some query regarding astronomy

here is the Q

First Question

why at night we do not see any stars near the horizon but if we raise
the viewing angle then we are able to see the stars .like if the
horizon is 180 degrees then we don not see stars till it is around 140
deg. and we are able to see the stars from 140

what might be the reason


Second question


it is about stars and speed of light--

we know that the speed of light is 3 L /sec so it takes arnd 8 mins
for the light from sun to reach earth....i.e light emitted at this
very particular moment from sun will be received after 8 mins at
earth.

well lets increase the distance ..... is a star is suppose 5L light
years away from earth.A supernova occurs at this particular moment ,so
the last light of the star will reach earth after 5L light years
CORRECT?
so what ever we see now at this particular time has actually happened
happened some time back suppose 5L yrs Back in this case.
then how are we able to decide that the star is dead or not.
and if we want to go to the star,we planned a manned space mission for
the star then when we reach there the star is already dead so wont we
be waisting money of the mission!!!!!!.


please reply...
any ideas.....
lets discuss this
bye

.

Relevant Pages

  • Re: More on the controversy about the Schwarzschild radius and black holes.
    ... system in which the Earth is at rest), the stars are all sent hurtling ... the Schwarzschild radius for that mass. ... with the metric around me when the horizon forms. ... singularity, into which the stars disappear upon crossing the horizon. ...
    (sci.physics.relativity)
  • Re: More on the controversy about the Schwarzschild radius and black holes.
    ... system in which the Earth is at rest), the stars are all sent hurtling ... the spherical shell will eventually be concentrated into a single ... singularity, into which the stars disappear upon crossing the horizon. ...
    (sci.physics.relativity)
  • Re: More on the controversy about the Schwarzschild radius and black holes.
    ... Tom Roberts wrote: ... As the stars approach the spatial locus where the horizon will eventually be, an horizon forms at the center and moves outward at the local speed of light, meeting the stars at the locus of the horizon. ...
    (sci.physics.relativity)
  • Re: Sky Chart
    ... In my case, color over horizon is black, constellations line red, ... inside circle night blue. ... Looking for the method how to link stars to define constellations on ... CurrentX = ox ...
    (comp.lang.basic.visual.misc)
  • Re: could have used the stars all along?
    ... >> Say, for GPS navigation, how about using the signals sent from the ... >> after locking on to stars via their relative positions. ... > Celestial navigation is about finding out where the vertical at your ... > And there's still the problem of identifying the vertical or horizon. ...
    (sci.geo.satellite-nav)