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Q & A: Year-long observations of constellations

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Most recent answer: 05/02/2009
Q:
Hi i was wondering if you could please tell me why is it that if we rotate around the sun (12hrs facing/12 hrs facing away) we seem to always be able to see certain star formations (southern cross, etc)? I mean at 1 half of the year (say Jan 1) we are technically facing out (during night time) to one side of our universe & then at the other (June 1) we would be facing the opposite side... do the stars orbit as well & if so at what level? Thank you
- Phill (age 22)
Perth, Western Australia
A:
It's a matter of the latitude where you live and the celestial latitude of the particular constellation.  You Australians live in a southern latitude, about 32o South for Perth,
I live in Urbana, Illinois about 42North.   You can see the Southern Cross year-round because it's celestial latitude is about 60o South but you will never see the Big Dipper or the North Star. I can see the Big Dipper year-round but never the Southern Cross.  Stars and constellations closer to the celestial equator go in and out of visibility annually, in just the way you pictured..
See    for some hints.

LeeH

(published on 05/02/2009)

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