Wonders of the Southern Hemisphere night skies: part 1

Visitors to the 2019 eclipse will have plenty of new constellations, bright stars and stunning objects to find

Need persuading to go all the way to Chile, Argentina or the South Pacific to see the Total Solar Eclipse on 2 July, 2019?

There’s no better place to stargaze than Chile, northwest Argentina or the South Pacific.

For visitors to the Southern Hemisphere, know that you will be greeted by a whole new set of constellations, bright stars and stunning objects only viewable from these latitudes; there’s a reason why astronomers have chosen Chile to build the very biggest and best ground-based telescopes.

Judged purely on targets, the Southern Hemisphere the best place to be for stargazers. While the north pole faces outwards to the Universe beyond, the south pole points to the galactic center of the Milky Way. That has obvious consequences for stargazing; there are billions of stars, and more bright stars, more constellations containing more objects in the southern skies. For stargazers, it’s hard to resist. Here’s a hit list of the top sights in the Southern Hemisphere to search for in June and July, adapted from my book A Stargazing Program For Beginners: A Pocket Field Guide published by Springer.

You get your own view of what the world’s biggest telescopes in Chile are looking at every night by aiming your binoculars or a telescope at these sights:

1 – Alpha Centauri

Alpha Centauri is the third brightest star in the sky. Also known as Rigil Kent, it’s 4.3 light-years from Earth. It’s actually a double star itself, made from two Sun-like stars, though together with tiny Proxima Centauri (the closest star to our Sun), Alpha Centauri is a triple star system.

To watch Alpha Centauri and ponder whether humans might one day visit this star system is a special treat when traveling to the southern hemisphere. However, it would take tens of thousands of years to reach Alpha Centauri or Proxima Centauri on current rocket technology. It’s probably best we wait for a technological breakthrough before contemplating a trip, but navigating home would be easy; in Alpha Centauri’s night sky our Sun would appear as a bright star, close to the ‘M’ or ‘W’-shaped constellation of Cassiopeia.

2 – Southern Pointers

Alpha Centauri has a close visual neighbor that’s bright though much, much further away. Beta Centauri, or Hadar, the less bright of the two, is 390 light years distant and 10,000 times brighter than our Sun. It’s actually two stars orbiting each other. Alpha Centauri and Beta Centauri – both in the constellation of Centaurus – are together called the Southern Pointers because they point straight to Crux, the Southern Cross. If you don’t use the Southern Pointers to find it, you may fall into the common trap of identifying what’s known as the False Cross, a bigger asterism within the constellation of Carina to the east.

3 – The Southern Cross (Crux)

The southern hemisphere doesn’t have a pole star, but when it comes to both navigating and stargazing, there’s only one constellation in town – the Southern Cross. It is the brightest and the most famous of all southern sky shapes, and can be found on the flag of Brazil, and even more prominently on the flags of Australia and New Zealand. From July to September the Pointer Stars will be above Crux, which will be lower in the sky. Locate Alpha Centauri and Beta Centauri. Starting at Alpha Centauri, go three times the distance between those two stars and you’ll arrive at the star Gacrux at the top of the Southern Cross.

You may initially be disappointed by the tiny size of Crux, but around it are some of the night sky’s very finest sights. Sweep some binoculars across this region of the Milky Way and you’re confronted with numerous stunning star clusters.

4 – Jewel Box cluster (NGC 4755)

Fans of the Perseus Double Cluster over in the Perseus Arm of the Milky Way will find a sister sight in the southern hemisphere of a similar age and distance – and you don’t have to move far from Crux. A mix of over 100 sparkling red and blue stars, the Jewel Box cluster is well named, and great to look at through binoculars or a small telescope.

Around 6,400 light-years away and also known as the Kappis Crucis Cluster and NGC 4755, it’s easily found. Visualize a line from Gacrux at the top of the cross through Becrux on the eastern side of the cross, and keep going for a just quarter of the distance of that line. You’ll hopefully see what may look like a single star with your naked eye. Train your binoculars on it and you should see about four stars. In a telescope it’s revealed as a bright open cluster of sparkling giant blue stars with an orange supergiant in the center. The contrast is stunning. The Jewel Box Cluster is reckoned to be a mere seven million years old.

5 – Coalsack Nebula

Don’t rush this one. Range slightly below the Jewel Box Cluster and you’ll come to a dark band over the Milky Way. An interstellar dust cloud that prevents the light from stars within the Milky Way from reaching us, the Coalsack is just 600 light years away. Put your binoculars over it and you won’t see much; the stars that are visible are actually in front of it. This dark nebula constitutes the remains of exploded stars, and will go on to become the birthplace of new stars. If you’re in a dark sky site and can see an otherwise bright Milky Way, the Coalsack is pretty obvious if you look for long enough.

Pic credit: Pixabay

Part 2 to follow on 5 January 2018.