ORION
The above is an image taken by Andy Atterbury of the constellation of Orion using a Canon 500 DSLR and fitted with a Sigma Zoom lens. ISO setting of 800 and 1 minute guided exposure.
Orion is the most prominent constellation of the Winter Skies. In mythology it represented the Hunter. The image has the main stars of this constellation labelled.
Both Betelgeux and Rigel are first magnitude stars. Rigel is an extremely hot star of spectral type B. and is therefore extremely luminous too; it is 60,000 times more luminous than our Sun. It has been measured to be approximately 900 light years distant from us. All this means is that it has taken light from this star 900 years to reach our eyes when we look at it in the night sky. The speed of light is 186,000 miles per second, so this does give you some idea of how far away some of these stars are from us. To calculate this distance in miles it is 186,000 miles x 60 Seconds x 60 Minutes x 24 Hours x 365 days x 900 years. I won’t work this out, but you can see that this would produce a very big number, which is why astronomers tend to speak in terms of light years rather than miles or kilometres when they are talking about distances in terms of the stars and that of the galaxies.
At the opposite end of Orion is Betelgeux. The surface temperature is lower than that of the Sun at 3400 degrees Celsius (the surface of the Sun is 6000 degrees), but Betelgeux is huge; it is a vast Supergiant star. If it was to be placed where our Sun is, at the centre of our Solar System it would easily contain the Earth’s orbit within its volume. Betelguex is an evolved star and it has used up much of its reserves of hydrogen fuel, which would have caused its core temperature to increase dramatically and as a consequence the star has become distended to form this red Supergiant. Its outer layers are extremely rarefied and have been estimated to be 10 thousand times more rarefied than the Earth’s atmosphere at sea level. Betelguex is extremely unstable and is a prime candidate for this star to go Supernova. Nobody knows when this will happen. It could have already have happened of course. This is because, if Betelgeux did explode now, it would still take 520 years for us to find out about this, as it takes the light from this star that long to reach us.
The most obvious feature of Orion, are the three stars that make up the Belt of Orion. From left to right these are Alnitak, Alnilam and Mintaka. If you follow the belt down from Alnitak, then the group of stars here make up Orion’s Sword and within this is situated M42 (Messier 42), the Great Orion Nebula. This has picked out well in the image. M42 is a place where stars are being born; often termed ‘a stellar nursery’. The nebula is easily visible in binoculars and through a telescope on low power it is quite magnificent. As with all these deep sky objects the darker the sky the better the view. For me the nebula often seems to have a greenish hue; to others all they say they can see is white light, but any camera digital or film always respond to the hydrogen light and it appears mostly red in images.
The Hubble Space Telescope has been able to image regions of the Great Nebula where stellar birth is taking place and some of these objects show disc like structures. These are believed to be places where planetary formation is taking place, similar to the situation envisaged by scientists for the formation of the Earth and planets some 4.6 billion years ago. In the centre of the Orion nebula, embedded in the nebula, if you look at this through a telescope you will see the famous Trapezium of stars. Even small telescopes will resolve these into 4 separate stars. These stars are very young and extremely hot, heating up the gas from within the nebula, and this is responsible for causing the cloud to glow.
Orion is the most prominent constellation of the Winter Skies. In mythology it represented the Hunter. The image has the main stars of this constellation labelled.
Both Betelgeux and Rigel are first magnitude stars. Rigel is an extremely hot star of spectral type B. and is therefore extremely luminous too; it is 60,000 times more luminous than our Sun. It has been measured to be approximately 900 light years distant from us. All this means is that it has taken light from this star 900 years to reach our eyes when we look at it in the night sky. The speed of light is 186,000 miles per second, so this does give you some idea of how far away some of these stars are from us. To calculate this distance in miles it is 186,000 miles x 60 Seconds x 60 Minutes x 24 Hours x 365 days x 900 years. I won’t work this out, but you can see that this would produce a very big number, which is why astronomers tend to speak in terms of light years rather than miles or kilometres when they are talking about distances in terms of the stars and that of the galaxies.
At the opposite end of Orion is Betelgeux. The surface temperature is lower than that of the Sun at 3400 degrees Celsius (the surface of the Sun is 6000 degrees), but Betelgeux is huge; it is a vast Supergiant star. If it was to be placed where our Sun is, at the centre of our Solar System it would easily contain the Earth’s orbit within its volume. Betelguex is an evolved star and it has used up much of its reserves of hydrogen fuel, which would have caused its core temperature to increase dramatically and as a consequence the star has become distended to form this red Supergiant. Its outer layers are extremely rarefied and have been estimated to be 10 thousand times more rarefied than the Earth’s atmosphere at sea level. Betelguex is extremely unstable and is a prime candidate for this star to go Supernova. Nobody knows when this will happen. It could have already have happened of course. This is because, if Betelgeux did explode now, it would still take 520 years for us to find out about this, as it takes the light from this star that long to reach us.
The most obvious feature of Orion, are the three stars that make up the Belt of Orion. From left to right these are Alnitak, Alnilam and Mintaka. If you follow the belt down from Alnitak, then the group of stars here make up Orion’s Sword and within this is situated M42 (Messier 42), the Great Orion Nebula. This has picked out well in the image. M42 is a place where stars are being born; often termed ‘a stellar nursery’. The nebula is easily visible in binoculars and through a telescope on low power it is quite magnificent. As with all these deep sky objects the darker the sky the better the view. For me the nebula often seems to have a greenish hue; to others all they say they can see is white light, but any camera digital or film always respond to the hydrogen light and it appears mostly red in images.
The Hubble Space Telescope has been able to image regions of the Great Nebula where stellar birth is taking place and some of these objects show disc like structures. These are believed to be places where planetary formation is taking place, similar to the situation envisaged by scientists for the formation of the Earth and planets some 4.6 billion years ago. In the centre of the Orion nebula, embedded in the nebula, if you look at this through a telescope you will see the famous Trapezium of stars. Even small telescopes will resolve these into 4 separate stars. These stars are very young and extremely hot, heating up the gas from within the nebula, and this is responsible for causing the cloud to glow.
Above is another image by Andy, and is a stack of 3 x 1 minute exposures. If you look at the bottom star of the belt; Alnitak or Zeta Orionis, you may just be able to make out some red nebulosity to the left of this star. This is the Flame Nebula or NGC 2024. It is a cloud of hot gas that is bisected by a foreground lane of dust. You can just see this lane if you look hard at the image.
