WATCH: Here’s how to see the last solar eclipse of the year on 4 December

The solar eclipse on 4 December 2021 – also known as a ‘reverse polar’ solar eclipse – will be partially visible from parts of South Africa and South America.

Those in the path of a solar eclipse will experience a few seconds – or, in some cases – up to several minutes of twilight.

Solar eclipse 2021

According to Nasa, those residing at the Palmer Station and in Emperors Point in Antarctica will have the best seats to this show on 4 December.

Will the eclipse be visible from South Africa?

Only partially. Viewers from parts of South Africa, Namibia, New Zealand and South America will experience a partial solar eclipse.

This means the Sun, Moon and Earth will not line up exactly, and the “Sun will appear to have a dark shadow on only part of its surface”.

Even though it will be a partial eclipse for people residing in South Africa, there’s still a way to view the eclipse, though, and from the comfort of your home.

Watch: Solar eclipse live feed

Weather permitting, Nasa TV will air a live stream of the eclipse, as seen from the Union Glacier in Antarctica. It will start at 8:30 South African Standard Time (SAST).

From our point of view in South Africa on 4 December, only 12% of the Sun will be covered, those in Cape Town will have the best chance of seeing the eclipse.

When is the next solar eclipse

Several other solar events will occur over the coming decade, including both an annular and total eclipse in 2023. Unfortunately, none of those will be visible from South Africa.

The next eclipse visible from the southern hemisphere will take place on 25 November 2030. The next two after that will only be visible in August 2046, and again on July 2055. 

The next annular solar eclipse will only be visible on 24 October 2060, and the one after that will roll around again on 23 April 2107.

What is a solar eclipse?

According to Nasa, a solar eclipse happens when the Moon moves between the Sun and Earth, casting a shadow on Earth which either fully or partially blocks the Sun’s light.

“For a total solar eclipse to take place, the Sun, Moon, and Earth must be in a direct line. People located in the centre of the Moon’s shadow when it hits Earth will see a total eclipse.”

During a total eclipse, the sky becomes very dark, “as if it were dawn or dusk”. The closer you are to the central line of the totality, the darker it will be in your region.

People in the path of a total solar eclipse can see the Sun’s corona, the outer atmosphere. The corona is otherwise usually obscured by the bright face of the Sun.

A partial solar eclipse happens when the moon doesn’t block the sun entirely.

Why is it called a ‘reverse polar’ solar eclipse

In the simplest terms, the Moon’s shadow will “go backwards”. Most eclipses go from west to east, as the stars and other celestial bodies rise in the east.

But the moon orbits Earth in the opposite direction. While the Earth’s shadow on the Sun would under normal move from west to east, it will be mirrored on 4 December.

Forbes’ science guru, Jamie Carter, says the “path of totality curves across the lines of longitude and moves ‘backwards’ – from east to west – because the South Pole is tilted towards the Sun”.

Safety measures

If you are in the line of totality, the general rule is not to stare directly at the Sun. However, there’s an exception. Only when the Sun is completely hidden from view, will you be able to stare directly at it and witness the corona.

Apart from that brief window, you must wear proper eye protection or specialised glasses to look at the Sun. If you don’t, you will suffer long-term or even permanent damage to your vision.

Inspect your solar filter or solar glasses before using them. Always make sure that the glasses you purchase are ISO certified. Make sure there are no holes in the lens or are damaged in any way.

You can use older glasses if it isn’t broken. If you wear prescription eyeglasses, wear solar glasses over them to view the eclipse. Only remove the eclipse glasses after you have looked away from the sun.