continued from Starlit Sky: 3. Solar system


Look westwards on an April night at around 9 pm IST. You can clearly see a cluster of stars in the form given here. 4 bright stars in 4 corners, with 3 stars in the middle in a line, and another 3 fainter stars in a line below the three in the middle. If you club all these stars together then it is possible to imagine a hunter. This is the Orion constellation, named after the word hunter in Greek. It is called the kalapurusha mandala in sanskrit.


orion 2

λ (lamda) stars are the head of the hunter. α (alpha), and γ (gamma) stars are his shoulders, β (beta) and κ (kappa) stars are his legs, ε (epsilon) stars are his belt, ι (iota) stars represent the sword hanging from his belt.

Lets now learn more about each of the stars in this constellation.

α orionis : This is the second brightest star in this constellation. It is also called Betelgeuse. It is called “Ardra” star in the Indian astronomical star system. It is a massive red supergiant star.

It is a slightly red, with apparent brightness of 1, is approximately 643 light years away. A light year is the distance traveled by light in a year at a speed of 3,00,000 kms/sec. This means that the light that you see now from α (alpha) is the light that started traveling in space about 643 years ago!

In astronomical sense, Betelgeuse is nearing the end of its life. Now it has reached the red supergiant stage.

That is the last stage of a star’s life. Then a red giant will explode and spew its contents all over space. When this supergiant Betelgeuse will explode several million centuries later, it will be seen even in the daytime! How awesome would that be!!

β orionis : This is also called Rigel. It is a blue supergiant star. With apparent brightness of 1, it is the 6th brightest star in the sky. It shines with a slight blueish colour and it is at a distance of about 772 light years away.

γ orionis: γ orionis forms the other shoulder of the hunter. It is also called Bellatrix and also “Amazon star”. It has a brightness of 1 and is the 27th brightest star in the night sky. It is a blue giant, but it is too small to become a supernova. It is about 243 light years away.

λ orionis: 3 star cluster making a small triangle mark the head of the hunter. The center one is a hot blue giant and about 1100 light years away. Phi-1, and Phi-2 make the base of λ orionis.

The brightest among the three is called the “Mrigashira” star in the Indian astronomical star system.

ε orionis: The 3 stars that form the belt of the hunter are called ε orionis. They are of similar brightness of 3. They are used as navigational aids in finding direction too. Using this belt, we can locate other stars in the sky.

κ orionis: This star forms the right foot of the hunter. It is also called Saiph. It is of similar size and distance to Rigel, but it appears fainter because most of its light travels in the ultraviolet range of the spectrum.

ι orionis: The three faint stars that are seen below the belt stars are the ι stars. These form the sword of the hunter. The middle star of this sword is not actually a star but a nebula. It is called the Orion nebula.

Random gyaan:

A nebula is a cloud of dust, hydrogen, helium and other ionised gases, that are yet to come together to form a star. These gases revolve around a center core.


The orion constellation can be seen in the winter sky of the Northern hemisphere from november to april.

to be continued…………..