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Question
I am going on holiday shortly to Lanzarote. Will my planisphere set for Latitude 51.5 degrees North still be able to be used.
Hello William. Thank you for your questions regarding the effective usability of your latitude-fixed planisphere.
The latitudinal distance between the median latitude of your planisphere and that of Lanzarote is 22.5 degrees. That's quite substantial. So much so that your planisphere is probably not going to be able to depict a large chunk of the visible sky towards the South, and will show much to the North that will not actually be visible from Lanzarote. Essentially, there will be somewhere in the neighborhood of 20 extra degrees of sky visible to the South that won't rise above the southern "horizon" on your planisphere, and about 20 degrees of sky to the North that your planisphere will show, but you will not be able to see. Much of your planisphere will still be usable, though. You'll just be limited to a 50-degree-wide swath in the middle of the sky.
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Answers by Expert:
Christopher Watson
Expertise
Can nearly always answer general astronomy questions, and can get much more specific in the areas of stellar evolution, variable stars, astronomical information systems and celestial cartography. Hard astrophysics is not my bag, though.
Experience
Have been involved in observational and computational astronomy for 20 years. Member of and/or contractor to several astronomical organizations. Former officer for one of the largest and most active amateur astronomical associations in the United States. Creator of SkyGX, the most comprehensive and accurate atlas of the sky. Creator of The International Variable Star Index (VSX) at the American Association of Variable Star Observers (AAVSO). Contributing member of The NGC/IC Project. I regularly help professional astronomers with their computational and database needs.
Organizations
American Association of Variable Star Observers (www.aavso.org), The NGC/IC Project (www.ngcic.org), The SkyGX Project (www.skygx.com).
Publications
Several peer-reviewed astronomical journals.
Education/Credentials
None in the field of astromomy. All self-taught.
Awards and Honors
The Special Recognition Award, American Association of Variable Star Observers (AAVSO) [http://www.aavso.org/news/fall06awards.shtml].
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