alanchua wrote:Hi Gary. Thanks for the advice. The youtube I am referring to is
http://www.youtube.com/watch?feature=pl ... bz3QnAbzFM
The guy was mentioning about the blue cross when he demonstrate and he say that this is actually directly above our head.
Reason why I am asking is if I am using the manual way to locate stars, I may not know where a particular star is on the real sky with reference to the planisphere.
Hi Alan,
If I understand him correctly, it just means zenith. The "problem" with portable planisphere is the need to squeeze all the constellations into that small display area which results in some constellations getting distorted, which may add further confusion to newcomers trying to recognise them.
Planisphere is one portable manual way to learn about the constellations and stars in the sky on a field. But not the only way and may not be the best since we all have our own preference when it comes to learning a new subject matter. So don't restrict yourself to using only a planisphere.
Suggestion: Go to
http://www.skymaps.com and print out the latest pdf monthly chart (Sep 2013 Equatorial Edition for use in Singapore). Read the instructions printed on the 2-page pdf. The + in the middle of that map is directly above your head (zenith).
Since there is a bigger area to display the constellations, there is less distortion. Print A3 if you want to see better and bring it out to observe. Use a red torchlight to illuminated the printed sky map.
Now, the method to relate the size of the constellation in the printed map vs the real sky:
- The bigger the black dots in the map, the brighter the stars.
- Try to find and identify the constellations with more bigger black dots on average - they will be easier to identify in the sky. E.g. Scorpius, Saggitarius.
- Now map the brighter stars in the sky map with the visible stars in the constellation in the sky. You will then see the actual size of the constellations in the sky if its clear enough.
- You can also try to correlate the other brighter dots in the map in the sky and use them as navigational signpost - e.g the star Vega.
Be patient, if the sky is not clear enough, don't stress yourself trying to find them with a sky map or planisphere. Just continue to wait for a clear enough night. It will come sooner or later.
Also learn how to use your hand and fingers to measure angular size in the sky. This will help you scale correctly when you to estimate how big or wide a constellation should be in the real sky:
https://dept.astro.lsa.umich.edu/ugacti ... index.html
Ironically, once you figure out how to use the printed skymap, you may increase your understanding of how to use the planisphere. Then from that point onwards, you can just use the planishpere since it looks cooler, waterproofed, and sturdier to hold on to. And you don't have to carry too many skymap papers with you while in the field.
Again, the best way is just to approach a telescope volunteer during public stargazing sessions and learn from them directly and efficiently under a real night sky.
P.S. You should see how the constellations are squeezed into faceplate of my astro planisphere wrist watch! Then you even more stress!
"The universe is composed mainly of hydrogen and ignorance." 