Sand and Stars

Magnificent Orion

Orion in Bode’s 1801 Uranographia

Orion, the hunter, is the most magnificent constellation in our skies. It contains some of the sky’s most spectacular sights within reach of binoculars, among them one of the greatest celestial treasures: M42, the great Orion Nebula.  

In the image Orion is raising his club and shield against the charging Taurus as illustrated in the Uranographia of Johann Bode (1801). However, this is how he appears when you are in the northern hemisphere. Here in the southern hemisphere he appears upside down as if his bright and beautiful stars are doing a spectacular cartwheel across our sky.

For that reason the star chart is oriented correctly for the southern hemisphere. You can use Orion’s brilliantly bright stars to navigate to his treasures, which makes them easy to find in binoculars. (And don’t forget to be comfortable to minimise shaking and tired arms. There is a lot to see in Orion! Either lie on your back with your binoculars balanced steadily on your face, or lean back in a chair with your elbows on the arms, or brace your binoculars against a wall or tree.)

Orion as he appears in the southern hemisphere

Orion cartwheeling across our southern skies

Orion’s Stars 

With one exception, all of the main stars outlining Orion’s body and belt are bright young blue giants or supergiants. The exception is Betelgeuse which is a red supergiant and one of the largest stars known. You can clearly see the difference in colour between red Betelgeuse and all the other blue-white stars.

How far away are these stars? Observed from Earth, the night sky appears two-dimensional. But we all know that the stars are scattered through three-dimensional space. The image below shows you how far in light-years Orion’s brightest stars are from Earth. (One light-year is the distance light travels in a single year, about 10 trillion kilometers.)

Distance to Orion’s bright stars

To give you some perspective of the size of these stars – Rigel (Alpha Orionis) is a massive blue supergiant and the brightest star in Orion; it is 777 light years away and 51,000 times as bright as the Sun. Bellatrix (Gamma Orionis) is fainter than Rigel but it is a lot closer at 243 light years, and only (!) 6,000 times as luminous as the Sun. (Rigel’s name is derived from the ancient Arabic for “the left leg of the giant”. And Bellatrix translates from the Latin for “female warrior”.) 

Famous Betelgeuse (Alpha Orionis)

This photo, taken by the ALMA telescope in Chile, shows Betelgeuse’s irregular blob shape and was the first photo ever taken of the surface of a star. Image credit ALMA/ESO

Betelgeuse is the most famous star in Orion (if not the entire sky). It is a massive red supergiant and unlike our smooth, spherical Sun, Betelgeuse is a churning hot blob of a star. And it’s one of the biggest stars we know: if it replaced the Sun at the center of our solar system, it would extend past the orbit of Jupiter. (The name Betelgeuse is derived from the ancient Arabic for “shoulder of the giant”.) 

Betelgeuse is nearing the end of its life and it will die in spectacular fashion by blowing itself to smithereens in a supernova explosion. Of course, Betelgeuse may have gone supernova yesterday but we won’t know for another 429 years, when its light eventually reaches us. 

Orion’s Shield Stars

Tracing out the stars that form Orion’s shield and club allow you to appreciate how enormous Orion is and how much of our sky he occupies (594 square degrees, to be exact). His shield is a striking crooked arc of stars numbered Pi-1 through Pi-6 Orionis (though they have nothing physically to do with each other). In the middle lies the brightest of the shield’s stars named Tabit, an Arabic word meaning “the Endurer”. Why the ancients named this faint star is a mystery.

Orion’s Club Stars

Proximity in the sky, the mythological story, and their similar apparent brightness can fool us into thinking that this pair of stars must be similar. But these two stars are very different to each other. Chi-2 is an aging supergiant and lies 4,900 light years away – and it shines with a spectacular luminosity of nearly half a million Suns. Chi- 1 is not only one of the closer stars to the Earth (just 28 light years away), but it also a near-replica of our Sun (which is a yellow dwarf star).

Meissa (Lambda Orionis)

DSS image

Orion’s head comprises three naked eye stars that form a small but attractive isosceles triangle. Meissa is the brightest of the three. Meissa is actually the lucida (brightest star) of an open star cluster known as the Lambda Orionis Cluster (also known as Collinder 69). The cluster is young, in astronomical terms, and probably formed around five million years ago. It still has remnants of its nebulous star birth cloud softly enveloping the stars, but alas, not visible in binoculars.

