Solar Eclipse Explorer

How solar eclipses work

A solar eclipse occurs when the Moon passes between Earth and the Sun, casting a shadow on our planet. This alignment is possible because the Moon orbits Earth at a slight angle to the plane of Earth orbit around the Sun. When these orbital planes intersect at just the right moment during a new moon, the Moon shadow falls on Earth surface.

The geometry is remarkably precise. The Sun is roughly 400 times larger than the Moon, but it is also roughly 400 times farther away. This cosmic coincidence means the Sun and Moon appear almost exactly the same size in our sky — about half a degree across. This is why total solar eclipses are possible at all, and why they are so spectacular.

Types of solar eclipses

Total solar eclipses occur when the Moon completely covers the Sun disk. The Moon umbral shadow (the darkest part) touches Earth surface, creating a narrow path of totality typically 100 to 300 kilometers wide. Within this path, the sky goes dark, stars appear, the temperature drops, and the Sun corona — its outer atmosphere — blazes into view as a pearly white halo. Totality lasts anywhere from a few seconds to a maximum of about 7 minutes 30 seconds.

Annular solar eclipses happen when the Moon is near the farthest point in its slightly elliptical orbit. At this distance, the Moon appears slightly smaller than the Sun and cannot fully cover it. Instead, a bright ring of sunlight — the annulus, or ring of fire — remains visible around the Moon silhouette. Annular eclipses can last over 12 minutes at maximum, significantly longer than total eclipses.

Hybrid eclipses are the rarest type. Due to the curvature of Earth surface, the same eclipse can appear total in some locations and annular in others. As the Moon shadow sweeps across the curved Earth, the distance between the Moon and the observer changes just enough to switch between total and annular phases. Only about 5% of central eclipses are hybrid.

Partial solar eclipses occur when only the Moon penumbral shadow falls on a location. The observer sees a bite taken out of the Sun but never sees the full ring or total coverage. Every total, annular, and hybrid eclipse also produces a much larger region of partial eclipse surrounding the central path.

Understanding eclipse magnitude and gamma

Magnitude measures how much of the Sun diameter is covered by the Moon at greatest eclipse. For total eclipses, magnitude is greater than 1.0 — the Moon appears larger than the Sun. For annular eclipses, magnitude is less than 1.0. Higher magnitude total eclipses generally produce longer totality and more dramatic corona displays. The 2027 Egypt eclipse has a magnitude of 1.079, meaning the Moon will appear nearly 8% larger than the Sun.

Gamma indicates how centrally the Moon shadow strikes Earth. A gamma of 0.0 means the shadow passes through Earth exact center. Positive gamma means the shadow passes north of center, negative means south. When gamma exceeds approximately 0.997, the shadow barely grazes Earth.

The Saros cycle

Eclipses follow a pattern called the Saros cycle, a period of 6,585.3 days (approximately 18 years, 11 days, and 8 hours). After one Saros period, the Sun, Earth, and Moon return to nearly the same relative geometry, producing a similar eclipse.

Each Saros series begins with a small partial eclipse near one of Earth poles, gradually produces larger partial eclipses, then central eclipses (total or annular), and eventually fades back to small partial eclipses at the opposite pole. A complete Saros series spans roughly 1,200 to 1,500 years and produces about 70 to 85 eclipses.

The extra 8 hours in each cycle means each successive eclipse shifts approximately 120 degrees westward. After three Saros periods (about 54 years), an eclipse returns to roughly the same longitude — this is called the Triple Saros or Exeligmos.

Understanding which Saros series an eclipse belongs to helps predict its characteristics. Saros 136, which produces the 2027 Egypt eclipse, is currently in its prime generating the longest totalities it will ever achieve.

Eclipse safety

During any partial phase of a solar eclipse, looking at the Sun without proper protection can cause permanent eye damage within seconds. Solar eclipse glasses with ISO 12312-2 certification are required for all partial and annular viewing. Regular sunglasses, no matter how dark, are not safe.

During the total phase of a total eclipse — and only during totality — it is safe to look at the Sun with the naked eye. The corona is roughly as bright as the full Moon. The instant any sliver of the Sun surface reappears (the diamond ring effect), viewers must immediately put their eclipse glasses back on.

Annular eclipses are never safe to view without proper filters because the Sun surface is never fully covered.

Why eclipses matter for science

Total solar eclipses have driven major scientific discoveries. During the 1919 total eclipse, Arthur Eddington observations confirmed Einstein general theory of relativity by measuring the bending of starlight around the Sun. The corona, visible only during totality, remains an active area of research — scientists still do not fully understand why it is hundreds of times hotter than the Sun surface, a mystery known as the coronal heating problem.

Five eclipses you should not miss

The period from 2026 through 2030 offers an extraordinary lineup. The August 2026 total eclipse over Iceland and Spain is the nearest major event. The August 2027 total eclipse in Egypt will be one of the longest of the century at over 6 minutes. The January 2028 annular eclipse sets the record for longest annularity until 2050 at over 10 minutes. The July 2028 total eclipse over Sydney ends a 171-year wait for that city. And the June 2030 annular eclipse traces a path from North Africa through Greece, Turkey, and on to Japan. Use the filters above to explore each one.