The Sun is completely blocked in a solar eclipse because the Moon passes between Earth and the Sun. Even though the Moon is much smaller than the Sun, because it is just the right distance away from Earth, the Moon can fully blocks the Sun’s light from Earth’s perspective.
Alpha motor neurons (also called lower motor neurons) innervate skeletal muscle and cause the muscle contractions that generate movement. Motor neurons release the neurotransmitter acetylcholine at a synapse called the neuromuscular junction.