In March the observers in the Northern Hemisphere are saying goodbye to our favourite winter constellation Orion. But before the Great Hunter disappears from the view until the next Autumn, let’s take a close look at the stars that make up the famous hourglass shape. Note: we will describe Orion as we see it from the Northern Hemisphere. Observers in the Southern Hemisphere will see Orion mirrored and upside down.

1. Orion up close

2. Left shoulder….Betelgeuse
Alpha Orionis is commonly known as Betelgeuse, which means the “underarm of
Orion” in Arabic. It is a very famous and well studied star. Betelgeuse is a Red
Supergiant more then 900 times the size of our Sun. And not just any supergiant,
but the closest one to the Earth. One day Alpha Orionis will explode as
supernova, and when that happens, the star will be visible in the daytime for a
few weeks.The Boom can happen any moment in the next million years. But
don’t worry, we will be watching the spectacular show from a safe distance of
about 640 light years. It will cause no harm to the Earth and its inhabitants
whatsoever. Phew!
Betelgeuse is known to change its brightness over time in a complicated pattern.
The stars that behave this way are called semiregular variables. Modern
astronomers were not the first to discover the variability of Alpha Orionis.
Researchers think that Aboriginal Australians already knew about and observed
the changes in its brightness!
Although Betelgeuse is a single star, some astronomers think that it used to have
a stellar companion that the star swallowed when it swelled up as a Supergiant.
This could have explained the unusually fast rotation of Alpha Orionis.
Everything about Betelgeuse is a bit of a mystery: its size, distance to the Earth
and even how much time it’s got left. But that’s part of what makes this star so
interesting to the researchers and observers all over the World!

3. Right shoulder…Bellatrix
Designated Gamma Orionis, Bellatrix (meaning “female
warrior” in Latin) is a single blue-white star 4 times hotter
and 6 times bigger than the Sun. Scientists think that
Bellatrix is aging, and possibly has already evolved into
what we call a Giant star. Just like Betelgeuse, Bellatrix
changes its brightness over time, so it is too classified as
a variable star. Gamma Orionis is the closest of the seven
famous Orion stars to the Earth.

4. Head…Meissa
Faint star Lambda Orionis, or Meissa, marks the head of
the Great Hunter Orion. If you point a small telescope at
Meissa, you will be surprised to discover that it is actually
a pair of hot blue-white stars: a giant and a main
sequence star. It might have had another stellar
companion in the past that has already exploded as a
supernova.
Left foot…Saiph
White-Blue Supergiant Saiph ( Kappa Orionis) marks
Orion’s left foot. The name of the star can be loosely
translated as “sword of a giant” from Arabic.
Approximately the same distance from the Sun as
Betelgeuse, Saiph will share the fate of other red
supergiants and explode as a supernova one day. But,
again, don’t panic, we will be quite safe here on Earth!

5. Right foot… Rigel
Another future Supernova, the Blue Supergiant Rigel,
outshines all the other stars in Orion. It should have been
designated Alpha Orionis, but because the variable star
Betelgeuse happened to be at its brightest at the time the
stars were cataloged, Rigel got only a second “Beta”
place. Although invisible to the unaided eye, Rigel has
three companions, making Beta Orionis a quadruple star
system.
Orion’s Belt
Orion is very easy to find on the sky thanks to the three
stars, Alnitak, Alnilam and Mintaka, that form “Orion’s
belt”. The stars appear to be about the same size and
distance from each other and make a nearly straight line.
Some people believe that the three stars in the Belt align
with the three main pyramids in Giza. But the arguments
against this so-called Orion correlation theory (though it
does sound absolutely beautiful) look quite strong.

6. Alnitak (left)
For the past few centuries observers knew that what looks
like a star marking the left side of the Hunter’s belt is
actually a binary system: a blue supergiant with its smaller
blue companion. But more recent observations revealed
another blue subgiant located close to the primary star. It
turns out that Alnitak (designated Zeta Orionis) is a triple
star system.
Alnilam (middle)
The brightest star in the Belt and the most distant one is
Epsilon Orionis, or Alnilam. This hot and luminous blue
supergiant is over 30 times as as big as the Sun. Just like
any other star of this kind, Alnilam will one day turn into
red supergiant and eventually explode as supernova.

7. Mintaka (right)
Another example of a multiple star system is a Blue
Supergiant Mintaka (aka Delta Orionis). The star system
consists of a main triple star component (two very hot
stars orbiting close together and the third star further
away) and one or two single stars (researchers are not
sure whether one of the stars is part of Mintaka system or
a background star).

8. Still curious?
•Visit our pop-up planetarium to learn more about the
night sky, constellations, famous stars and other amazing
celestial objects.
•Send your questions and comments to our star
dome team. We would love to hear from you!
•Read more astronomy news in our space blog.
Happy stargazing!