Star Spy: Star perspective

Last updated 14:40 17/12/2012

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Is it a great hunter, a cooking utensil, or perhaps a farming implement?

Some seem to think it might be ‘the plough’, which actually is in the far north and not quite visible from here in New Zealand.

As for the hunter and the cooking pot, it depends entirely on how you look at it, in particular, on where you stand when you are looking at it.

For example, you can stick a picture of a tree (or anything that has a definite top and bottom) on the ceiling in the middle of a room and walk to the wall indicated by the top of the tree. Then turn around and look up at the ceiling and the picture will appear right side up. 

Now walk to the opposite wall and do the same. The picture will now appear upside down. Not a mystery, no magic twisting going on.

It is the same situation when looking up at the night sky. North and south are opposite sides of the very large area from which we all can look up and observe the sky. 

As it happens, Orion is located directly over the equator of Earth, kind of like the ceiling in the middle of the room. So those in the northern hemisphere have to look south to see him. We in the south must look north. 

There is no ‘correct’ view. It simply depends on the direction you are looking. Each view is upside down from the other.  

The man depicted in the sky for northern hemisphere dwellers has been known since antiquity, variously as a God, a pharaoh, a shepherd, etc, and as the giant hunter of Greek mythology, Orion. 

However, in our southern hemisphere upside down view of him, we don’t look up and see a man’s belt with a sword hanging down. We see a cooking pot with a handle sticking up, and fair enough.

The man is upside down for us. The pot is upside down for Europeans.     

A guest from Australia on one of my stargazing tours referred to The Saucepan as The Shopping Trolley. The next time you are out on a clear night, check The Saucepan and see what you think.


Back in the image of Jupiter and its four biggest and brightest moons, Consider Europa. 

It is a little smaller than Io, orbits farther from its planet, and could hardly be a more different place. 

Instead of active volcanoes, Europa is covered with a layer of water about 100km deep. 

The smooth surface is a crust of ice, but it is considered likely that a warmer, liquid ocean exists below.  

Europa has few impact craters, compared to the outer two Galilean moons. This indicates a young surface, one that renews itself, perhaps with some regularity, as from a liquid ocean that occasionally breaks through its icy crust to spread on the surface, where it fills in the craters and freezes to form a new, smooth top layer. 

It is widely thought possible that living organisms may have formed in this ocean, perhaps similar to microbial and other life forms we are finding in deep ocean trenches on Earth, and beneath our polar ice; life forms that may still populate Europa’s possible ocean. 

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This life-forming prospect of Europa featured prominently in the movie 2010, sequel to the science fiction classic 2001. 

The moon’s bright surface is criss-crossed with dark lines, apparent cracks in the relatively thin ice – thin relative to the layer of ice covering each of the outer two Galilean moons.

It has been suggested that, while Curiosity searches for evidence of life that may once have existed on ancient Mars, we should also be exploring Europa, confirming the existence of its ocean, and searching for the organisms that may thrive there today.

- Stuff

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