Comstock Images/Comstock/Getty Images
When the Moon aligns perfectly between the Sun and Earth, it can cover the Sun’s bright disk entirely. The result is a total solar eclipse, a rare celestial event that allows us to observe the Sun’s outer atmosphere, the corona, and a series of stunning optical phenomena.
During totality, a radiant crown of plasma — the corona — illuminates the space around the Moon. The corona extends millions of kilometers into space and, when viewed through a telescope, reveals a faint, pearly halo of white and pale blue light. Occasionally, bright red loops appear in the corona, produced by hydrogen gas flowing along the Sun’s magnetic field lines associated with sunspots.
At first contact, the Moon’s leading edge begins to touch the Sun’s disk, turning the once‑full Sun into a thin crescent. Second contact marks the moment the Moon fully covers the Sun; the Sun’s light is now visible only as a slender rim along the Moon’s edge, reflecting the rugged topography of the lunar surface.
Just after second contact, bright beads of sunlight—known as Baily’s beads—appear along the Moon’s western limb. These beads form when the Sun’s light slips through the valleys and craters of the Moon’s uneven surface, allowing a few bright points of light to shine through. The effect disappears when the Moon’s silhouette fully darkens the Sun.
Only moments before totality, a single, brilliant point of sunlight remains visible on the Moon’s rim while the corona has begun to brighten. The combination of a bright point and the faint corona creates the iconic “diamond ring” appearance. Immediately after totality, a thin strip of reddish light, the Sun’s chromosphere, encircles the Moon.
If the Moon is farther from Earth, it may pass in front of the Sun without fully covering it, producing an annular eclipse. At the peak of this event, a brilliant “ring of fire” — a band of red, orange, and yellow light — encircles the Moon, showcasing the Sun’s photosphere.
