A massive galaxy cluster called MACS-J0417.5-1154. Image: NASA/ESA/CSA/STScI/Dr V Estrada-Carpenter (St Mary's University)
The questionable shape is actually the result of ‘gravitational lensing’ and the observations can help researchers learn about how the Milky Way looked in its teenage years.
The powerful James Webb Space Telescope has spotted a unique sight in the cosmos, which could help us understand how galaxies evolved over time.
The space observatory turned its instruments to a massive galaxy cluster called MACS-J0417.5-1154. This cluster is so large that it warps the fabric of space-time, distorting the appearance of galaxies behind it.
This effect is called gravitational lensing and is a benefit for astronomers, as it allows them to see details of distant galaxies in better detail – one of the first images from Webb benefitted from this effect.
But this gravitational lensing can also cause optical illusions, making galaxies seem smeared across the sky or appear multiple times. This illusion is what causes the unique question mark in the latest James Webb image.
In this image from Webb, two galaxies – a face-on spiral and a dusty red galaxy seen from the side – appear multiple times and trace the question mark shape across the sky. This galaxy cluster has been previously observed by the Hubble Space Telescope, but the dusty red galaxy that forms the question mark only comes into view with Webb’s instruments.
NASA said this is because the light gets trapped in cosmic dust, making the red galaxy invisible to Hubble, while Webb is able to spot this light through its infrared instruments. The observation has been well received by members of the team observing the cluster.
“This is just cool looking,” said Dr Marcin Sawicki. “Amazing images like this are why I got into astronomy when I was young.”
But there is more to these observations than the impressive scenery, as they also offer researchers a glimpse of what galaxies looked like billions of years ago.
“These galaxies, seen billions of years ago when star formation was at its peak, are similar to the mass that the Milky Way galaxy would have been at that time,” said Sawicki. “Webb is allowing us to study what the teenage years of our own galaxy would have been like.”
Last month, Webb uncovered mysteries within the Perseus Nebula, which will help scientists learn more about how stars are born.
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