JADES focused JWST on the same patch of sky as Hubble’s Ultra Deep Field, located in the Fornax Cluster.

While Hubble found an impressive 10,000 galaxies in the region, JWST’s image is 15 times larger, and contains a staggering 100,000 galaxies.

Astronomers are still sifting through this deluge, looking for the most distant galaxies among them.

One ‘easy’ way to pick out distant candidates is to use the fact that hydrogen gas absorbs almost all light at wavelengths shorter than 91nm, called the Lyman limit.

Since galaxies are filled with hydrogen, this creates a sharp ‘step’ in their ultraviolet and X-ray emissions.

However, as light travels through space it is stretched (or redshifted) due to the expansion of the Universe.

The longer it travels, the more it stretches, until this step in emissions moves into the visible range.

Astronomers can use the position of this ‘Lyman break’, to work out how far away a galaxy is.

For 28 hours over three days, JWST collected the faintest infrared spectra ever taken from 250 candidate galaxies, revealing the precise position of the Lyman break in each galaxy.

This confirmed that four of the galaxies had a redshift above 10, setting new distance records, including two with redshifts of 13.

JADES will now study Hubble’s Deep Field, a small region in Ursa Major, before returning to the Ultra Deep Field, so we can expect many more ‘most distant galaxies’ to be confirmed in the future.

The evolution of galaxies

The early Universe was a far busier place than it is today.

Ten billion years ago, the rate at which stars burst into life and galaxies crashed together was 10 times higher.

JWST aims to investigate the driving force behind this activity – as well as its sharp decline – by tracking galaxies over time to see how they have evolved.

JWST is able to study areas previously hidden from view and begin to reveal how the formation of stars – some of the smallest objects in the Universe, cosmologically speaking – can influence the structure and evolution of some galaxies, some of the largest objects in the Universe.

The Physics at High Angular resolution in Nearby Galaxies Survey (PHANGS) represents the largest survey of nearby galaxies in JWST’s first year of science.

Its international team of 100 researchers are investigating 19 diverse spiral galaxies and have already made observations of five of their targets, including the spiral galaxy, NGC 1433.

NGC 1433 lies 46 million lightyears from Earth in the Southern Hemisphere constellation of Horologium.

The galaxy has a tight, bright core that features a unique double ring of tightly wrapped spiral arms, wound into an oval structure along its central bar.

JWST’s sensitivity to infrared has revealed a network of cavities and huge bubbles of gas lining the galaxy’s spiral arms, which had previously been hidden by clouds of dust in the galaxy.

The cavities are formed by young stars interacting with the gas surrounding them, and so will help give key insights into how star formation shapes growing galaxies.

PHANGS will continue to survey galaxies with JWST, and combine these observations with data previously taken by other telescopes to conduct a complete census of star formation in nearby galaxies, beyond the Local Group, to reveal how star formation gave rise to, or impeded, the formation of the next generation of stars at earlier stages in the Universe’s evolution.

Stars blowing bubbles

Stars begin their lives in dense clouds of obscuring dust and gas, but JWST’s high-resolution infrared capabilities are able to pierce through this and reveal stars growing in their cosmic nurseries.

One of the first images released by JWST back in July 2022 was of NGC 3372, a young star-forming region 7,600 lightyears away, in the northwest corner of the Carina Nebula, NGC 3372.

JWST’s infrared instruments revealed the edge of a gigantic gaseous cavity – a huge bubble created by the intense radiation and stellar winds from nearby massive, hot, young stars, dubbed the Cosmic Cliffs.

As the ionised rim of the bubble pushes into the gas and dust of the nebula, the change in pressure can cause either a boom or bust – material either collapses to form new stars or erodes away, preventing star formation.

Dense clouds form more massive stars, which in turn drives the gas into voids and denser regions where lower-mass stars form.

As the growing stars pull material in, high-velocity jets of gas and dust stream from the stars’ poles.

These jets only appear briefly, during periods of active accretion, but astronomers have still managed to find 24 such flows.

Instead of a steady stream, these flows are chains of dense, fast-moving clumps, indicating that accretion occurs in a series of short, powerful bursts.

Monitoring these outflows allows astronomers to estimate how fast they move, how much mass they carry and their effect on growing stars and planets.

The chemical profiles of exoplanets

We now know of thousands of planets beyond our Solar System, but while we may know the size, mass and orbit of these worlds, understanding of the atmospheres above them has proved elusive.

Whether a ‘hot Jupiter’ or a small, rocky planet, knowing what is above the world gives key insights into their composition, formation and evolution.

However, JWST’s sensitive instruments can distinguish a far wider range of atmospheric molecules than ever before.

In August 2022, JWST achieved a hat-trick of firsts when it made its first science observation of an exoplanet, where it also obtained the first detailed exoplanet spectrum in near-infrared and the first indisputable evidence for carbon dioxide in an exoplanet’s atmosphere.

The exoplanet in question was WASP-39b, a hot gas giant 700 lightyears away, discovered in 2011.

It is roughly the same mass as Saturn, but with a diameter 1.3 times greater than Jupiter.

It orbits its parent star eight times closer than Mercury orbits the Sun, giving it a surface temperature of 900˚ Celsius.