The Lagoon Nebula (catalogued as Messier 8 or M8, NGC 6523, Sharpless 25, RCW 146, and Gum 72) is a giant

interstellar cloud An interstellar cloud is generally an accumulation of gas, plasma, and dust in our and other galaxies. Put differently, an interstellar cloud is a denser-than-average region of the interstellar medium, the matter and radiation that exists in the ...

in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the earliest constellation ...

Sagittarius. It is classified as an emission nebula and as an H II region. The Lagoon Nebula was discovered by Giovanni Hodierna before 1654 and is one of only two star-forming

nebula A nebula ('cloud' or 'fog' in Latin; pl. nebulae, nebulæ or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral or molecular hydrogen and also cosmic dust. Nebulae are often star-forming regio ...

e faintly visible to the eye from mid-northern latitudes. Seen with

binoculars Binoculars or field glasses are two refracting telescopes mounted side-by-side and aligned to point in the same direction, allowing the viewer to use both eyes (binocular vision) when viewing distant objects. Most binoculars are sized to be held ...

, it appears as a distinct cloud-like patch with a definite core. Within the nebula is the

open cluster An open cluster is a type of star cluster made of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, an ...

NGC 6530.

Characteristics

The Lagoon Nebula is estimated to be between 4,000–6,000

light-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distance, astronomical distances and is equivalent to about 9.46 Orders of magnitude (numbers)#1012, trillion kilometers (), or 5.88 ...

s away from the

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's sur ...

. In the sky of Earth, it spans 90' by 40', which translates to an actual dimension of 110 by 50 light years. Like many nebulae, it appears pink in time-exposure color photos but is gray to the eye peering through

or a

telescope A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to obse ...

, human vision having poor color sensitivity at low light levels. The nebula contains a number of Bok globules (dark, collapsing clouds of protostellar material), the most prominent of which have been catalogued by

E. E. Barnard Edward Emerson Barnard (December 16, 1857 – February 6, 1923) was an American astronomer. He was commonly known as E. E. Barnard, and was recognized as a gifted observational astronomer. He is best known for his discovery of the high proper mo ...

as B88, B89 and B296. It also includes a funnel-like or

tornado A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, alt ...

-like structure caused by a hot O-type star that emanates

ultraviolet light Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiatio ...

, heating and ionizing gases on the surface of the nebula. The Lagoon Nebula also contains at its centre a structure known as the Hourglass Nebula (so named by

John Herschel Sir John Frederick William Herschel, 1st Baronet (; 7 March 1792 – 11 May 1871) was an English polymath active as a mathematician, astronomer, chemist, inventor, experimental photographer who invented the blueprint and did botanical wo ...

), which should not be confused with the better known

Engraved Hourglass Nebula The Engraved Hourglass Nebula (also known as MyCn 18) is a young planetary nebula in the southern constellation Musca. It was discovered by Annie Jump Cannon and Margaret W. Mayall during their work on an extended Henry Draper Catalogue (the ...

in the constellation of

Musca Musca () is a small constellation in the deep southern sky. It was one of 12 constellations created by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman, and it first appeared on a celestial globe in d ...

. In 2006, four Herbig–Haro objects were detected within the Hourglass, providing direct evidence of active

star formation Star formation is the process by which dense regions within molecular clouds in The "medium" is present further soon.-->interstellar space

by accretion within it.

Image Gallery

File:Lagoon and Trifid from Los Angeles .jpg, Lagoon and

Trifid Trifid is Latin for "split into three parts" or "threefold" and may refer to: * ''Trifid'' (journal), a Czech-language periodical * Trifid Nebula in the constellation Sagittarius * Trifid cipher, a fractionated cipher * Trifid (software), suite of ...

nebulae File:Lagoon Nebula.jpg, Image combined through three different filters (B, V, R) with a 1.5-metre telescope File:M8 Lagoon Nebula from the Mount Lemmon SkyCenter Schulman Telescope courtesy Adam Block.jpg, Center of the Lagoon Nebula

References

External links

Breaking Waves in the Stellar Lagoon
— ESA/ Hubble Photo Release
Messier 8, SEDS Messier pages

NightSkyInfo.com – M8, the Lagoon Nebula

Messier 8, Lagoon Nebula, Map

Astronomy Picture of the Day (APOD): Lagoon Nebula

(

Astronomy Picture of the Day Astronomy Picture of the Day (APOD) is a website provided by NASA and Michigan Technological University (MTU). According to the website, "Each day a different image or photograph of our universe is featured, along with a brief explanation wr ...

2012 March 12) *
Lagoon Nebula (M8) on Constellation Guide

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Characteristics

See also

Image Gallery

References

External links