Today I would like to look at some more science type things and also a bit of backup information regarding a post I made earlier in the year about the expansion of the universe and it’s inevitable eventual collapse.
Now then the sun, or big bright thing in the sky is on average 150.000.000 KM away from the earth, I say on average because the earth’s orbit is an elliptical one and so the distance will vary. This means that by looking towards the sun we are in effect looking directly into the past as it takes sunlight 8 minutes to reach earth. So if the sun suddenly went out we would be none the wiser for 8 minutes.
Another fact about the sun would be the fact that you can actually see the sun before sunrise and after sunset, you see Sunrise is defined as the moment that the Sun first appears over the horizon. So, by definition, you can't see the Sun before it appears. But you're right that we can see the Sun even when it is *geometrically* just below the horizon, at both sunrise and sunset. This is because of the refraction of the light from the Sun by the Earth's atmosphere--the Earth's atmosphere bends the path of the light so that we see the Sun in a position slightly different from where it really is. The magnitude of this effect varies with latitude, but it's strongest at the equator, where the Sun rises 2 minutes earlier than it would if the Earth had no atmosphere, and sets 2 minutes after it would if the Earth had no atmosphere. However, that light has still taken about 8 minues to get here so think about that and make your head hurt a bit.
Looking further out into space the light from many distant stars that we are now viewing could well have been travelling for billions of years, longer than the age of the Earth itself.
Recent images gathered from very powerful telescopes has captured imagery of some of these distant stars and galaxies and they are all red in hue.
To explain what these far off images being red means is a basic understanding of light and waves. As light is stretched it’s wavelength becomes longer and hence its colour moves towards the red end of the colour spectrum. But the only way light would do this is if it is being stretched and therefore for this light at the far end of our viewable universe to be stretched the universe must then be actually expanding.
If the universe were actually collapsing then again like the sun switching itself off we would be none the wiser for quite some considerable time as the light from a collapsing universe would still take many light years to reach us and to be honest the chance of you or I still been around are very very small.
And so to parting words for the day,