About how long does sunlight take to reach Earth?

Answer

The Sun is roughly 150 million km away and light covers it at about 300,000 km per second. We always see the Sun as it was a little over 8 minutes ago.

Context

Light travels at 299,792 km per second, and the average Earth-Sun distance is about 149.6 million km, a unit called the astronomical unit. Dividing one by the other gives roughly 499 seconds, which is 8 minutes and 19 seconds. Because Earth's orbit is slightly elliptical, the travel time shifts through the year, from a little over 8 minutes 10 seconds in early January, when Earth is closest, to nearly 8 minutes 27 seconds in early July.

The 8-minute trip is only the last leg. Light made by fusion in the Sun's core is absorbed and re-emitted countless times on its way out through dense plasma, so a typical photon takes thousands of years or more to reach the surface, with published estimates spanning tens of thousands of years, though the number depends on the model. Once it escapes into space it flies unimpeded. Sunlight on your skin was thus produced in the core long before human history, even though it left the Sun's surface minutes ago.

Measuring light's speed has its own history. In 1676 Ole Rømer noticed that eclipses of Jupiter's moon Io occurred later when Earth was farther from Jupiter, and his timings implied light needs about eleven minutes to cross the Sun-Earth distance, a rough early estimate. Modern radar and spacecraft measurements fixed the distances precisely. By the same arithmetic, moonlight arrives in about 1.3 seconds and light from Neptune takes over four hours.