Eclipse Predictor — Tutorial

How Eclipses Occur

A solar eclipse occurs when the Moon passes between Earth and the Sun, casting a shadow on Earth's surface. A lunar eclipse occurs when Earth passes between the Sun and the Moon, casting Earth's shadow onto the Moon. Both types of eclipses only occur at specific alignments of the Sun, Earth, and Moon — solar eclipses at New Moon, and lunar eclipses at Full Moon.

Not every New Moon or Full Moon produces an eclipse because the Moon's orbit is tilted about 5° relative to Earth's orbital plane (the ecliptic). Eclipses only occur when the Moon is near one of the two points where its orbit crosses the ecliptic — called lunar nodes — at the same time as a New or Full Moon.

How to Use This Tool

Enter a year between 2024 and 2030 and click "Find Eclipses." The tool displays all solar and lunar eclipses for that year, including the date, eclipse type, duration of totality (where applicable), and the geographic regions where the eclipse is visible. Use the filter buttons to show only solar eclipses, only lunar eclipses, or all eclipses.

Types of Solar Eclipses

There are three main types of solar eclipses:

• Total Solar Eclipse: The Moon completely covers the Sun's disk. The sky darkens dramatically, stars become visible, and the Sun's corona — its outer atmosphere — is revealed. Totality is only visible from a narrow path on Earth's surface, typically 100–200 km wide.
• Annular Solar Eclipse: The Moon is near apogee (its farthest point from Earth) and appears slightly smaller than the Sun. It does not completely cover the Sun, leaving a ring of sunlight visible — the "ring of fire." Annular eclipses are visible from a narrow path similar to total eclipses.
• Partial Solar Eclipse: Only part of the Sun is covered by the Moon. This is visible from a much wider area than the path of totality or annularity.

Types of Lunar Eclipses

Lunar eclipses are visible from anywhere on Earth where the Moon is above the horizon at the time of the eclipse:

• Total Lunar Eclipse: The Moon passes completely into Earth's umbra (the darkest part of the shadow). The Moon turns a deep red or orange color — often called a "blood moon" — because Earth's atmosphere refracts red sunlight onto the lunar surface.
• Partial Lunar Eclipse: Only part of the Moon enters Earth's umbra. The shadowed portion appears noticeably darker than the rest of the Moon.
• Penumbral Lunar Eclipse: The Moon passes through Earth's penumbra (the outer, lighter shadow). The dimming is subtle and often difficult to notice without careful observation.

The Saros Cycle

Eclipses repeat in a pattern called the Saros cycle, which lasts 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 very similar eclipse. This cycle was known to ancient Babylonian astronomers and allowed them to predict eclipses with remarkable accuracy.

Each Saros series produces about 70–80 eclipses over roughly 1,200 to 1,500 years before the geometry drifts too far for eclipses to occur. At any given time, about 40 different Saros series are active simultaneously.

Planning an Eclipse Observation

For total solar eclipses, the most important planning factor is being within the path of totality. The difference between 99% partial coverage and 100% totality is enormous — only totality reveals the corona and produces the dramatic darkening of the sky. Travel to the path of totality is well worth the effort.

For lunar eclipses, planning is simpler. Check that the Moon will be above your horizon during the eclipse. Total lunar eclipses last over an hour, giving ample time for observation. No special equipment is needed — binoculars enhance the view but are not required.

Weather is the primary risk for eclipse observation. Research historical cloud cover statistics for your chosen location and have backup sites identified in case of overcast skies on the day.

Eclipse Duration Explained

The duration listed in the tool refers to the period of totality or maximum eclipse. For total solar eclipses, this is the time the Sun is completely covered — typically 1 to 7 minutes depending on the geometry. For total lunar eclipses, totality can last over 100 minutes. Partial phases before and after totality extend the total event duration considerably.