Nebula possibly discovered 1610 by Nicholas-Claude Fabri de Peiresc.
Independently found by Johann Baptist Cysatus in 1611.
Trapezium cluster found as multiple star by Galileo Galilei in 1617.
The Orion Nebula Messier 42 (M42, NGC 1976) is the brightest
starforming, and the brightest diffuse nebula in the sky, and also one
of the brightest deepsky objects at all. Shining with the brightness of
a star of 4th magnitude, it visible to the naked eye under moderately
good conditions, and rewarding in telescopes of every size, from the
smallest glasses to the greatest Earth-bound observatories as well as
outer-space observatories like the Hubble Space Telescope. It is also a
big object in the sky, extending to over 1 degree in diameter,
thus covering more than four times the area of the Full Moon.
As it is so well visible to the naked eye, one may wonder why its
nebulous nature was apparently not documented before the invention of
the telescope. Only some Central American, Mayan folk tales may be
interpreted in a way suggesting that these native Americans may have
known of this nebulous object in the sky (O'Dell
2003, p. 3). However, the brightest stars within the nebula were
noted early and cataloged as one bright star of about fifth magnitude:
In about 130 AD,
Ptolemy
included it in his catalog, as did
Tycho Brahe
in the late 16th century, and
Johann Bayer
in 1603 - the latter cataloging it as Theta Orion in his Uranometria.
In 1610,
Galileo detected a number of faint stars when first looking at this
region with his telescope, but didn't note the nebula. Some years later,
on February 4, 1617, Galileo took a closer look at the main star,
Theta1, and found it to be triple, at his magnification of 27 or 28x,
again not perceiving the nebula.
The Orion Nebula was probably discovered in late 1610, when
Nicholas-Claude
Fabri de Peiresc (1580-1637), a French lawyer, turned his telescope
to this region of the sky, and reported of a cloudy nebulosity. This
sighting, however, was not published, but only reported in Peiresc's
personal documents and brought up only by
Bigourdan (1916). It was independently found in 1611 by the Jesuit
astronomer
Johann Baptist Cysatus (1588-1657) of Lucerne who compared it to a
comet he had observed in the year 1618 (Cysat 1619).
This work also did not get widely known, and openly turned up by Rudolf
Wolf in 1854 (Wolf 1854). The
first known
drawing of the Orion nebula was created by
Giovanni
Batista Hodierna, who included three stars; these are probably
Theta1 as well as Theta2A and Theta2B. All these discoveries apparently
got lost for some
time, so that eventually
Christian
Huygens was longly credited for his independent rediscovery in 1656,
e.g. by Edmond
Halley who included it in his
list of six
"nebulae" (Halley 1716), by
Jean-Jacques
d'Ortous de Mairan in his
nebulae
descriptions, by
Philippe
Loys de Chéseaux in
his list,
by Guillaume
Legentil in his review, and by
Charles
Messier when he
added it
to his catalog on March 4, 1769.
It is somewhat unusual that the Orion Nebula has found its way into
Messier's list,
together with the bright star clusters
Praesepe M44 and the
Pleiades M45; Charles
Messier usually only included fainter objects which could be easily
taken for comets. But in this one night of March 4, 1769, he determined
the positions of these well known objects, (to say it with Owen
Gingerich) `evidently adding these as "frosting" to bring the list to
45', for its first publication in the Memoires de l'Academie for
1771 (published 1774).
One may
speculate why he prefered a list of 45 entries over one with 41; a
possible reason may be that he wanted to beat
Lacaille's
1755 catalog of southern objects, which had 42 entries. Messier
measured an extra position for a smaller northeastern portion, reported
by
Jean-Jacques d'Ortous de Mairan previously in 1731 as a separate
nebula, which therefore since has the extra Messier number:
M43.
As the drawings of the Orion Nebula known to him did so poorly
represent Messier's impression, he created a
fine
drawing of this Object, in order to "help to recognize it again,
provided that it is not subject to change with time" (as Messier states
in the
introduction to his catalog).
This gorgeous object continued to influence astronomers since. It was
the first deepsky observation by
William
Herschel with a self-constructed reflecting telescope of 6-foot
focal length in 1774. In 1789, with some prophetic touch, he described
his observations with his 48-inch aperture, 40-foot FL scope as "an
unformed fiery mist, the chaotic material of future suns."
The gaseous nature of the Orion Nebula was revealed in 1865 with the
help of spectroscopy by
William Huggins.
On September 30, 1880, M42 was the first nebula to be successfully
photographed, by
Henry Draper. Consequently, on March 14, 1882, Henry Draper obtained
a second, better, deeper, and more detailed photograph of the Orion
Nebula, a 137-minutes exposure, which also clearly shows M43.
The Orion Nebula is located at a distance of about 1,600 (or perhaps
1,500) light-years. At this distance, its angular diameter of 66x60 arc
minutes corresponds to a linear diameter of about 30 light-years. On its
northern end, the nebula is divided by a conspicuous dark lane, well
visible in our photograph. This image was obtained David Malin of the
Anglo-Australian Observatory.
More information
on this image is available.
The detached northeastern portion is the nebula
M43 first reported by
De Mairan, and listed as a separate nebula by Charles Messier. Like the
main nebula M42, this is an emission nebula, shining by the light
emitted from its atoms, after being excited by the high-energy radiation
of massive, very hot young stars within it. In the very neighborhood, to
the north, there are also fainter reflection nebulae, partially
reflecting the light of the Great Nebula. They were not notable for
Charles Messier, but labeled later with the NGC numbers 1973, 1975, and
1977: NGC 1977 had been found by William Herschel (his H V.30), while
NGC 1973 and NGC 1975 are discoveries of
Heinrich
Ludwig d'Arrest. Here we have a collection of
more images of
M42, M43, and
more images of
M42, M43 and NGC 1973-5-7.
