M8 - Lagoon Nebula

Messier 8 or M8 (also designated NGC 6523) is a nebula and star cluster in the constellation Sagittarius. It has an apparent visual magnitude of 6 and its angular diameter is 90x40 arc-minutes. M8 lies at an estimated distance of 5200 light years. The Equinox 2000 coordinates are RA= 18h 03.8m, Dec= -24° 23´ which makes M8 best seen during the summer. The Messier Summer Star Chart shows the position of all Messier objects visible during that season. As one of the more famous objects in the Messier Catalog, it is commonly known as the Lagoon Nebula.

The image above shows the uncropped view of M8 through the Takahashi E-180 Astrograph (North is up). A 2x enlargement of this image appears to the right.

For a higher power view of this object using the ASA N12 Corrected Newtonian Astrograph, see M8 (ASA N12).

The Lagoon Nebula contains a number of interesting objects known as Bok globules, These are dark, collapsing clouds of protostellar material, many of which were catalogued by E. E. Barnard. A tornado-like structure is associated with one of the hot O-type stars due to the ultraviolet radiation it emmits. The Hourglass Nebula is another unique structure that lies at the center of M8 where star formation is presently in progress.

In spite of its inclusion in the Messier Catalog, this diffuse nebula and star cluster were actually discovered by J. Flamsteed in 1680. According to Kharchenko et al. (2005), the distance of M8 is 4310 light years and its diameter is 9 light years. It contains over 130 stars and its estimated age is 2.3 million years.

For more information, see the Messier Catalog as well as specific entries for M8 in Wikipedia and SEDS.

Messier's Description of M8

May 23, 1764
`A cluster which appears in the shape of a nebula when observed with an simple refractor of 3 feet; but with an excellent instrument one perceives nothing but a large quantity of small [faint] stars; near this cluster is a fairly bright star, surrounded by a very faint glow: this is the ninth star of Sagittarius, of seventh magnitude, according to Flamsteed [9 Sgr]: this cluster appears in elongated shape, which extends from North-East to South-West, between the arc of Sagittarius and the foot of Ophiuchus. (Diam. 30')'

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