Expert: Jayendra Upadhye - 8/29/2004

Question
how can we define a NEBULA.And also tell me about lagoon nebula

Answer
Hi Omer,
If uou have access to google, just type
define:Nebula
into the "search" pane.
You will get a number of sites with complete definitions.
Nebula is a general type, with particulars such as
1 - refelection nebula
2 - emission nebula
3 - planetary nebula
4 - solar nebula etc..
all these you will find at :-
http://www.google.com/search?hl=en&ie=ISO-8859-1&q=define%3Anebula
The lagoon nebula has been catalogued as M8 (MESSIER CALATALOG) and is near the triffid Nebula.
Le Gentil found the nebula in 1747.
Lagoon Nebula has an apparent extension of 90x40 minutes of arc, which is 3 x 1 1/3 the apparent diameter of the full moon, and corresponds to about 140x60 light years if our distance of 5,200 light years should be correct, which is a bit uncertain; newer sources have 4850 (Glyn Jones) to 6500, but David J. Eichler gives the value of 5,200 light years.
The hourglass nebula is part of the lagoon nebula.
The lagoon also has a number of proto stars forming inside their "cacoons" which are dark globules called Burnham globules. These globules are rougly 10000 Astronomical units in dia. (1 Astronomical unit = mean distance between the Earth and the Sun = 93 million miles or 150 million Km).
Lastly, The lagoon is located in Sagittarius, which is the direction pointing to the galactic center.
The site:-
http://www.seds.org/messier/m/m008.html
covers the lagoon nebula comprehensively.
Jayen.