Question about Jupiter and the Sky Guide

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  • Member since
    December, 2013
Question about Jupiter and the Sky Guide
Posted by msteacher on Saturday, December 28, 2013 1:33 PM

I am new to astronomy and trying to learn all the terms.  Can someone please explain to me the meaning of the phrase, "... planet's 47"-diameter equator."  This is referring to Jupiter on page 2 of the 2014 Sky Guide.  Is this the tilt of Jupiter's equator in seconds?  Thanks.

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  • Member since
    July, 2001
  • From: PA, USA, Earth Moderator
Posted by DaveMitsky on Saturday, December 28, 2013 1:44 PM

No, it's not.  Jupiter will subtend or span 47 arc seconds in apparent size when the planet is at opposition on January 5th.  In other words, the angular diameter of the planet will be 0.013 of a degree. 

http://lcogt.net/spacebook/using-angles-describe-positions-and-apparent-sizes-objects

http://imagine.gsfc.nasa.gov/YBA/HTCas-size/more-ang_size.html

http://astronomy.swin.edu.au/cosmos/A/Angular+Diameter

You may find the astronomical glossaries posted at http://ned.ipac.caltech.edu/level5/Glossary/frames.html and http://www.enchantedlearning.com/subjects/astronomy/glossary/ useful.

Dave Mitsky

Sic itur ad astra!

Chance favors the prepared mind.

A man is a small thing, and the night is very large and full of wonders.

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