The Hubble Space Telescope has revisited one of the most famous objects in the sky: the remnants of an exploded star first observed by Chinese astronomers in the 11th century.
Known as the Crab Nebula, this expanding remnant of a stellar explosion is evolving still today, 6,500 lightyears from Earth.
Astronomers say Hubble's multiple observations of the Crab Nebula are giving them a detailed look at the supernova remnant and how it has evolved over decades.
An ancient stellar explosion
About 1,000 years ago, astronomers looked up at the night sky and saw a 'new star' where there hadn't been one previously.
This new star was in fact a stellar explosion known as a supernova, which was so bright it was even visible during the day, and for several weeks.
The supernova remnant that formed in the aftermath is known as the Crab Nebula, because early observers who discovered it through their telescopes felt it resembled a crab.
In the 1950s, astronomers noted the correlation between ancient Chinese astronomical records of the supernova – known as SN 1054 – and the location of the Crab Nebula.
The discovery of a pulsar – a spinning neutron star – at the heart of the Crab Nebula, powering the nebula's expansion, proved the link between the ancient and modern observations.
Hubble's new view of the Crab
This image of the Crab Nebula by the Hubble Space Telescope, captured in 2024, provides a new view of its intricate structure.
This is not the first time Hubble has looked at the Crab Nebula, and the space telescope's longevity means it's given astronomers the chance to track changes in the nebula over 25 years.
Astronomers have re-processed the Hubble Space Telescope's 1999 image of the Crab Nebula and presented it alongside the 2024 image.
They say the variation of colour in both the Hubble images shows a combination of changes in temperature and density of the gas, as well as its chemical composition.
The filaments around the edge of the Crab Nebula seem to have moved more compared to those in the centre.
Astronomers say that, rather than stretching out over time, the filaments seem to have simply moved outward.
This, they say, is because the Crab is powered by the interaction between the pulsar’s magnetic field and the nebula’s material.
In other supernova remnants, expansion is driven by shockwaves from the explosion.
And astronomers say the new Hubble observations are giving them insights into the 3D structure of the Crab.
What's more, the James Webb Space Telescope's view of the Crab Nebula reveals how it looks in infrared light, giving astronomers yet another perspective of this fascinating supernova remnant.
