[bdamm]

8 minutes is not something we measured.

It is something we computed. Why? Because there is no way to measure the time it takes for light to get from the sun to the earth. You cannot synchronize a message. There is no "hello". There is no beginning. This is not like firing a starting pistol. We cannot ever know what is happening at the sun with less than 8 minutes of lag. It is a fundamental limit. Even sending a highly robust and extremely precise clock into the sun to measure events, then comparing those events to timelines on earth, would not work. You cannot do it in real time, but even after the fact is pretty much not possible due to relativistic effects.

[gridspy]

Good points, but pedantically we can measure such times using a mirror and the round trip of a laser pulse.

This has been done with the moon.

But your points about no 8 minutes of warning stand.

[bdamm]

Even more pedantically, you'd be measuring the round trip time from the earth to a mirror located near the sun and back, but not at the sun. Does there even exist a mirror anywhere in this universe that could survive and float on the "surface" of the sun? Does the sun even have a surface? Is there a laser powerful enough to overcome all of the electromagnetic radiation from the sun such that you could actually discern it's signal? Not pedantically, I stand by my assertion that it cannot be directly measured.

[mewpmewp2]

What in this World can we truly measure anyway?