This isn’t exactly Ham Radio related, but I thought it fit in this blog…
I just re-watched parts of this video and it really puts the size of even our solar system in perspective. But, I thought of another interesting scenario. Say that right now, the Sun just “goes out” for whatever reason and stops outputting light. Since it takes so long for light to travel across our solar system, we’d be able to see planets blinking out as the last ray of sunlight bounced off and traveled back to Earth. Using wolframalpha.com, I calculated all of the distances and times, and here’s what it would look like:
8.2 minutes after the Sun goes out, we would see it suddenly turn to night. Planets that are currently close to the Sun, such as Mercury, Venus, and Mars would suddenly be visible since we are seeing the light that bounced off them awhile ago. Normally they can only be seen around sunset or sunrise. Venus would be very bright.
It takes about 1.3 seconds for light to travel between Earth and the Moon. If the Moon was Full and visible where you were, the Moon would hang there in space for 2.6 seconds before vanishing as the last light reached it and bounced back to Earth. If the Moon was New, it normally wouldn’t be visible during the day, but since the Sun just went out, and the light from Earth illuminates the dark side (earth-shine), that last earth-shine would travel to the Moon and back, also taking 2.6 seconds. THAT would be eerie… a faintly glowing Moon suddenly appearing in a dark sky and then vanishing 2.6 seconds later. Any other phase would be a combination of the Sun-illuminated surface and earth-shine-illuminated surfaces blinking out one after another all within 2.6 seconds. A Quarter moon would suddenly change into a full-earth-shine-illuminated Moon 1.3 seconds after the Sun vanished, and then would disappear 1.3 seconds after that.
1 minute after the Sun goes out, Mercury would disappear.
10 minutes after the Sun goes out, Venus would disappear.
21 minutes after the Sun goes out, Mars would disappear.
72 minutes after the Sun goes out, Jupiter would disappear. Isn’t that crazy? It would just shine brightly for over an hour from our point of view. Depending on the locations of Jupiter’s moons, they would blink out slightly before or after Jupiter does.
Saturn would finally vanish 159 minutes – over 2.5 hours – after we see the Sun vanish. It takes about .8 seconds for light to travel from one end of Saturn’s rings to the other, so it would appear to “wipe” out from one end to the other, not disappear all at once (through a telescope.)
I didn’t calculate the further planets since they are hard to see anyway.
The times are based on distances from Sun -> Planet -> Earth on 9th Feb, 2015.