Thousand-year-old Light

But we have a much more striking illustration and correspondence in the

case of the transmission of light from the distant stars, which we will

do well to carefully consider. Light travels at the rate of 186,000

miles per second. A "light-year," as known to astronomers, means the

distance traversed by a light wave (at the stated rate of travel) during

the period of one of our earth years. Some of the distant stars are

stimated to be fully one thousand light-years distant from us; or, in

other words, the light we now perceive as coming from them really is the

light that left them one thousand years ago. If one of these stars were

to be destroyed, observers on this earth would not become aware of it

for a thousand years. The star whose light we may now perceive may

actually have been destroyed nearly one thousand years ago. Other stars

are only one hundred light-years removed from us in space; others only a

few years; others only a few hours. But the principle is just the same

in all cases, namely, that we see the stars not as they are at the

present moment, but as they were when the light left them, perhaps many

years ago. Thus, as you see, we may actually perceive events long after

their happening.