How does a solar eclipse occur?

A solar eclipse occurs when the Moon is in the new phase between the observer and the Sun, partially or completely obscuring the Sun's disk. Because the Moon orbits our planet in an orbit slightly inclined to the plane of the Earth's orbit (the deviation is about 5°), more often than not, a new Moon will miss the solar disk in the daytime sky and no eclipse will occur. Only about once every six months or so does the New Moon come very close to the imaginary straight line between the Earth and the Sun in its orbit, and some people on Earth can observe this phenomenon.

The farther the observer is from the conical shadow of the Moon, the smaller percentage of the Sun is obscured during the phenomenon. The area of visibility of a partial eclipse never covers the entire hemisphere of the Earth where the day is, and thus a partial eclipse is not visible everywhere during a particular event. In the case of the March 29th, 2025 eclipse, it is only a partial eclipse; the full lunar shadow will not reach the Earth's surface anywhere. The eclipse will be most pronounced in Canada, with a partial eclipse of 94.8 per cent in northern Quebec.

How will the solar eclipse take place on March 29th?

The phenomenon will start around 11:29 CET (the start time varies in minutes in different places). At that time, the silhouette of the dark New Moon will begin to "bite" into the solar disk from the right edge. The further east you are, the later the partial eclipse will start and the smaller the eclipse will be. The peak of the phenomenon will occur between 12:15 and 12:23 CST, depending on the observer's position. The end of the eclipse will be around 1pm, also depending on the observer's position. The Sun will be very high above the southern horizon for the duration of the phenomenon.

Below is a table with the visibility of the phenomenon in selected Czech cities. For details of the phenomenon in your chosen location, just visit Xavier Jubier's interactive map and select your location on the map. You need to equip yourself with a special filter for eye protection (see below). You can also find more detailed information about this phenomenon and other solar eclipses to come in the coming years in the book Mysterious Eclipses.

Solar eclipse viewing safety

When observing solar eclipses, as well as sunspots and other phenomena associated with direct viewing of the Sun, it is absolutely necessary to follow the safety rules. Looking directly at the Sun, even if it is partially obscured by the Moon, can cause serious or even permanent damage to your eyesight. In general, there are several methods of viewing the Sun indirectly (by projection, live video streaming, etc.). Direct observation - with the naked eye or binoculars - always requires the use of a suitable filter. Below is a list of possible and available filters that can dim the sunlight and allow you to observe the phenomenon safely:

Public viewing of the solar eclipse on 29th March 2025:

Many observatories will offer viewing of the phenomenon with large telescopes with filters, weather permitting. For those who would like to observe the phenomenon with expert commentary and large telescopes, a list of eclipse events is available on the Czech Astronomical Society website.

Interesting facts

Coincidentally, there has already been one solar eclipse on the same date in this century. It occurred on March 29, 2006 and was observed as complete by many domestic enthusiasts and professional astronomers, especially in Turkey and Libya. In central Europe it was observed as a partial one of about 50% magnitude.

You don't need binoculars to see a partial solar eclipse - just a tree. In fact, if you are near a tree with a lush crown, you will see a large number of small images of the Sun in its shadow due to the pinhole effect. If there is no tree nearby, just leave your clenched fist slightly open and let the sunlight penetrate through it into the shadow of your fist on the ground. A small disc of light will be "bitten off" just like the sun's disk in the sky. The phenomenon is called camera obscura, and you can easily make a more sophisticated eclipse-viewing instrument using this principle.

The next solar eclipse we will see from the Czech Republic will take place next year on August 12th, 2026, and will be the largest partial eclipse visible in Central Europe until July 13th, 2075. Those who go to Spain to see it will see it as total. It will also be the closest total solar eclipse to the countries of central Europe until 2081.

Contact details:

Mgr. Petr Horálek

Pavel Suchan

RNDr. Tomáš Gráf, Ph.D.