What Are Solar Eclipses, Why Do They Occur, and How To Observe Them?

~7 min

Out of all astronomical events, solar eclipses seem to get the most attention. People around the world look forward to every next chance to see this phenomenon. In this article, we explain why solar eclipses occur, what can be seen during a solar eclipse, and how to observe it properly.


What is a solar eclipse?

A solar eclipse is a natural phenomenon that occurs when the Moon blocks all or part of the Sun's light from reaching the Earth. This results in a partial or total darkening of the solar disc, depending on the position of the Moon and the observer's location. Solar eclipses always coincide with a New Moon, because that is when the Moon gets between the Earth and the Sun.

What happens during a solar eclipse?

What happens during a solar eclipse
The Moon’s shadow seems to “travel” across different locations as the Earth rotates the Sun and as the Moon orbits the Earth.

During a solar eclipse, the Sun, the Moon, and the Earth line up in such a way that a lunar shadow falls on specific areas of our planet’s surface, creating a path of the eclipse. Since the Moon’s shadow is too small to cover the whole Earth, eclipses are only visible within this path.

Types of solar eclipses

Lunar shadow
A penumbra is the lighter outer part of the shadow. An umbra is the shadow’s central part. An antumbra is a half-shadow that begins where the umbra ends.

The Moon’s shadow can be divided into three parts: a penumbra, an umbra, and an antumbra. The type of eclipse we see depends on what part of the shadow falls on the Earth.

Partial solar eclipse

Partial eclipse
Partial solar eclipse is less dramatic than others but still offers a unique and interesting astronomical event to observe.

A partial solar eclipse is when the Moon covers only a part of the solar disc. This happens when the Sun, the Moon, and the Earth are not forming a perfectly straight line, so the Moon only casts a partial shadow or penumbra. From the areas inside the penumbra, the Sun appears as a crescent or a partially covered disс.

Total solar eclipse

Total Eclipse
During a total solar eclipse, the Moon completely blocks the sunlight, causing the sky to darken and stars to become visible. The Sun's corona, or outer atmosphere, can also be seen as a glowing halo around the Moon.

We observe a total eclipse when the Moon completely blocks the view of the Sun from the Earth, creating a total shadow or umbra. This happens when the apparent size of the Moon is larger than that of the Sun. During a total solar eclipse, the sky becomes dark as if it were nighttime, and the Sun's corona (outer atmosphere) becomes visible. Since the umbra is always surrounded by the penumbra, a partial eclipse is visible from the locations that lie just outside the totality path.

Annular solar eclipse

Annular Eclipse
During an annular eclipse, the sky doesn't turn completely dark but instead takes on a twilight hue. This type of eclipse is also known as a “ring of fire” because of the bright ring of sunlight that surrounds the Moon.

An annular solar eclipse occurs when the Moon passes between the Sun and the Earth while being at apogee (the farthest distance from our planet) or close to it. During an annular solar eclipse, the Moon casts an antumbra – the type of shadow that only exists if the light source has a larger diameter than the object casting the shadow. When the Moon is far from the Earth, it’s angular size is too small to cover the Sun completely. That’s why we see the “ring of fire” – a thin ring of sunlight around the dark lunar disc. Since the antumbra is always surrounded by the penumbra, a partial eclipse is visible from the locations that lie just outside the annularity path.

Hybrid solar eclipse

Hybrid Eclipse
For a hybrid eclipse to occur, the Moon, the Sun, and the Earth should be positioned in such a way that some parts of the Earth are exposed to the umbra, while others stay within the antumbra.

A hybrid solar eclipse, also known as an annular-total eclipse, changes from annular to total and vice versa along its path. As the Earth is round, the distance to the Moon varies from one location to another. As a result, some places (which are closer to the Moon) stay within the path of the umbra, while others (which are farther from the Moon) pass through the antumbra. Therefore, observers at different points in the eclipse path can experience either a total or annular eclipse, depending on where they are. However, you can’t see both types at once, at least from one location. Since the umbra and antumbra are always surrounded by the penumbra, you can see a partial eclipse from the locations that are just outside the path of the hybrid eclipse.

The Baily’s Beads and Diamond Ring effects

Baily's Beads
The Baily’s Beads and Diamond Ring effects occur due to the irregular surface of the Moon.

Total solar eclipse is spectacular on its own, but there are also special astronomical effects that can be observed at the same time. Since the Moon is cratered, the edge of the lunar surface is rugged. When the lunar disc is about to completely cover the Sun, the last bits of sunlight pass through the mountains and valleys of the Moon and create an array of spots, which resembles a string of beads. Hence the name Baily’s Beads – in honor of an English astronomer Francis Baily, who explained this phenomena. The Diamond Ring is observed when only one “bead” is left, appearing as a shining diamond in a glowing ring.

How often do solar eclipses occur?

Total eclipses occur approximately every 18 months, and annular eclipses – once every 1-2 years. Hybrid eclipses are the rarest, as they happen a handful of times per century, about once in a decade. In total, the world has between 2 and 5 solar eclipses every year. The last time 5 eclipses occurred in the same year was in 1935, and the next time will be in 2206.

