Crab Nebula (Messier 1)

Object Description

Messier 1 is one of the most striking and both historically and physically best-documented supernova remnants known. It is often referred to as the Rosetta Stone of Astronomy as it serves as a key object in understanding numerous supernovae and other phenomena.

Messier 1
Messier 1: Crab Nebula in Taurus; 500 mm Cassegrain 5800 mm f/11.4; SBIG STL11K; 60+10+10+10 min; Bernese Highlands; © 2005 Radek Chromik
Messier 1
Messier 1: Crab Nebula in Taurus; RC 500 on AOK Herkules V48 mount; FLI Proline 16803 ; -40 °C chip temperature, R/G/B unbinned: R 19×5 min, G 37×5 min, B 35×5 min, Hα 19×15 min; Son Bi Observatory, Mallorca; © 16.-20. 11. 2017 Beat Kohler, Stefan Meister, Hansjörg Wälchli

The chronicles of medieval China contain an interesting account of a «guest star» that appeared on 4 July 1054 AD near ζ Tauri. According to this report, this new star was as bright as Venus, shone in reddish-white light and could even be seen with the naked eye for 23 days during the day. This new star was still visible for two years. Similar reports and rock drawings of the crescent moon with a bright star next to it are known from other peoples, such as the Indians of North America. There are no records of this supernova in Europe, presumably because the prevailing Catholic Church in the Middle Ages did not tolerate such events. Strange, because the supernova of 1006 in the constellation Lupus was mentioned by a Swiss monk in his contemporary records. [4]

Messier 1
Messier 1: HST sequence of images of the «dancing sprite» for half a year. © ESA/Hubble & NASA [170]

The visually 8.2 mag bright nebula that emerged from this medieval supernova was first discovered by the English physicist and amateur astronomer John Bevis in 1731. Around 27 years later, when Charles Messier observed the return of Halley's Comet in 1758, he encountered the same nebula independently of Bevis. Upon seeing the diffuse nebula, which looked almost like a comet, Messier had the idea of compiling a catalog so that future astronomers would not mistake it for comets. Lord Rosse noticed the outer filament structure of the nebula for the first time in 1844 and compared it with the legs of a crab, whereupon he called M 1 Crab Nebula. Of course, none of these astronomers had any idea that this was the remnant of the 1054 supernova. [4]

Messier 1
Messier 1: Image taken with Hubble Space Telescope in 2005. © NASA, ESA, Allison Loll, Jeff Hester, Davide De Martin [214]

It was a long time before C. O. Lampland of the Lowell Observatory studied a series of photo plates from the 42 inch reflector in 1921 and noticed a movement inside the nebula. Soon he had shown that the Crab Nebula expanded slowly. The speed of expansion of the nebula varied in different ways areas, on average it is about 0.2 arcseconds per year. Since M 1 is a very irregular object, it is not very easy to determine the distance of the nebula and from this the speed of expansion and the age 5400 to 7000 light years and an enormous expansion speed of 1'800 km/s one calculated a possible age of the nebula of about 900 years. The calculated diameter of M 1 is about 10 light years. [4]

Ingenious time-lapse image of the Crab Nebula over a period of 10 years. Taken by Detlef Hartmann from his observatory on Emberger Alm in Austria. Single frames with a 440 mm Newton an SBIG ST-10 XME, AO-8. Newer version as 30 MB animated GIF on Astrobin. [248]

Later, due to this high rate of expansion, a supernova remnant was suspected, especially since the theory of supernovae and neutron stars became popular around the 1930s. Although this SNR (SuperNova Remnant) was identified with the Chinese «guest star» of 1054, the last evidence was missing - the neutron star.

In 1948 the Crab Nebula was identified as a strong radio source for the first time, and in 1963 X-rays were finally discovered with the help of an altitude rocket. The energy of the X-rays is about a hundred times more than that of the emitted visual radiation.

On the basis of numerous recordings through a polarization filter with a 200 inch reflector on Mt. Palomar, it was found in 1954 that the Crab Nebula shines with differently polarized light in different, relatively symmetrical areas. This indicated strong magnetic fields inside the nebula.

Messier 1
Messier 1: Composite of three images in polarized light from different planes. © Malin/Pasachoff/Caltech

In 1968 radio astronomers in Green Bank, West Virginia, discovered a pulsar rotating 30 times per second in the center of the Crab Nebula. The origin for these strong magnetic fields was found. A year later, at the Kitt Peak Observatory, Dr. Baade discovers that the pulsar is also visible in visual light. A supermassive star, a neutron star, the final evidence for identifying M 1 as an SNR was found. This neutron star has about 16 mag apparent brightness and about +4.5 mag absolute brightness - almost as bright as our sun in the visual spectrum and with a diameter of only 10 km. [4, 103, 113, 118, 120]

The images from the Hubble Space Telescope show that much more dynamic processes are taking place inside the Crab Nebula than previously thought. The nebula in the immediate vicinity of the pulsar changes its appearance within days. Strand-shaped structures move away from the pulsar at about half the speed of light. The pulsar itself is surrounded by a stationary halo that temporarily changes its luminous intensity. The effects of two polar jets moving along the axis of rotation around the pulsar are also visible. The most dynamic trait is a small knot that dances around in such a way that it has been nicknamed Dancing Sprite. [121, 127, 170]

Revised+Historic NGC/IC, Version 22/9, © Dr. Wolfgang Steinicke [277]
DesignationNGC 1952
Right Ascension05h 34m 31.9s
Declination+22° 00' 52"
Diameter6 × 4 arcmin
Visual magnitude8.4 mag
Metric Distance2.001 kpc
Dreyer DescriptionvB, vL, E 135° ±, vglbM, r
Identification, RemarksM 1, LBN 833, Sh2-244, CED 53, Taurus A, Crab nebula

Finder Chart

The supernova remnant of Messier's number one is located about one degree northwest of the 3.0 mag bright star ζ Tauri, which is the southern horn of Taurus. It is easy to find due to its special location. The best time to observe M 1 is September to February, when the constellation Taurus is highest at night.

Chart Crab Nebula (Messier 1)
Crab Nebula (Messier 1) in constellation Taurus. Chart created using SkySafari 6 Pro and STScI Digitized Sky Survey. [149, 160]

More Objects Nearby (±15°)


4«Burnham's Celestial Handbook: An Observer's Guide to the Universe Beyond the Solar System» by Robert Burnham; Dover Publications, Inc.; Voume I: ISBN 0-486-23567-X; Volume II: ISBN 0-486-23568-8; Volume III: ISBN 0-486-23673-0
103Rediscovering the Color of the Crab Nebula by David Malin and Jay M. Pasachoff; S&T 7/93, p.43
113Anatomy of a Crab by Wayne J. Parker; S&T 1/95, p.38
118X-raying the Crab; S&T 2/96, p.15
120Fingering the Crab; S&T 6/96, p.16
121Ripples in the Crab Nebula; S&T 8/96, p.10
127Bewegung im Krebsnebel; SuW 8-9/96, S.611
149SkySafari 6 Pro, Simulation Curriculum;
160The STScI Digitized Sky Survey;
170Crab Nebula -- The Movie; Press Release No. STScI-PRC96-22;
214Most detailed image of the Crab Nebula; (2020-12-31)
248Crab Nebula (one decade time-lapse movie) by Detlef Hartmann; (2021-01-24)
277«Historische Deep-Sky Kataloge» von Dr. Wolfgang Steinicke; (2021-02-17)