Tonights Target for Universe Watch – Alpha Centauri


Alpha Centauri  has been added to Universe Watch in the menu on the right hand side of the screen. You can find Alpha Centauri in the sky by looking south-south-west and it is fairly low in the sky. Have a look at the Universe Watch section to find out how to find it.


Alpha Centauri

Alpha Centauri (Click to Enlarge)

When looking at the objects in the sky above you, you need to keep in mind that what you see up there is not a live telecast of what is happening at that very minute. Think of it as a delayed telecast and you are seeing the show some time after the live event.


This is because light travels at a speed of 1,079 million kilometres an hour. So when you look at the Sun, never look directly at the sun without a proper solar filter, you are actually looking at what the Sun looked like 8 minutes ago. This is because of the Sun’s distance from the Earth.

Yesterday when members of the Northern Sydney Astronomical Society watched Jupiter’s moon of Ganymede do a shadow transit across Jupiter, we did not see this event live either. At the current distance of Jupiter, we would have seen the shadow transit 42 minutes after it actually happened.

So when you look at Alpha Centauri tonight which is 41,532,606,774,629  kilometres away from us, you are actually looking at Alpha Centauri as it looked 4.39 years ago.

This gives a little bit of mystery to the whole star gazing thing as we are looking at events which occurred in the past and a lot can change in 4 years.

~ by sydneystargazers on October 17, 2009.

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