Expert explains how the James Webb Space Telescope has taken pictures of galaxies that shouldn't exist

Researchers have been attempting to understand the cosmic timeline for years, but there’s one piece of equipment that might be unravelling it all.

Stars, galaxies and everything in between have been capturing the interest of scientists for as long as we can remember, so it’s only natural that when a telescope shows contrasting data, things look a little muddled.

This is where Dr Katie Mack, a cosmologist, has decided to bring in her expertise to the table to share why this could be happening.

Lending her hand to BBC Science Focus, Mack explained that The James Webb Space Telescope, which has been sending back science data since 2022, provided data that stumped researchers.

She noted that it has been showing scientists images of galaxies that appear to have formed or matured a lot earlier than their models had predicted.

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But fret not, Mack explained that the telescope is not only looking at galaxies more than 13 billion years away from us, but it’s also providing pretty grainy pictures.

With the dating that the telescope has been giving cosmologists, it appears as though there hasn’t even been enough time since the Big Bang for these massive galaxies to have formed.

While many within the industry were worried that this discredits The Big Bang Theory, Dark Matter and much more, Mack suggests looking a little deeper at the data.

She explained that while the telescope gives amazing images of nearby nebulae, its images of the most distant galaxies are like ‘fuzzy little dots’.

This is due to the spectrum of the light, or how much light is arriving at different colours.

NASA

She said that there are two ways that the telescope can examine a source’s light.

It can either take a "spectrum by spreading out the light with a spectrograph (which works a bit like a prism) and examining the brightness at each colour, or it can use filters that block all but a select range of colours."

Then, by comparing this data to simulations of the spectrum expected for a galaxy with those same properties, they are able to determine the galaxy’s redshift.

This redshift is what tells us which moment in the universe’s history we’re looking at.

But based on model spectrum comparisons, a lot of the galaxies either have too many stars, or stars that are too old when they would have lived.

This could be due to a few different reasons.

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It’s possible that the photometric measurements were inaccurate due to telescope calibration issues.

Or it could be that they were only seeing very small patches of the sky or a clump of galaxies ‘not representative of the norm’.

It may also be due to the models of galaxy spectra being based on closer galaxies, which isn’t suitable for distant galaxies.

But if those galaxies really are super massive and previous measurements were wrong, cosmologists would have to ‘completely rethink cosmic evolution’ - which Mack finds to be an exciting prospect.

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