proportion of sky visible from earth observer?

[botanic]

A heated debate has ensued between yours truly and a digsmate who's dad is an imenent astrophysicist.<br />Question: <br />What proportion of the sky is visible from a point on the earth - say with clear horizons (e.g. out to sea).<br />Now I would have said basically half the sky as if one draws a tangent from the top of the earth and extends it in all directions, and does the same on the other half opposite pole of the earth, the entire universe should be visble (minus a band the width of earth extended in all directions). <br /><br />Anonymous digsmate says only a small proportion of sky visible (like an eighth), claiming the view of a large proportion of the sky is blocked out by the earths curvature (much more than half). <br /><br />Who is spatially challenged here? Me or me?

 

[harmonicaman]

I'd tend to agree with you Bot; I think we can observe about 1/2 of the Celestial Dome under ideal conditions.

 

[newtonian]

botanic - basically you are correct.<br /><br />Note that a large portion of universe is blocked by the disc and core bulge of Milky Way - perhaps there was a misunderstanding?<br /><br />Earth's curvature is down, not up - it would tend to allow more sky in view, not less.<br /><br />However, earth's curvature in space, in orbit around the Milky Way, does indeed obscure a large portion of sky - not 7/8ths - perhaps 1/8th?<br /><br />There is one other possible way your (digsmate??) could be correct.<br /><br />You specified out to sea.<br /><br />Perhaps he (she) was in the hold of a ship with a window allowing only 1/8th of the sky to be viewed!