How long does light from the Sun take to reach Earth?

About eight minutes and twenty seconds. Every time you look at the Sun you are seeing it as it was before you left the house. If it were somehow switched off, we would carry on in daylight for eight minutes, and the Earth would continue in its orbit for the same eight minutes, because gravity travels at the same speed.

That energy took very much longer to get out of the Sun than to cross to us. It is made in the core, and then spends somewhere between ten thousand and a hundred and seventy thousand years being absorbed and re-emitted by the dense plasma above it, staggering outward in a random walk. Sunlight is old before it is light.

The delay makes distance measurable in time, which is how astronomy mostly works. The Moon is a little over a second away. Mars is between four and twenty-four minutes, which is why nobody can drive a rover with a joystick. The nearest star after our own is four years off, so we necessarily see everything in the universe as it used to be.