The Crab Nebula is the most famous and conspicuous supernova remnant in our night sky.

Around the year 5246BC a star in the constellation of Taurus exploded, about 6,300 light years from Earth. The explosion was eventually observed in 1054AD as a very bright supernova, which today has developed as the Crab Nebula. It shines as a nebula of magnitude 8.4 near the southern "horn" of Taurus.

The Crab Nebula can easily be seen under clear dark skies, but can equally easily be lost in background light under less favourable conditions. With 7x50 or 10x50 binoculars, M1 is just visible as a dim patch. With a little more magnification, it is seen as a nebulous oval patch, surrounded by haze. In telescopes starting with a 4-inch aperture, some detail in its shape becomes apparent, with mottled patches and streaks towards the inner part. Messier's impression was that M1 looks similar to a faint comet without a tail in smaller instruments. Under excellent conditions and with larger telescopes, from about 16 inches aperture, suggestions of the filaments and fine structure become visible.

M2 is a difficult object for naked-eye observation and is not visible under normal conditions.

With binoculars it is an easy target as it is situated in a star-poor area. A 4-inch telescope only shows some of the brightest member stars spread over a mottled nebulous background caused by unresolved stars. However, with a 4-inch refractor, it is possible to see a dark curved feature crossing the north-eastern corner of the cluster. With an 8-inch telescope under good conditions, the cluster is partly resolved into stars. Larger telescopes, from 10-inch, are required to fully resolve the cluster and dark regions.

M3 contains an estimated half a million stars and is visible to the naked eye under very good conditions. It is just below the limit of visibility under average conditions.

With binoculars, it appears as a hazy, nebulous patch. A 4-inch telescope shows a bright compact core within a round, mottled, grainy glow, which uniformly fades towards the outer edges. A 4-inch does not resolve the cluster but, under good conditions, shows some of the brightest stars. A 6-inch telescope resolves the outer two thirds into faint stars with a background glow of unresolved fainter stars. An 8-inch shows stars throughout the cluster except in the core, which is resolved by telescopes of 12 inches upwards.

M4 can be easily found at 1.3º west of the bright star Antares, magnitude 1 in Scorpio. Through binoculars M4 appears as a round diffuse patch. A 4-inch telescope resolves the brightest stars of about magnitude 10.8 with an irregular distribution whilst larger telescopes show a halo of stars around the bright central portion of the cluster.

The Hubble telescope has identified at least one planet orbiting a white dwarf star in M4. These stars are among the oldest in the Milky Way, estimated at about 13 billion years old almost three times the age of our Solar System.

With good viewing conditions, M5 can just be glimpsed with the naked eye. In binoculars it is easily visible as small fuzzy patch and with a 3-inch telescope as a round "nebula" brighter toward the centre. From a 4-inch, the brightest stars of magnitude 12.2 can just be resolved forming curved patterns extending from the central part. Larger telescopes reveal a spectacular sight with thousands of stars and a few less populated gaps.