1/ The speed of light is generally rounded down to 186,000 miles per second. In exact terms it is 299,792,458 m/s (meters per second - that is equal to 186, 287.49 miles per second).
2/ It takes 8 minutes 17 seconds for light to travel from the Sun's surface to the Earth.
When Mars is closest to the Earth, it takes light three minutes to travel between the two planets. If you asked a question to an astronaut on Mars, you'd have to wait at least six minutes for an answer, and Mars is usually a lot farther away than that. At its greatest distance, you'd have to wait 42 minutes, or even longer if the astronaut is watching Gilmore Girls. In the future, there will be no such thing as sending an "instant message" to your friends on the Mars base. There also won't be any day trading or free pizza delivery.
