TOTAL SOLAR ECLIPSE
WHAT TO EXPECT AND HOW TO SEE IT
On 2 July 2019, the Sun will be completely blocked out by the Moon, making for one of nature’s finest blackouts
Blackouts aren’t usually an event that people look forward to, but when a total solar eclipse occurs, people come from all over the world to embrace every second. Although there are lunar eclipses – where the Moon enters Earth’s shadow, or ‘umbra’, behind the Sun – and planetary eclipses – normally associated with the transits of Venus and Mercury – nothing can beat a total solar eclipse.
On 2 July 2019 South America will host a total solar eclipse, which at 100 per cent totality – a term used when the Moon completely blocks out the Sun, or vice versa – will span 200 kilometres (125 miles)
across the South Pacific Ocean, Chile and Argentina. Other countries in South America will be able to experience a partial eclipse, such as Paraguay, Bolivia, Brazil, Peru and Colombia.
Full eclipses are extremely rare as they require a new Moon, which then needs to cross paths with the Sun as it moves around the sky in what is also known as the ecliptic. Due to a celestial coincidence, the Sun and Moon are roughly the same size, which is approximately half a degree. To put that into comparison, that is about half the size of your little finger held at arms length away from you. When this event lines up, it leads to a brief period of a world without the Sun.
August 2017 saw the solar eclipse dubbed
‘The Great American Eclipse’, its path of totality stretching from the West to the East Coast across the United States, as well as the Pacific and Atlantic Oceans. Almost two years later the world is about to bear witness to another eclipse that will not only create an amazing spectacle for general members of the public, but also provide scientists with an opportunity to study the most elusive and intriguing area of the Sun: its corona.
The eclipse will begin as a partial eclipse at 16:55 GMT (12:55 EDT) over the Pacific Ocean before totality will begin to cast a shadow on the land over Oeno Island – a British territory making up part of the Pitcairn Islands in the South Pacific Ocean – at 18:24 GMT (10:24 PST). From there it will travel southeast through La Serena in Chile and San Juan, Río Cuarto, Venado Tuerto, Junín and Pergamino in Argentina. It will just miss Buenos Aires, Argentina, and Montevideo, Uruguay, as it travels south of these cities. The end of totality will reach the Atlantic Ocean just before sunset at 20:40 GMT (17:40 ART).
The south of Uruguay and the capital of Chile, Santiago, can still experience a large majority of the Sun being blocked out, at least 90 per cent, in fact. A partial eclipse is caused when the Moon creates a ‘penumbral shadow’, casting a less intense shadow on Earth’s surface. Places as far as French Polynesia, south Peru and Bolivia could even see at least 50 per cent coverage. However, it is the 100 per cent totality that produces the most awe-inspiring views, and that is why people will flock towards its path through Chile and Argentina.
Weather is a factor that must always be taken into account when planning an outdoor observing trip such as this one. Of course, cloud coverage is something that simply can’t be determined far in advance, but it is worth taking into account that South America will be experiencing austral winter. This means the Andean region has the best chances of viewing at high altitudes, as it will hopefully have incredibly clear skies and low humidity. Although, as the eclipse moves towards the horizon towards eastern Argentina, clouds may interfere with the view of a low-altitude Sun.
Safety when observing the Sun is key. The light released by the Sun can be very damaging to your eyes, and it is important to emphasise that the eclipse can only be viewed with the naked eye during complete totality. Before and after the eclipse, viewing must be done with the help of certified-safe solar eclipse glasses, solar filters that can be attached onto binoculars or a telescope or even a colander, as it can project the light, and therefore the light crescents, onto a sheet of white paper.
Those fleeting moments of totality are marvellous as darkness takes over, providing the rare opportunity to observe the white-hot corona emanating from the outer region of the
Sun. Just as the eclipse occurs, there is also the chance to see the famous diamond ring, a term given to the moment when the Sun’s last light is gleaming as a faint ring surrounding the Moon.
The European Southern Observatory (ESO) has prepared an event at its La Silla Observatory in the Atacama Desert in Chile, just north of La Serena. With a host of diligent telescopes, the organisation has opened its doors to the public to watch the solar eclipse, as it falls in the path of totality. People will be able to watch a total eclipse of the Sun, along with other activities, the observatory flaunting the fact that its high altitude of 2,400 metres (7,900 feet) means the solar eclipse will bring out an array of bright stars and planets around the eclipse, including Mars, Betelgeuse, Procyon, Sirius and a few others.
You don’t need to be in the path of totality to observe such an amazing occasion, either, as different organisations are preparing live streams of the event to broadcast around the world. The ESO will have a stream available closer to the occasion, as will the Slooh Observatory, Exploratorium and similar YouTube live-streaming channels.
“Weather is a factor that must always be taken into account when planning an outdoor observing trip such as this one”