Our guide to this month’s total solar eclipse over South America

2020 closes with the last total solar eclipse of the decade, as totality traverses the southern tip of South America on December 14th.

Did you happen to see the light penumbral lunar eclipse last Monday? Sure, a penumbral may be the most anti-climatic of all types of eclipses … but this event also sets us up for the ultimate astronomical events, as a total solar eclipse traverses South America on December 14.th, 2020.

This marks the end of the last eclipse season of the decade, although totality will only briefly cover a 90-kilometer stretch from Chile to Argentina.

Eclipse-Chasing, in a Time of Covid 19

This is because many an eclipse hunter has had to curtail their travel plans due to the ongoing global pandemic. The trail misses even the big cities in Chile and Argentina as it soars over the Andes mountains and graces only a few small villages as it crosses from the Pacific Ocean to the Atlantic coast of South America in about 20 minutes. The Path of Totality passes through several active volcanoes (including Villarrica in Chile), opening up several intriguing photogenic opportunities. The prospects for clear skies are best in Patagonia in central Argentina, and the chances of cloud cover increase towards the Chilean border to the west and Argentina’s Atlantic coast to the east.

The path and conditions for the December 14 total solar eclipse. Credit: NASA / GSFC.

At the time of writing, we have not yet seen any planned attempt (s) to livecast the solar eclipse from the path of totality, but we will be posting a link to any webcast that appears before the day of the eclipse.

Times for the Eclipse

The full eclipse, from the first partial phases over the remote central Pacific Ocean at 1:34 PM Universal Time (UT) to the departure of the Moon’s outer penumbra near Ascension Island in the Atlantic Ocean at 6:53 PM UT, lasts 5 hours and 19 minutes.

An animation of the solar eclipse of December 14. Credit: NASA / GSFC AT Sinclair.

The maximum duration for totality along the path of the umbra is much shorter, coming in at 2 minutes and 10 seconds near Sierra Colorado, Argentina.

Partial pre-eclipse phases stretch from Antarctica, all the way north to the Amazon River basin in Brazil and Guayaquil, Ecuador.

Here is a selection of conditions for sub-stages from the region:

Location: partial percentage / time

Palmer Station Antarctica: 30% / 4:28 UT

Falklands: 70% / 16:32 UT

Buenos Aires: 82% / 16:29UT

Santiago, Chile: 80% / 16: 02 UT

Montevideo, Uruguay: 78% / 4:33 PM UT

La Paz, Bolivia: 30% / 15: 50UT

Asuncion, Paraguay: 45% / 4:27 UT

Lima, Peru: 25% / 15:22 UT

Rio de Janiero, Brazil: 41% / 5:15 pm UT

Stories of the Saros

A solar eclipse occurs when the moon passes between the Earth and the sun near one of the nodes intersecting the ecliptic plane, and must by definition occur in the new phase. Next Monday’s total solar eclipse is member 23 of 72 eclipses in solar saros cycle 142, which runs from 1624 to 2904. This cycle just started producing total eclipses at 1786.

If you are lucky enough to be in the shadow of the moon on the 14thth, be sure to view brilliant Venus 24 degrees west of the sun, and Jupiter approaching Saturn for a historic 6 ‘conjunction on December 21st, only 35 degrees east of the sun on the day of the solar eclipse. Another special guest may also emerge: Comet C / 2020 S3 Erasmus, beaming at +4th to +5th size. The comet is only 11 degrees from the eclipsed sun, fresh from perihelion on December 12.

The sky line at the center of the eclipse. Credit: Starry Night.

As a sort of cosmic consolation prize, the slender waning crescent moon will also occult (before) Venus for the northwestern Pacific and far east of Russia on the morning of December 12, less than 48 hours prior to the eclipse.

Occultation path
The footprint of the December 12 occultation of Venus by the moon, prior to the total solar eclipse. Credit: Occult 4.2.

What does the corona look like? That’s always an important question, as the shape and intensity of the sun’s outer atmosphere can indeed vary from one solar eclipse to the next. Eclipse hunters can actually look at photos of previous eclipses and tell you which eclipse they came from.

The predicted shape of the corona during this month’s total solar eclipse. Credit: Predictive Science, Inc.

The sun is also awakening from its long sleep. Last week we had another massive sunspot, easily the largest to date for the current otherwise matte solar cycle # 25. Although it has since turned out of sight, we could easily expect more, adding to a very photogenic solar eclipse during the partial stages. What comes into view for the next week will be visible on the terrestrial side of the sun on the day of the solar eclipse.

solar eclipse
Observation of the 2017 Total Solar Eclipse. Credit: Dave Dickinson.

Are we getting a view of the eclipse … from space? It is not out of the question, since several solar observation missions also occasionally capture images of eclipses from orbit. One such high-flying mission is the European Space Agency’s Proba-2 Observatory:

Finally, if you are lucky enough to personally observe this month’s total solar eclipse, make sure to practice proper solar eclipse observation and safety. Use appropriate ISO 12312-2 certified eclipse goggles during all partial eclipse phases and use appropriate filters for solar observation on all optics. NASA has a good page devoted to the safety of solar observation. An interesting option is to build a safe binocular sunscreen using a tea box and an extra set of eclipse glasses:

When is next? Well, 2021 will host two solar eclipses: an annular solar eclipse that will cross the North Pole on June 10th, and a total solar eclipse over Antarctica on December 4th.

Hopefully, by then, travel around the world will reopen so that we can see the totality again in person.

Main Image Credit: The 2017 Total Solar Eclipse. Credit and Copyright: Sharin Ahmad.

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