Illustrated Astronomy/Watching eclipses safely
VIII WATCHING ECLIPSES SAFELY
There is no need to use safety measures to watch a lunar eclipse so that this section focuses on solar eclipses.
Watch directly at the Sun is harmful to our sight. The brightness is so intense that our retina can be irreversibly damaged. So, if we want to watch the Sun directly, we must do it using the right implements. Then, during the total solar eclipse, it is not necessary to use any protection, you can watch directly without glasses and is NOT harmful, but before the totality and right after, we should protect ourselves.
WATCHING THE SUN INDIRECTLY
The safest way to watch the Sun is by watching it indirectly. To do so, you can take any paper sheet and cut a tiny hole (of 0.5 mm, for example). Then, point to the Sun and see how the light goes through the hole, projecting onto another surface, which can be another paper, a wall, the ground, etcetera. The closer, the smaller is seen, but intense. If you put the paper away, it is blurrier but bigger.
WATCHING THE SUN DIRECTLY (AND SAFELY)
There are different ways to watch the Sun directly, with or without zoom. In the case of no using zoom, we can get glasses specially designed for it. It is imperative to have certified glasses to avoid retina damages; you must ensure the glasses block the 99,999 % of the solar light.
If you decide to watch the Sun with zoom, you can do it using binoculars or telescopes well equipped with filters specially designed to watch the Sun. There are two types of filters:
1 · “Gray” filters or neutral density filters, which block all the light equally and create a sight of the Sun as seen with glasses. You can see the Sun a bit bigger, and perhaps you distinguish its solar spots.
2 · Narrowband filters, particularly hydrogen-alpha filter, which block all the light except a very particular reddish color that allows the solar chromosphere, solar spots, eruptions or solar flares, and granulation to stand out. The telescopes full equipped with these filters are suitable to watch the Sun all the time, but they are not a great advantage during an eclipse.
At the same time, but irresponsibly, is has been suggested to use CD, X-ray photographies, smoked glasses, sunglasses, polarized glasses, the old diskettes inner disk, ribbon cassettes, aluminum foil, among others. The truth is that none of these elements are suitable to watch direct and safely the Sun since the amount of light passing through them can damage the sight beyond repair.
DO NOT USE
· CD
· X-RAY PHOTOGRAPHIES
· SMOKED GLASSES
· SUN GLASSES
· POLARIZED GLASSES
· OLD DISKETTES INNER DISK
· CASSETTES RIBBON
·ALUMINUM FOIL
Watching a total eclipse of the Sun is an unforgettable experience. As we reviewed in the preceding section, these are relatively common phenomena in the world. However, they can’t always be seen from any city since, sometimes, they happen in the poles or the middle of the ocean. That’s why when it is visible on solid ground, thousands of people travel to watch them.
| VISIBLE ECLIPSES FROM CHILE IN THE 21ST CENTURY | ||
| Date | Region | Total time |
| July 11th, 2010 |
Valparaiso (Easter Island) and Magallanes and the Chilean Antarctic |
5 min 20 s |
| July 2nd, 2019 | Coquimbo and Atacama | 4 min 32 s |
| December 14th,
2020 |
La Araucania and Los Rios | 2 min 10 s |
| December 4th, 2021 | Magallanes and the
Chilean Antarctic |
1 min 54 s |
| December 5th, 2048 | Aysén del General Carlos
Ibáñez del Campo and Los Lagos |
3 min 28 s |
| August 12nd, 2064 | Valparaiso, Metropolitan
Region, and Libertador Bernardo O’Higgins |
4 min 28 s |
| August 3rd, 2073 | Magallanes and the
Chilean Antarctic |
2 min 29 s |
| January 16th, 2075 | Coquimbo | 2 min 42 s |
*The eclipses on April, 20th of 2023 and November, 14th of 2031 are hybrid, which means that from some places will be a total eclipse, while in others annular.
| DATES AND PLACES OF THE NEXT
TOTAL SOLAR ECLIPSES UNTIL 2040 | ||
| Eclipse date | Place | Total time |
| July 2nd, 2019 | Chile and Argentina | 4 min 33s |
| December 14th,
2020 |
Chile and Argentina | 2 min 10s |
| December 4th, 2021 | Antarctic | 1 min 54s |
| April 20th, 2023 * | Indonesia, Australia,
Papua New Guinea |
1 min 16s |
| April 8th, 2024 | Mexico, EEUU,
Canada |
4 min 28s |
| August 12th, 2026 | Artic, Greenland,
Iceland, Spain |
2 min 18s |
| August 2nd, 2027 | Morocco, Spain,
Algeria, Lybia, Egypt, Saudi Arabia, Yemen, Somalia |
6 min 23s |
| July 22nd, 2028 | Australia, New
Zeeland |
5 min 10s |
| November 25th,
2030 |
Botswana, South
Africa, Australia |
3 min 44s |
| November 14th,
2031* |
Panama | 1 min 08s |
| March 30th, 2033 | Russia, Alaska | 2 min 37s |
| March 20th, 2034 | Nigeria, Cameroon,
Chad, Sudan, Egypt, Saudi Arabia, Iran, Afghanistan, Pakistan, India, China |
4 min 09s |
| September 2nd,
2035 |
China, Korea, Japan | 2 min 54s |
| July 13th, 2037 | Australia, New
Zeland |
3 min 58s |
| December 26th,
2038 |
Australia, New
Zeeland |
2 min 18s |
| December 15th, 2039 | Antarctic | 1 min 51s |
*Data obtained from https://eclipse.gsfc.nasa.gov/solar.html