heic2607 — Photo Release

Hubble revisits Crab Nebula to track 25 years of expansion

23 March 2026

Nearly a millennium ago, astronomers witnessed a brilliant new star blazing in the sky — a supernova so bright it was visible in daylight for weeks. Today, its expanding remnant, the Crab Nebula, continues to evolve 6,500 light-years away. First linked to historical records by Edwin Hubble, the nebula has since been studied in exquisite detail by the NASA/ESA Hubble Space Telescope, which has now revisited this ancient explosion to trace its ongoing expansion and transformation.

A quarter-century after its first observations of the full Crab Nebula, the Hubble Space Telescope has taken a fresh look at the supernova remnant. The Crab Nebula is the aftermath of SN 1054, located 6,500 light-years from Earth in the constellation Taurus.

The result is an unparalleled, detailed look at the aftermath of a supernova and how it has evolved over Hubble’s long lifetime. A paper detailing the new Hubble observation is published in The Astrophysical Journal.

The supernova remnant was discovered in the mid-18th century, and in the 1950s Edwin Hubble was among several astronomers who noted the close correlation between Chinese astronomical records of a supernova and the position of the Crab Nebula. The discovery that the heart of the Crab contained a pulsar — a rapidly rotating neutron star — that was powering the nebula’s expansion finally aligned modern observations and ancient records.

In its new image of the nebula, Hubble has captured extraordinary details of its filamentary structure, as well as the considerable outward movement of those filaments over 25 years, at a pace of 5.5 million kilometres per hour. Hubble is the only telescope with the combination of longevity and resolution capable of capturing these detailed changes.

For better comparison with the new image, Hubble’s 1999 image of the Crab was re-processed. The variation of colors in both of the Hubble images shows a combination of changes in local temperature and density of the gas as well as its chemical composition.

The science team has noted that the filaments around the periphery of the nebula appear to have moved more compared to those in the centre and that rather than stretching out over time, they appear to have simply moved outward. This is due to the nature of the Crab as a pulsar wind nebula powered by synchrotron radiation, which is created by the interaction between the pulsar’s magnetic field and the nebula’s material. In other well-known supernova remnants, the expansion is instead driven by shockwaves from the initial explosion, eroding surrounding shells of gas that the dying star previously cast off.

The new, higher-resolution Hubble observations are also providing additional insights into the 3D structure of the Crab Nebula, which can be difficult to determine from a 2D image. Shadows of some of the filaments can be seen cast onto the haze of synchrotron radiation in the nebula’s interior. Counterintuitively, some of the brighter filaments in the latest Hubble images show no shadows, indicating they must be located on the far side of the nebula.

According to the science team, the real value of Hubble’s Crab Nebula observations is still to come. The Hubble data can be paired with recent data from other telescopes that are observing the Crab in different wavelengths of light. The NASA/ESA/CSA James Webb Space Telescope released its infrared-light observations of the Crab Nebula in 2024. Comparison of the Hubble image with other contemporary multiwavelength observations will help scientists put together a more complete picture of the supernova’s continuing aftermath, centuries after astronomers first wondered at a new little star twinkling in the sky.