Your guide to enjoying eclipses

VERY IMPORTANT! Looking directly at the Sun, without appropriate protection, can lead to serious problems such as partial or complete loss of eyesight.

Artist's rendition of a total solar eclipse. (Credit: CSA)

An eclipse is a wonder to behold. Although eclipses occur more often than you might think, there aren't many opportunities to admire them. There are four to seven eclipses per year, but only those people along the path of an eclipse are able to see it.

What is an eclipse?

An eclipse occurs when the light of a body outside Earth's atmosphere (Sun, Moon, planets, etc.) is temporarily blocked by another body. Eclipses don't just happen on Earth: they also take place on other planets, like Jupiter and Neptune.

What is a solar eclipse?

A solar eclipse occurs when the Moon comes between the Earth and the Sun, casting a shadow on Earth.

Animation of a solar eclipse (Credit: NASA)

From the locations along the Moon's umbra trajectory, it appears as if the Sun has gone dark. Depending on the distance between the Sun and the Moon and their positions, it is possible to see three kinds of solar eclipses:

Artist's rendition of a total solar eclipse. (Credit: CSA)

Artist's rendition of an annular solar eclipse. (Credit: CSA)

Artist's rendition of a partial solar eclipse. (Credit: CSA)

How to safely watch a solar eclipse

During any solar eclipse, it is imperative to wear special glasses with filters designed for eclipse watching (ISO 12312-2 international standard) to prevent eye damage. Regular sunglasses will not protect your eyes sufficiently.

Watching a Solar Eclipse - Grand Canyon Park visitors observed an annular solar eclipse in May 2012. (Credit: US National Park Service)

During a total solar eclipse, the path of totality is a narrow corridor approximately 100 to 115 km wide where the Sun appears to be completely covered by the Moon for a short period of time (between 2 and 3 minutes). This is the most spectacular part of the eclipse, as those who are lucky enough to be in this corridor are able to see the Sun's corona, the chromosphere, prominences and streamers. Proper eye protection is essential before and after totality.

For those outside the path of totality, the Sun appears to be partially covered by the Moon (partial eclipse). When watching a partial solar eclipse, proper eye protection is required at all times.

If you don’t have special glasses designed for eclipse watching, there are other ways to watch an eclipse, such as an eclipse projector, which you can easily learn how to make.

Solar eclipse projector – How to build your own eclipse projector. (Credit: Canadian Space Agency)

When will the next total solar eclipse be visible in Canada?

The next total solar eclipse to be visible in Canada will occur on April 8, 2024, when the path of totality will cross Mexico, the United States and eastern Canada.

Total solar eclipse of August 21, 2017

On August 21, 2017, a total solar eclipse crossed the entire United States (from west to east). Fourteen US states were lucky enough to witness it in its totality, and the other US states and Canada were treated to a partial eclipse.

In Canada, a partial eclipse could be seen from almost every Canadian city. See the map below to find out how much of the Sun's surface was covered by the Moon and at what time it will occurred depending on your location.

Time of maximum eclipse for different cities in Canada. (Credit: Canadian Space Agency)

What is a lunar eclipse?

A lunar eclipse occurs when Earth is in between the Moon and the Sun. The Moon passes through the shadow cast by Earth. This phenomenon can only happen during a full moon, when the Moon is on the opposite side of Earth than the Sun. Unlike solar eclipses, lunar eclipses can be seen by practically an entire hemisphere, which means that a much larger number of people can see them for a longer period of time.

Animation of a lunar eclipse (Credit: NASA)

During a lunar eclipse, Earth's shadow consists of the umbra (inner part, where there is no sunlight) and the penumbra (outer part, where there is some sunlight). Depending on the Moon's trajectory, there can be three different types of lunar eclipses:

Lunar eclipse - Different stages of a lunar eclipse. (Credit: NASA/Rami Daud)

A total lunar eclipse will go through all three stages and will last between 30 and 60 minutes. Even during a total lunar eclipse, the Moon is never completely invisible. Sunlight is refracted through the Earth's atmosphere and gives the Moon a red hue, which is where the name Blood Moon comes from. It is always safe to observe a lunar eclipse with the naked eye. No special eye protection is necessary.

The next total lunar eclipse visible from Canada will occur on January 31, 2018 (western North America).

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