What are sky maps? How are they made?

1 Answer
Jul 13, 2016

Mapping the sky every night, over a year, the narrow peripheral changes are observable. Overall, joining of these maps, with due care to avoid marginal repetitions,the sky map is obtained.

Explanation:

Sky maps usually show stars in the space around, with other space

bodies that reveal their presence, by reflecting light from their

parent stars. In brief, they reveal which is which in the star world.

Making of sky map:

By conical angular rotation of the viewing device, the map for the

night sky could be made by the cut-paste method.

The pre-telescope mapping divided the #WHOLE# sky around into

12 zodiacs. Each covered 2-D #30^o# Earth's orbit-revolution-angle

(3-D #60^o# conical angle). Even now, this is handy to astrologers.

Then 12 became 13, and now, the division designates 88

constellations..

Broader division is into

North Circumpolar skies,

Eastern skies

Western skies

South Circumpolar skies.

For this sky atlas see

pp 309-338, Deep Sky Objects (2005), David H. Levy