The actual annular portion, in which the sun appears as a thin ring, will be about four minutes long, Newmark said.

CNN: Upcoming solar eclipse to project 'ring of fire'

"For the May eclipse, the moon will be at the furthest distance from Earth that it ever achieves -- meaning that it will block the smallest possible portion of the sun, and leave the largest possible bright ring around the outside, " the agency said on its website.

CNN: Upcoming solar eclipse to project 'ring of fire'

During his 32nd solar eclipse observation, the Harvard-trained astronomer is to study the elusive coronal ring, the outer atmosphere of the sun, which can only be seen when the moon blots out the solar disk.

CNN: Africa awaits total eclipse of the sun