Last Sunday we watched the very popular new show, Cosmos, which is a remake of the famous Carl Sagan series from the 1980’s. In this episode, the astronomer Haley sailed south to chart the stars of the southern hemisphere in the 1600’s. Have you ever wondered what the sky down under looks like? Do they see any of the same constellations we see at night?
Well, actually, they see most of the same constellations we do, but sort of upside down. Here are snapshots from my amateur astronomy software, Starry Night.
The picture above is the sky for March 27th at 10pm for my location in southern Colorado.
The picture above is for Cusco, near Machu Picchu, Peru for March 27th at 10pm.
This picture is for Melbourne, Australia, for March 27th at 10pm. Melbourne is about as far south of the equator and I am north of it.
As you can see, there is an amazing overlap. In Cusco, Peru, which is only 10° below the equator, even the Big dipper is visable above the northern horizon. In Melbourne, which is 37.8° below the equator, only the tail of Draco is visable.
So, what are we missing? The most famous constellation not visable to anyone above 20° latitude is the “Southern Cross” (Cruz). If you can find Centaurus on the Melbourne chart, Cruz is just below the bull’s neck. Although it is a small constellation made up of only a few stars, it is very prominent and is the constellation featured on the Australian and New Zealand flags.
The constellations we can’t see from the northern hemisphere and the constellations they can’t see from the southern hemisphere are called circumpolar constellations. The southern hemisphere has 11 circumpolar constellations, including six first-order magnitude stars, whereas the northern hemisphere only has five circumpolar constellations with no bright stars.
So why are their constellations so numerous and bright? Because the South Pole points toward the center of the Milky Way which is the galaxy where our solar system resides. The brightest constellation is the Southern Cross, and the constellation with the greatest number of visible stars is Centaurus.
Situated near the two brightest stars of the Southern Cross is the most prominent nebula in the Milky Way, the Coalsack Nebula. This nebula is a “dark” nebula so when you look at it, it looks like the dark space between the stars. The Coalsack is part of a series of nebulas strung out across the Milky Way from the Cruz constellation past the Scorpius constellation. The series creates the Australian aboriginal constellation known as the “Emu of the Sky” since the dark spaces look like an Emu flying through the Milky Way.
A brighter nebula, the Eta Carinae Nebula, is home to the most massive star in the galaxy, Eta Carinae, which is one of the most exciting stars because it is unstable and thought to be the next star to die in a supernova. A supernova is when a star explodes. The supernova of 1054 lit up the sky as bright as the sun for almost a year. Over a year later, the Anasazi painted a pictograph under a cliff in Chaco Canyon showing the supernova still as bright as the Moon.
The southern Hemisphere does not have a single star that the others appear to revolve around like our North Star, but it would be an extraordinary sight to see all of those unfamiliar constellations spinning around the southern sky.
— Courtney Miller