Roemer was the first to measure the speed of light.
You should try to check on sciencebuddies.org
Galileo attempted to measure the speed of light using lanterns positioned at known distances and observing the time it took for light to travel between them. He would uncover the lanterns simultaneously and use a telescope to try and detect any delay in the light reaching his eyes. However, his methods were not sensitive enough to accurately measure the speed of light.
Light years
No, a megaphone is a device used to amplify sound, particularly human speech. It does not measure light or speed.
by getting boners.
Light is faster because speed does not move. Speed is a measure of the rate of movement but, in itself, it does not move - at all!
Roughly speaking, light moves about a million times faster than sound in air.
Light travels at about 186,000 miles per second
The speed of light isn't a distance so it has no length it is a measure of speed, which is roughly 186000 miles per second.
The speed of sound in air is about 343 m/s, and the speed of light in a vacuum is about 299,792 km/s. When added together, the speed of sound and the speed of light do not directly add up because sound requires a medium to travel through, while light can travel in a vacuum.
It doesn't work that way. The light-year is not used to measure the speed of light. It works the other way round: First, the speed of light is determined through other methods, then the distance called a light-year is calculated based on that measurements.
The first successful attempt to measure the speed of light was in 1676 by Danish astronomer Ole Rømer. He estimated the speed of light by observing the eclipses of Jupiter's moon Io.