The Hubble Telescope has accustomed us to spectacular images of our Universe. Should we expect even more breathtaking images with his successor (and not his replacement), the James Webb?
the james webb telescope continues to progress through space to its final location. Since its take-off on December 25, 2021, the space observatory has deployed its main elements (heat shield, mirrors). There are still 5 months until the JWST is fully operational. It is only then that he will be able to begin to observe the Universe in the infrared.
The first images that will be immortalized by the James Webb are eagerly awaited. But what will they look like, exactly? Should we expect pictures even more striking than those obtained by the Hubble telescope ? Some astronomers are anxious not to let this idea spread too much, at the risk of creating disappointments.
« It’s time for us to start framing the audience’s expectations for what JWST footage will look like. They will be amazing and beautiful, but we will not get images with a higher spatial resolution than we get with Hubble », explained Astronomer Andras Gaspar of Steward Observatory, Arizona, on Twitter, Jan.9, 2022.
According to him, to present the James Webb as the successor to Hubble (this is however what made nasa, who prefers to talk about “Successor” rather than “replacement”) would even be a misnomer. It seemed more realistic to him to say that the JWST was the successor of Spitzer, who completed his mission in early 2020 and who observed in the infrared.
“Don’t expect to be blown away by all the pictures”
« In a way, [les images] are likely to be less visually impressive than some of the ones you’ve seen with Hubble », added Michael Merrifield, professor of astronomy at the University of Nottingham, also on Twitter. He adds that ” much of the beauty of Hubble’s images comes from the obscuring effects of the sooty ‘dust’ that permeates the space, giving them their dramatic ‘shadows’ and three-dimensional appearance, which will be somewhat lacking in the infrared, where dust is much more transparent ».
In summary, insists the scientist, “ don’t expect to be blown away by all the pictures – it’s the science that will be amazing “. We can better understand the difference thanks to the comparison next: the same star is seen here by Hubble on the left, and in a simulated view of what we will get with the James Webb on the right.
NASA gave another example of a structure, the Carina Nebula, observed by Hubble in the visible domain then in the infrared (Hubble can only go as far as the near infrared, while the JWST will see as far as the middle infrared, i.e. further into the past of the Universe).
Even if we cannot hope to discover absolutely spectacular views of the sky every day with the JWST, this does not mean that the observatory will not be able to impress us. For example, as Michael Merrifield points out, « some things like planetary systems that form around others stars emit a lot of light in the infrared, so the JWST should offer an unprecedented view of it ».