- English name:
- see Stellar data
M 42 (Large Orion Nebula),
M 43 (De Mairan Nebula)
- Binaries beta Ori, delta Ori, zeta Ori, eta Ori, theta1 Ori, theta2
Ori, iota Ori, lambda Ori, Struve 750, Struve 747
- Multiple star cluster sigma Ori, Struve 761
- Star cluster NGC 1981
- Irregularly variable star alpha Ori
- Meteor Showers:
A constellation, which is the head of a constellation family, located
in the equatorial region of the sky and belongs certainly to the most famous
constellations. It extends from RA=4h 40m to RA=6h 20m and DECL=+23 degrees to
In some ways the central part of this constellation reminds on a oblique
sand-glass. In wintertime Orion is a magnificent constellation which can
easily be found by the the three stars forming a line building the belt
of the Hunter (these stars are sometimes called Jacob's Ladder or
The belt stars point towards Sirius, the brightest star in the constellation
of the Larger Dog, Canis
Maioris, situated SE of Orion.
From his belt there hangs a well defined dagger (known as "Sword of Orion"), which is known for one
of the most famous nebulas in the sky: The
Large Orion Nebula (M42).
Orion lies close enough to the Milky Way to be interesting enough to be swept
even with low-power telescopes or binoculars.
Additionally to the data given above there is a
skychart to locate the stars and objects.
Stars and objects
The shoulder star alpha Ori,
Betelgeuse, is a variable
red giant; its brightness varies from 0.4 mag to 1.3 mag with no set period.
It belong to the 20 brightest
stars in the sky. During it pulsations the diameter of the star varies
from 300 to 400 times the diameter of the sun. The name is traced back to
a spelling error. Orginally the star was called iad el jauza: the
hand of the giant.
The leg of the hunter, beta Ori, Rigel (arab.: the foot),
is a blue-white giant of 0.08 mag. This makes it the sixth brightest star in
the sky and the brightest in the constellation Orion. With medium sized
telescopes it is possible to distinguish the companion of Rigel, a 7th mag
star (smaller telescopes may fail to reveal the companion because of the glare
This constellation offers a great number of binaries and multiple stars:
For binoculars and smaller telescopes the following stars are of interest:
Next to it lies theta2 Ori, a duo of a 5th and a 6th mag star.
- delta Ori, Mintaka (arab.: upper end of the
girdle), a blue-white star of 2.2 mag with a 7th mag companion.
- iota Ori, a 3rd mag and a 7th mag star forming an unequal double;
in the same field the wider double
- Struve 747 can be found - a pair of a 5th mag and a 6th mag star.
- lamba Ori, a tight pair of 4th and 6th mag stars.
- sigma Ori is a terrific multiple star; in binoculars this
blue-white star of 4 mag and a 7th mag companion can be resolved; using a small
telescope two closer companions of 7th mag and 10th mag are revealed. These
stars are grouped in a way that they look like a planet with moons.
- If the resolution is not too high in the same telescopic field as sigma
Ori the triple star Struve 761 can be seen. It consists of a triangle
of 8th mag and 9th mag stars. Together with sigma Ori this triple star
gives a delightfully rich grouping.
- NGC 1981, a little cluster of 10 stars including the binary
Struve 750, a pair of a 6th mag and a 8th mag star.
- The multiple star theta1 Ori, the northern star of the dagger of the
Hunter is also called the Trapezium; it is located in the heart
of the Orion nebula. This group of stars has been formed from the gas of the
nebula, which now glows in their light. Small telecopes (about 2-inch and
higher) show four stars, ranging from 5th mag to 8th mag, which form a
rectangular figure. Scopes with an aperture of about 100 mm show two more
stars of 11th mag in this group.
For resolving the tight double of zeta Ori (Alnitak) in its consisting
parts, a bright star of 2.02 mag and a 4th mag companion, scopes with an
apertur of at least 75mm and a high resolution are required. Further more there
is a wider companion of 10th mag.
Eta Ori is a difficult pair. Scopes with an aperture of 100 mm and
higher are necessary to split it into its 4th mag and 5th mag stars.
The constellation Orion became most famous for its nebula. The Messier database
has detailed information about The Large Orion Nebula
M 42 and
M 43, the DeMairan nebula, which is a
part of the Orion Nebula.
Around October 21 each year the famous
Orionid meteor shower reaches
Coming from the the border to the constellation gemini as much as 20 meteors
per hour can be seen. More information about this meteor shower and the
Chi Orionids, which
are active around the beginning of december can be found in the meteor shower
calendar by Gary Kronk. (Readers in the US might use the
of Gary Kronk).
According to greek mythology Orion died being stung by a scorpion.
He is set such in the sky that he sets in the west while his slayer,
raises in the east.
Followed by his two dogs he is now fighting the bull
According to Secrets of the Night Sky (Bob Berman, William Morrow &Co,
1995) the ancient Sumerians saw in this star pattern a sheep and called
that star armpit of the sheep.
C. Kronberg --- 28.12.2005 ---
smil (at) clell.de