This is a lovely little cluster in binoculars. Depending on your binoculars and the darkness of your skies, you ought to be able to count anywhere up to 15 or so stars, albeit many are pretty small and faint.

Meissa’s name is derived from the ancient Arabic meaning “the shining one”. It was originally used for Gamma Geminorum, but was mistakenly applied to Lambda Orionis and the name stuck.

Orion’s Belt

Image credit Davide De Martin/ESA/ESO/NASA
Naked eye, Orion’s Belt is a magnificent cosmic wonder. with its three exceptionally hot and massive blue supergiants evenly spaced in a line at a jaunty angle. (They are also sometimes known as the Three Sisters.) Looking at the three belt stars through a pair of binoculars is overwhelming because there is no indication naked eye of what you will see – the three very bright bluish-white stars surrounded by loads of fainter stars that fill up the field of view. This is the Collinder 70 cluster which is made up of the three belt-stars and around 80 or so stars surrounding them.
DSS image

This is what you can expect to see when you look at Orion’s three belt stars through binoculars.

It’s a tremendous view because there is a large range of brightness, from the very bright belt-stars to very faint stars and they are scattered everywhere. Like other rich clusters, you will see some lovely patterns in the cluster – the most prominent one being the way the stars wind themselves in a gorgeous long starry chain around the three brilliant supergiants.

The famous dark Horsehead Nebula lives in this part of the sky. You can see it in the colour image – it lies just below Alnitak. Unfortunately, you need a big telescope to see it.

Orion’s Sword

DSS image annotated

Dangling from Orion’s Belt is the Hunter’s mighty three-star sword. But as you can see from the annotated image… “three-star sword” is only a traditional name, as even a pair of binoculars reveal a glorious array of stars, clusters and an incredible star birth cloud.


M42, the great Orion Nebula

DSS image

Naked eye, the middle “star” in Orion’s Sword looks decidedly fuzzy, like a faraway streetlight seen on a foggy night. It’s not a fuzzy star at all… it is one of the sky’s greatest celestial treasures: the nearest and most active stellar nursery in the Milky Way Galaxy, where baby stars are being born from the vast cloud of gas and dust. Most nebulae are difficult if not impossible to see with the unaided eye or even binoculars. But the Orion Nebula is in a class all of its own. It’s bright enough to be visible even in light-polluted conditions, and under a dark sky it’s truly stunning.

The nebula is about 24 light-years across and is about 2 million years old according to NASA Jet Propulsion Laboratory. It is home to some of our galaxy’s youngest, and hottest stars. Indeed, the enormous cloud of dust and gas glows because of the ultraviolet radiation streaming from the central Trapezium star cluster (Theta Orionis). These stars are a mere 300,000 years old, which in human terms is like being born a few seconds ago. You can see two of these superb stars glittering in the misty nebula. Take your time with the Orion Nebula — the longer you look, the more you’ll see. You can’t pick up tiny M43, although of course if you have M42 in your binoculars you also have unseen M43 in the same field of view.


Na’ir al Saif (Iota Orionis) and NGC 1980

DSS image

Na’ir al Saif is the brightest star in Orion’s sword. Its name is Arabic for “the Bright One in the Sword.” The name “Saif” (sword) was erroneously transferred to the lower left star of Orion’s seven-star figure (Kappa Orionis), and it stuck. 

Although we can only see one star, it is actually a complex quadruple star. It is a member of  — the southernmost star in Orion’s Sword. It is the lucida (brightest member) of the small open star cluster called NGC 1980. Around 4.7 million years old, the cluster is still immersed in veils of nebulosity visible through telescopes.

In binoculars you will see that NGC 1980 is a sparse cluster… but very beautiful with the smaller sparkling stars showing a nice range of brightness. 

NGC 1977

DSS image

The faintest of the three naked-eye stars in Orion’s Sword is revealed to be two lovely stars in binoculars – 42 Orionis and 45 Orionis. They are surrounded by  several swathes of bright and dark nebulosity, and under dark and steady skies (and with eyes well dark-adapted), some observers have seen faint and ghostly tendrils of this nebulosity.

Copyright © Susan Young 2023