Orion’s Many Colours - part 1

As the bright stars of the winter sky rise in the east, we witness a great mythological battle that has been raging for thousands of years. With his mighty shield and raised club, Orion the Hunter has been locked in this imaginary confrontation with Taurus the Bull. The constellation Orion is one of the most iconic groupings of distant suns.

It is truly amazing seeing the majestic lineup of the three sparkling belt stars (which the ancient pyramids were oriented to) and the star-forming region called the Orion Nebula. Aka M42 is found in the imaginary sword hanging from Orion’s belt. Alone they are impressive to the naked eye but the magic of astrophotography reveals the true colours of this amazing region of space.

We first start with the Orion Nebula. Located 1,500 light-years away, M42 is a stellar nursery that spans about 25 light-years across and is condensing and compressing individual pockets of gas and dust to form thousands of new stars. The Hubble Space Telescope has imaged some of these pockets forming disks or protostars. Images of the nebula show pallets of red, pink, blue and grey.

The brighter members of the constellation are hot blue stars except for the top left shoulder star called Betelgeuse appearing bright orange. Opposed the star-forming region of the Orion Nebula, Betelgeuse is at the end of its life and has entered the red giant stage. It has been a highly energetic star in its early life, consuming its fuel in only 10 million years. By comparison, our sun lives at a quieter pace and has a life expectancy of 10 billion years which is presently halfway. Betelgeuse has ballooned out to 950 times that of the sun or if it were at the centre of the solar system would reach out to the orbit of Jupiter. It will explode anytime in the next few hundred years and appear as bright as the full moon.

As we take longer and multiple exposures of the belt stars, the camera reveals the Flame Nebula located east of the left-most belt star named Alnitak located 1,100 light-years away. At about 1,300 light-years away, the Flame is another star-forming region just like M42 but has an obscuring cloud hiding the centre bright stars which are responsible for lighting up the gas and dust thus giving the overall appearance of a flame. This object appears bright beige.

Not too far below Alnitak is the elusive vertical region called the Horsehead Nebula. Long exposure photography is the key to seeing the dark silhouette of this dense dust cloud known as Lynds 1630 thus resembling a horse’s head in front of a hydrogen gas star-forming region. There are no bright areas, just black in front of the deep red hydrogen. This object is difficult to observe visibly and requires very large telescopes and is a challenge to image.

The Quadrantid meteor shower is the first shower of the year. The event is best seen on the night of January 2 into the morning of January 3 with a very sharp peak period that will only last a few hours. According to Pierre Martin, an experienced meteor observer, this narrow peak is predicted to occur around 9:30 a.m. eastern time on the 3rd when the radiant between Bootes, Ursa Major and Hercules is up high. However, the sun will be well up meaning the east coast might have the best chance of seeing the maximum amount of the usual 20 to 30 meteors per hour.

However, based on the modelling by Jenniskens and Peter Brown, the 2021 Quadtantids might be above average. The theoretical filament looks thicker than it did in 2009 which was a great year with the zenithal hourly rates (ZHR) equalling 150. Pierre was able to see the rising rates during the 2009 shower before dawn with 197 meteors seen in just two hours. That shower had the same peak prediction as this year’s event. The downside is the waning gibbous moon will lighten the sky and drown out many meteors. But if you can, try and observe this weekend event as the number of meteors might be high.

I hope you have had the opportunity to observe and photograph the great conjunction of Jupiter and Saturn leading up to the December 21 event. Now separating, the two are sinking lower in the southwest sky and will be lost in the solar glare in the second half of the month but move to the morning sky in February. Venus is now low in the southeast sky and is also moving closer to the solar glare.

The only visible planet seen for part of the night is Mars. At the beginning of the month, it sets at 1:50 a.m. local time and about 1 a.m. by month’s end. Although not as spectacular as last month’s conjunction, Mars and Uranus will come closest together on January 20. They will but 1.6 degrees apart or a little more than three full moons lined up. Mars is still close to magnitude zero while Uranus remains at its usual brightness of magnitude +5.8. It will be to the lower left of Mars and appear as a fuzzy bluish-green star. The first quarter moon will also be in the area, below the pair.

The new moon occurs on January 13 and the Full Wolf Moon lighting up the night on January 28.

Until next month, clear skies everyone.

Gary Boyle

eNews date: 
Friday, January 1, 2021