Winter SHemis Aust 9pmFEA

The Stars Go Backwards In Australia

The northern sky viewed from southern Australia (about latitude 32 degrees south) in mid-January. Not only are the familiar constellations "upside down", but the turning of the Earth causes the sky objects in the northern sky to travel from right to left instead of left to right. The moon's position is shown for tonight. Stellarium
The northern sky viewed from southern Australia (about latitude 32 degrees south) in mid-January. Not only are the familiar constellations “upside down”, but the turning of the Earth causes the sky objects in the northern sky to travel from right to left instead of left to right. The moon’s position is shown for tonight. Stellarium

Well, at least for northerners they do. With winter thick upon us and temperatures well below zero the past few days, my mind turned to summer. Then to Australia, where summer has been underway for nearly a month.  Sydney’s temp should hit 85 degrees tomorrow.

Anyone who’s ever traveled to the southern hemisphere knows how unfamiliar the night sky appears. There’s a whole new set of constellations down there. Ones that have been hiding beneath a northerner’s southern horizon for years. To see them, we must jump a plane and travel the curve of Earth for hours to coax them into view.

Looking north from mid-northern latitudes toward Orion and the winter constellations mid-evening in January. Stellarium
Looking south from mid-northern latitudes toward Orion and the winter constellations mid-evening in January. The moon is shown for tonight. Stellarium

Learning the southern sky constellations of Pavo the Peacock, Octans the Octant or Vela the Sails requires a good map. You can create your own with Stellarium (download at stellarium.org) or sign-up / login at Heavens-Above, select “Change your observing location” under Configuration, scroll down and click “add new”. Then select the city of your choice, return to the homepage and click on Sky Chart under Astronomy for a map showing the sky anytime from your new southern city. Another easy option is the interactive map at Sky Map Online.

While you’re fathoming those new stars, don’t forget to turn around and look at the old, familiar crew. For a vivid sense of having traveled far, there’s nothing like facing the northern sky (from whence you came) and seeing all the star patterns completely upside down. Not only that, but the stars, moon and sun all travel “backwards” compared to what we see in the north. Instead of moving from left to right across the sky during the night/day as you face south, they travel from right to left as you face north. Totally nuts!

Likewise the lunar phases. Here in the north, the moon fills out from right to left as its phase waxes from crescent to full. From the southern hemisphere, the direction is reversed. The waxing crescent moon looks like a waning crescent to northern eyes.

Facing south in mid-January from Sydney, we look toward the faint southern pole star, Sigma Octantis in Octans the Octant. At lower left you can see the Southern Cross, also called Crux. Stellarium
Facing south in mid-January from Sydney, we look toward the faint southern pole star, Sigma Octantis in Octans the Octant. At lower left you can see the Southern Cross, also called Crux. Stellarium

It sounds bizarre because we see all those things happening in our southern sky, while for down underers it all takes place in the north. The simple act of turning around reverses the normal directions. If we face south in the southern hemisphere we see the faint south pole star, Sigma Octantis in Octans, and the south polar constellations of Chameleon, Tucana the Toucan and Pavo the Peacock. They pivot around the pole star, albeit a much fainter one, just like the northern circumpolar constellations circle about our north star, Polaris in the Little Dipper.

If only to have our celestial perspective shaken up and altered, I’d advise a trip below the equator for northerners and above it for those down under. And just think. For those in the deep south, Orion’s a summertime constellation, one you’d see while swatting flies on a balmy night. I wouldn’t mind a piece of that right now.

As for that old saw about water going the opposite way down a bathtub drain in the southern hemisphere, the answer is yes and no. Mostly no, but I’ll let Scientific American present the case.

6 Responses

  1. Hi Bob,

    I was lucky enough to visit Australia in January (many years ago now) and, although I got some great views of the “upside down” constellations, the first thing I noticed was how disoriented I was just walking around in the daytime… purely because the Sun was in the North. I remember heading into North Sydney all the while convinced I was heading South.

    It takes some getting used to and, you’re right, it’s totally nuts to see the Sun rise in what we Northern Hemisphere dwellers would think of as the West and set in the East.

    1. astrobob

      Hi Paul,
      Thanks for sharing that experience. The furthest south I’ve been was about -16 degrees in southern Peru. There the sun is always pretty high up, but the thing that really caught my eye besides the upside-down constellations was seeing the moon go through phases seemingly in the reverse order from those at home.

  2. Hi Bob,
    Great descriptive post, as always. Note the typos/contradictory directions in the first two image descriptions (typo in white-text overlay in the first, and in caption in the 2nd). At least I think it’s a typo; hard to imagine that first image could even be real!!

    1. astrobob

      Hi Jim,
      Arrrgh! Thank you so much for catching those. Really appreciate it. Now corrected. Clearly, I got turned around in my head!

      1. Excellent! Now I can add this one to my Evernote “Solar Dance” collection, the raw material for some sort of “three dimensional sense of place in space” thing I may put together someday. Thanks to Guy O for opening that window, years ago….gonna miss his annual calendar, but I can well imagine what drudgery that had gotten to be for him; glad he’s actively blogging. Between the two of you, I’m able to stay pretty well oriented here on the edge of the earth, at the bottom of the sky.

        1. astrobob

          Jim,
          I loved Guy’s calendar. The big format and the great 3D visuals. I didn’t know he was blogging – I will definitely look him up.

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