When is the next solar eclipse?

The next solar eclipse will occur on October 2, 2024. The upcoming eclipse will be an annular solar eclipse and will pass over Argentina and Chile. After that, a partial solar eclipse will occur on March 29, 2025. It will be visible over America, western Russia, northern Asia, and north-western Africa. Download the Eclipse Guide app, and see our infographics about the 5 upcoming eclipses so as not to miss anything!

5 Upcoming Eclipses Infographics preview
List of 5 upcoming lunar and solar eclipses, their dates, timelines, and visibility maps. Find out whether you can see them from your location!
See Infographic

How to watch a solar eclipse safely?

Watching a solar eclipse can be an exciting experience, but it's important to do it safely to avoid damaging your eyes. Here are some tips:

  • Use certified eclipse glasses or solar filters. Make sure they meet the ISO 12312-2:2015 international safety standard, which means they can reduce visible sunlight to safe levels and block solar UV and IR radiation.
  • Don't use regular sunglasses or homemade filters. Regular sunglasses or homemade filters, such as smoked glass or exposed film, don’t provide enough protection.
  • Check your eclipse glasses/solar filters before using them. Make sure they are not scratched or damaged, as this can compromise their safety. Also, check the expiration date on the glasses or filter to ensure they are still safe to use.
  • Use a solar filter for telescopes and binoculars. If you plan to use a telescope or binoculars to view the eclipse, make sure to use a solar filter that fits over the front of the lens. This will protect your eyes and equipment from damage.
  • Use indirect viewing methods. If you don't have access to eclipse glasses or a solar filter, you can still view the eclipse indirectly using pinhole projectors or by projecting the image of the Sun onto a white surface.
  • Don't look directly at the Sun. Look away from the Sun while putting on and taking off your eclipse glasses or solar filter.

By following these tips, you can safely enjoy a solar eclipse without putting your eyes at risk.

It’s time to check if you’re ready to see a solar eclipse! Take our quiz to see what you know about eclipses. Also, watch this short video to visualize how solar eclipses work in action.

Man for eclipses quiz
Can solar eclipses be seen from the Moon? When was a solar eclipse first recorded on video? Test your knowledge of solar and lunar eclipses with this quiz.
Take the quiz!


When does a solar eclipse occur?

A solar eclipse occurs when the Moon passes between the Sun and Earth, blocking all or part of the Sun's light. Solar eclipses can only occur during a New Moon phase when the Moon is positioned between the Sun and Earth.

Why don’t we have a solar eclipse every month?

Not every New Moon results in a solar eclipse because the Moon's orbit is slightly tilted relative to the Earth's orbit around the Sun. Therefore, the Moon is not always in the direct line between the Earth and the Sun to create an eclipse, so the shadow cast by the Moon misses the Earth.

What’s the difference between a solar eclipse and a lunar eclipse?

A solar eclipse occurs when the Moon passes between the Sun and the Earth, casting a shadow on the Earth. A lunar eclipse occurs when the Earth passes between the Sun and the Moon, casting a shadow on the Moon. Solar eclipses occur during a New Moon, while lunar eclipses coincide with the Full Moon. During a solar eclipse, we observe the dark lunar disc passing over the Sun. During a lunar eclipse, the Moon appears reddish-orange. Get more details on lunar eclipses in this article.

How long does a solar eclipse last?

A solar eclipse can last from a few seconds to a maximum of about 7.5 minutes, depending on factors such as the location and position of the observer on the Earth and the path of the Moon's shadow across the Earth's surface.

Can you see the stars during a solar eclipse?

During a total solar eclipse, when the Moon completely covers the Sun, it becomes dark enough to see the brightest stars and planets. However, the sky won’t be as dark as it is at night. Also, because totality only lasts a few minutes, your eyes won’t have enough time to adjust to the change in light levels, so you’re unlikely to see more than the most prominent objects. By the way, comet 12P/Pons–Brooks will reach the 5th magnitude and may show up during the total solar eclipse on April 8, 2024, close to Jupiter, which will also become visible.

Is it safe to look at a solar eclipse?

It is unsafe to look directly at the Sun as it can damage your eyes with its UV and IR radiation. However, you can keep your eyes safe by using solar filters or eclipse glasses.

Do solar panels work during an eclipse?

As the solar eclipse approaches maximum phase, there will be a noticeable drop in the energy output of your panels. The lowest point will be reached during the complete eclipse, after which the power levels will start to increase again as the Moon shifts away from the Sun.

Solar eclipses: the key takeaway

Solar eclipses occur when the Moon passes between the Sun and the Earth, blocking sunlight partially or completely. Depending on the position of the Moon and the observer's location, one of the three eclipse types – partial, total, or annular – is visible. Rarely, a hybrid eclipse occurs, and some locations experience a total eclipse, while others see an annular eclipse. Get Eclipse Guide, and check Sky Tonight’s calendar and the News section to stay abreast of the latest eclipse news!