James Webb vs Hubble, the differences between their images of space

Images credit: NASA

The James Webb Space Telescope has finally unleashed its full potential and has pointed its main mirror at five different targets secretly decided by NASA. However, if he was not surprised by the revealed panoramas, perhaps it is because he had seen them before, the eyes of the Hubble Space Telescope had already rested on them years ago. But a comparison between the before and after images will make us understand that the power of the James Webb is actually a milestone that is marking a new dawn in the age of astronomy and deep space exploration science.

What did the James Webb Telescope photograph?
On July 12, 2022, the day finally arrived when the first images taken by the James Webb Space Telescope (JWST) were revealed. From the beginning, the researchers in charge of the JWST chose to aim at five specific objectives:

A deep field image centered on a massive galaxy cluster
The WASP-96-b star system
The Southern Ring Nebula
The Stephan Quintet showing five closely spaced galaxies
The ‘cosmic cliffs’ of the Carina Nebula
But all these objectives had already been captured by the Hubble Space Telescope and although there is an atmosphere of nostalgia, the truth is that the observer who for more than three decades gave us the best views of the Universe, is now being surpassed by the James Webb. That is what science is all about, always progressing with an eye towards new discoveries that help us understand the reality we inhabit and with JWST a new era has just begun.

gravitational lensing
The first image revealed was the deep-field photograph centered on a massive galaxy cluster. In it you can see thousands of galaxies in the deep Universe very close to the cluster of galaxies SMACS 0723. Hubble had already given us an image similar to this one, however, the differences between the two are abysmal.

In the first image taken by Hubble you can see a composition in 7 filters that cover both optical and near-infrared wavelengths and that was taken in a total of 3.4 hours. In contrast, the James Webb had a total observation time of 12.5 hours and collected data with its near and mid-infrared devices. The main difference between the two photographs lies in the sharpness of the galaxies, which previously appeared as spots, can now be seen with their well-defined shapes: spiral, elliptical or ringed galaxies.

WASP-96-b star system
The system has as its host star a G-class star very similar to our Sun in mass, radius and temperature. Around it orbits the exoplanet WASP-96-b, which is a gas giant similar to Jupiter, although with half its mass, however, it has a quality that has made it special for astronomers: it is practically free of clouds.

The proximity to its star means that its atmosphere has an average temperature of just over 1000ºC and as it is a gas giant, it is expected to be rich in cloud formations like Jupiter itself, but it is not. Although the exoplanet WASP-96-b had already been observed before, the composition of its atmosphere had never been seen, until now that James Webb has revealed that there is a lot of water there!

South Ring Nebula
Nebulae are indicators of a dying star, when a star similar to the Sun dies, it does so in a peculiar and very striking way. First gently letting go of its outermost layers with which a gas-rich preplanetary nebula is generated. The core of the star then collapses to a size no larger than our planet, yet contains a full solar mass within it. This contraction generates that the stellar remnant, now converted into a white dwarf, heats up to such a degree that it ionizes and expels the material already present on the outskirts. The result is the beautiful nebulae that we have seen before thanks to Hubble.

The image above shows us the Southern Ring Nebula taken by Hubble, compared to the images below which are the most recent James Webb images. The difference is very clear, while in the first one only one star is observed in the center of the nebula, one of the JWST shots reveals that it is actually a binary system, it also shows us a remote spiral galaxy hidden in the left side. And not only that, one can almost swear that the filaments of dust and gas are palpable thanks to the razor sharpness.

The Stephen Quintet
This is the first compact group of galaxies discovered 150 years ago which is surprising since it is 290 million light years away. Within it there are two galaxies in the process of merging that are surrounded by two other galaxies that also gravitationally interact with each other. However, what appears to be a quintet from the terrestrial view, is actually something else; one of the galaxies is 40 million light-years away from its companions.

The colliding galaxies while merging are expelling gas favoring the formation of new stars and also generate the great current of material that can be observed in a wide variety of wavelengths thanks to the devices of the telescopes. Compare for yourself the Hubble result above and the new James Webb image below.