Crab Nebula

At a glance

Key points

A pulsar at its heart powers the glowing cloud.

• First nebula tied to a recorded supernova
• Powered by a pulsar spinning 30× a second
• Filaments expand at 5.5 million km/h

A pulsar wind nebula

The pulsar's wind of particles and magnetic field lights the inner nebula with blue-white synchrotron glow; Webb traced wisps following the field. Outer filaments glow in the colours of hydrogen, oxygen and sulfur.

From guest star to catalogue entry

In 1054 Chinese court astronomers logged a 'guest star' in Taurus bright enough to see in daylight for nearly a month. Nearly seven centuries later John Bevis noticed a faint glow at the same spot, and Charles Messier, hunting comets, came across it and made it the first object in his list of fuzzy patches that could be mistaken for comets. Lord Rosse's 1844 drawing, which gave the filaments a claw-like look, supplied the name. In the 20th century astronomers matched the nebula's position and expansion to the Chinese records.

The pulsar at the centre

Radio astronomers picked up pulses from the direction of the Crab in 1968, and the source was soon timed at one flash every 33 milliseconds. Nothing larger than a neutron star could spin that fast without flying apart, so the Crab helped settle what pulsars are. The star is slowly braking, and the rotational energy it loses, roughly 100,000 times the Sun's power, is what keeps the whole cloud glowing, from radio waves to gamma rays.

Hubble and Webb

Hubble images taken about 25 years apart show the filaments moving outward, the outer ones farther than the inner ones, which suggests they are being pushed rather than stretched. Some filaments cast shadows on the synchrotron haze behind them while others do not, which tells astronomers which lie on the near side and helps build a three-dimensional model. Webb's infrared view adds the dust and the wisps that trace the pulsar's magnetic field.

Observing it

The Crab lies about a degree from Zeta Tauri, the star at the tip of the bull's southern horn. At magnitude 8.4 it is too faint for the naked eye; binoculars under dark skies or a small telescope show a pale oval smudge, and the filaments appear only in long-exposure photographs. For northern observers it is best placed on winter evenings, around January.

Missions

1. 1990–

   Hubble Space Telescope

   NASA / ESAActive

   Ultraviolet to near-infrared imaging from low Earth orbit.

   Mission page (opens in a new tab)

2. 2021–

   James Webb Space Telescope

   NASA / ESA / CSAActive

   Infrared observatory at Sun–Earth L2, about 1.5 million km from Earth.

   Mission page (opens in a new tab)

Related entries

• PulsarsCosmic lighthouses
• SupernovaeHow stars explode

Sources

1. Comella et al. 1969, Nature 221:453 (Crab pulsar period) (opens in a new tab)
2. ESA: ESA/Hubble heic2607: the Crab Nebula (opens in a new tab)
3. Chandra: Crab Nebula (opens in a new tab)
4. NASA Science: Hubble Messier catalog: M1 (opens in a new tab)

Last reviewed 10 Oct 2026 against these sources. Built from public NASA, ESA and JPL data; not affiliated with or endorsed by any agency.