The annular eclipse of January 15, 2010: the longest ring of fire of the century

Superb annular eclipse of January 15, 2010 — Annular solar eclipse of January 15, 2010 observed in Jinan, China. That day, the Moon was almost at its apogee, that is, at its farthest point from Earth, at about 405,000 km. At such a distance, its apparent diameter was smaller than that of the Sun. The maximum duration of annularity, reached when the Moon is most perfectly aligned with the Sun, was about 11 min 8 s, making it one of the longest of the millennium.
Image source: Wikimedia Commons (new window), public domain.

Scientific summary

The Astronoo article presents the annular eclipse of January 15, 2010, the longest of the third millennium, with a maximum annularity of 11 minutes and 8 seconds. Astrophysicists explain this phenomenon by the position of the Moon at its apogee, about 405,000 kilometers from Earth, a distance at which its apparent diameter becomes smaller than that of the Sun. The path of centrality crossed Central Africa, the Indian Ocean, India, Sri Lanka, Burma and China. Observations filtered in H-alpha revealed the granular texture of the solar photosphere, offering a natural laboratory for the study of the inner corona.

Why is the annular eclipse of January 15, 2010 considered one of the most spectacular of the millennium?

This article is devoted to the annular eclipse of January 15, 2010, an astronomical event that crossed three continents and lasted more than eleven minutes at the point of greatest annularity. But what makes this eclipse so special for astronomers? The answer lies first in the orbital geometry of the Moon: it was then near its apogee, at about 405,000 kilometers, so that its apparent disk, smaller than that of the Sun, could not occult it completely. A ring of fire therefore remained visible around the lunar silhouette. The second reason is the duration: with 11 minutes and 8 seconds of annularity, the 2010 eclipse set a record for the third millennium, which allowed prolonged and detailed observations. The trajectory, which began in Central Africa and ended in China, offered scientists a rare opportunity to study the solar photosphere in H-alpha light and to test models of Earth-Moon-Sun orbital dynamics.

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Description of the annular eclipse

A ring of fire in the sky

Annular eclipses occur when the Moon is near its apogee, that is, the point of its orbit where it is farthest from Earth. The greater distance makes the Moon appear smaller in the sky, which prevents it from completely covering the Sun, thus leaving a ring of solar light visible around it.

The special case of January 15, 2010

The annular eclipse of January 15, 2010 was a remarkable astronomical phenomenon: the Moon covered the center of the Sun, leaving a solar ring visible, often called a "ring of fire". This type of eclipse occurs when the Moon is too far from Earth to completely cover the Sun.

Path and visibility

A journey from Central Africa to China

This eclipse was visible mainly in parts of Africa, Asia and the Indian Ocean. The eclipse path began in Central Africa and moved eastward across the Indian Ocean, India, Sri Lanka and Burma before ending in China.

A record annularity of eleven minutes

The maximum duration of the annularity was about 11 minutes and 8 seconds, making it the longest annular eclipse of the third millennium.

Characteristics of the annular eclipse of January 15, 2010

The table below summarizes the main characteristics of the annular eclipse of January 15, 2010, from its type to its trajectory.

Characteristics of the annular eclipse of January 15, 2010
Characteristic	Value	Description
Type	Annular	The Moon does not completely cover the Sun
Date	January 15, 2010	Date of the eclipse
Maximum duration	11 minutes and 8 seconds	Longest duration of annularity
Path	Africa, Asia, Indian Ocean	Regions where the eclipse was visible

References

FAQ: Everything you need to know about the annular eclipse of January 15, 2010

What is an annular eclipse?

An annular eclipse is a type of solar eclipse that occurs when the Moon is too far from Earth to fully hide the solar disk. A luminous ring, called a "ring of fire", then remains visible around the lunar silhouette. Unlike a total eclipse, the solar corona is not observable, but the photosphere remains partially accessible.

Why did the eclipse of January 15, 2010 last so long?

The exceptional duration of 11 minutes and 8 seconds is explained by the conjunction of several factors: the Moon was near its apogee, the Earth was near its perihelion and the alignment of the three bodies was almost perfect. This set of conditions kept the Moon centered on the solar disk for a record period for the third millennium.

Where was the annular eclipse of January 15, 2010 visible?

The path of centrality crossed Central Africa, the Indian Ocean, India, Sri Lanka, Burma and China. A partial eclipse was, however, observed in a vast region covering Africa, the Middle East, South Asia and East Asia.

What is the difference between an annular eclipse and a total eclipse?

In a total eclipse, the Moon is close enough to Earth to fully cover the solar disk, revealing the corona. In an annular eclipse, the greater distance of the Moon makes its apparent diameter smaller than that of the Sun, so that a ring of light remains permanently around it.

Can an annular eclipse be observed without protection?

No. At no point during an annular eclipse, even at maximum, is it possible to look at the Sun with the naked eye without risk of irreversible retinal injury. Only certified ISO 12312-2 filters, or indirect projection, allow safe observation.

When will such a long annular eclipse occur again?

An annularity of more than eleven minutes will not occur again for several centuries. Long annular eclipses remain rare, as they require a precise alignment between a Moon near its apogee and an Earth near its perihelion. The next records of this kind are expected beyond the fourth millennium.