the image, the greater the stretching and the farther—and older—the object in the image is. Analyzing the deep-field image the Webb telescope returned, a team led by astronomer Rohan Naidu of the Harvard Center for Astrophysics detected a galaxy with a shift that fixes it at the 13.5 billion year point.
“We’re potentially looking at the most distant starlight ever seen,” Naidu told France 24. The next step is to submit their findings for peer review that should hopefully validate their discovery.
The galaxy is not much as these things go. It measures 3,000 to 4,500 light years across and contains about a billion stars. In comparison, our Milky Way measures about 100,000 light years and contains an estimated 200 billion stars. But seeing something 13.5 billion light years away means we’re seeing it as it looked 13.5 billion years ago. Over time, the small, old galaxy would have merged with others nearby, forming a single, giant galactic mass.