The Orion Nebula is the brightest and most conspicuous part of a
much larger cloud
of gas and dust which extends over 10 degrees well over half the
constellation Orion. The linear extend of this giant cloud is well
several hundreds of light-years. It can be visualized by long exposure
photos (see e.g. Burnham) and contains, besides the Orion nebula near
its center, the following objects, often famous on their own:
Barnard's Loop,
the Horsehead
Nebula region (also containing NGC 2024 = Orion B), and the
reflection nebulae around
M78. Already impressive in deep visible light photographs, the Orion
Cloud is particularly gorgeous in the
infrared light.
M42 itself is apparently a very turbulent cloud of gas and dust, full
of interesting details, which Charles Robert O'Dell has compared to the
rich topography of the Grand Canyon in his HST photo caption. The major
features got names on their own by various observers: The dark nebula
forming the lane separating M43 from the main nebula extends well into
the latter, forming a feature generally nicknamed the "Fish's Mouth".
The bright regions to both sides are called the "wings", while at the
end of the Fish's Mouth there's a cluster of newly formed stars, called
the "Trapezium
cluster". The wing extension to the south on the east (lower
left in our image) is called "The Sword", the bright nebulosity below
the Trapezium "The Thrust" and the fainter western (right) extension
"The Sail". Here we have a small collection of
Images of detail
in M42, including another nomenclature for the brightest region in
the nebula by historic visual observers, as well as a pictorial study of
the Trapezium
cluster and region by Lowell Observatory images.
The
Trapezium Cluster is among the very youngest (open) clusters known,
with new stars still forming in this region. As stated above, the
cluster was first depicted as triple star on February 4, 1617 by
Galileo,
who was not aware of the nebula. Galileo's discovery did not get widely
known, so that Christian Huygens independently rediscovered the triple
star in 1656 together with the Orion Nebula. These first three stars are
often labeled "A", "C", and "D". It may be of interest that in both
cases, the Trapezium, or Theta1 Orionis, was second to only one other
double star:
Mizar
(Zeta Ursae Majoris). The fourth Trapezium star, "B", was first
found by Abbé
Jean Picard in 1673 (according to De Mairan), and independently by
Huygens in 1684. The fifth cluster star "E" was discovered by
Friedrich Georg
Wilhelm Struve in 1826 with a 9.5-inch refractor in Dorpat, the
sixth, "F", by
John Herschel
on February 13, 1830, the seventh, "G", by Alvan Clark in 1888 when
testing his 36-inch refractor of Lick Observatory, and the eighth, "H"
by E.E. Barnard
later in 1888 with the same telescope. Barnard later found that "H" is
double, with two 16th-magnitude components. Today we know that stars "A"
and "B" are both eclipsing variables of Algol type: A (also known as
V1016 Ori) was discovered in 1975 to vary between magnitudes 6.73 and
7.53 with a period of 65.4325 days, while B (also cataloged as BM Ori)
varies between mag 7.95 and 8.52 in 6.4705 days, and is always the
faintest of the four Trapezium stars.
The past decades of research on the Orion Nebula have revealed that
the visible nebula, M42, the blister of hot, photo-ionized, luminous gas
around hot Trapezium stars, is only a thin layer lying on the surface of
a much larger cloud of denser matter, the Orion Molecular Cloud 1 (OMC
1). We happen to see this structure approximately face-on. The idea for
this model came originally from Münch (1958)
and Wurm (1961) and fully elaborated by several
authors around 1973-1974 (Zuckerman (1973),
Balick et.al. (1974)), soon supported
by evidence, and is still studied in detail, see e.g.
O'Dell (2001) for a recent review, and
references cited therein. The San Diego
Supercomputer Center (SDSC)'s VisLab has created a
3-dimensional
visualization of the Orion Nebula based on this model (see
side-view model image of M42).
The Orion nebula was, continuously since the
early times
before its refurbishment, a preferred target for the Hubble Space
Telescope. One major discovery was that of protoplanetary disks, the so
called "Proplyds" (planetary systems in formation) in these
HST images of M42
(these images were used for an
animation
simulating the approach to a protostar
[caption]).
HST images of
November 1995 have revealed further insight into the complicated
process taking place in this "star factory".
Hubble
investigations of January 1997 have revealed interesting
interactions of the young hot Trapezium cluster stars with the
protoplanetary disks: Their violent radiation tends to destruct the
discs, so that the lower-mass stars forming here may loose the material
needed to form planetary systems.
In 1982, a symposium solely devoted to the Orion Nebula was held to
celebrate New York University#s Sesquicentennial, and to honor the one
hundredth anniversary of the first photograph of the Orion Nebula taken
by Henry Draper on September 30, 1880 (Glassgold
et.al. 1982).
An excellent review of the astrophysics of the Orion Nebula is
provided in 2003 with the superb monograph by Charles Robert O'Dell (O'Dell
2003), who summarizes the knowledge of that time, including HST
research.
It is very easy to find the Orion Nebula, as it surrounds the Theta
Orionis multiple star or cluster, seen to the naked eye in the middle of
the sword of Orion. Already under fairly good conditions, the nebula
itself can be glimpsed with the naked eye as a faint nebulosity around
this star.
The Orion Nebula is also one of the easiest and most rewarding target
for amateur
astrophotographers.
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