Space exploration
Almost everything known about space arrives as electromagnetic radiation, which travels fast but not instantly across huge distances.
A worked example
Light and radio waves travel about 300 000 km each second, so a signal from the Moon at 384 000 km takes 384 000 / 300 000 = 1.3 seconds.
The mistake people actually make
Divide distance by speed to get the delay, and remember that figure is one way. A question and its reply take twice as long. Optical and radio telescopes collect different information, not the same picture at different quality.