What is the name of the cosmic coincidence, when the sun, moon, and earth are perfectly aligned, can scientists get a better look at the sun?

When the Sun is eclipsed by the Moon this Sunday, for many observers across much of the world it will be temporarily replaced by a beautiful ring of fire - a brilliant annulus of stellar plasma just peeking out around the dark lunar disk. This doesn't always happen, partial solar eclipses merely trim away a chunk of the solar disk, and true total eclipses perfectly blank out the visible surface of the Sun. It's all a matter of alignment between Sun-Moon-Earth and our mutual orbital gymnastics.

they deliver oxygen to the blood