On the 2nd of July 2019
a total solar eclipse occurred over
ESO’s La Silla Observatory in the Chilean
Atacama Desert.
ESO invited nearly 25 scientists,
communicators and educators to observe
and document this rare occasion from
La Silla.
ESOcast Episode 209 // Outreach and Science During the Total Solar Eclipse at La Silla
Total solar eclipses are rare phenomena
and only occur, on average,
once per 360 years
in a specific location
Historically, total solar eclipses
have only been observed twice from large
professional observatories: in 1961 over L’Observatoire de Haute-Provence
in France and in 1991
over Mauna Kea on the island of Hawai’i.
These events have a great impact on the people
fortunate enough to experience them
and also allow for special science experiments
to take place
For this reason, ESO let nearly 25 scientists, communicators and educators
observe and document the eclipse
from La Silla, supported by the ESO
Communication Department and benefitting from
La Silla’s clear skies, infrastructure
and resources.
Along with cameras and telescopes from 700
members of the public, and more than 60 journalists,
five different groups conducted outreach,
education and science experiments on the day.
They were assigned a place on the flanks of the La Silla mountain
just below the Visitor Centre
as well as on a platform next to the New Technology Telescope
or NTT for short.
Naturally, expectations were high….
Our experiment features seven cameras and five
telescopes and we are trying to cover several
aspects of solar science, solar education
and outreach …
With our experiments, we will try to study
and understand better the inner part of the corona,
the atmosphere of the Sun and its chromosphere.
This telescope will observe the Sun
during the eclipse in order to measure
the position of stars around the Sun
for measuring the effect of general relativity
This eclipse is very practical for me because we repeat exactly the same experiment
that one century ago by
Eddington for the demonstration of general relativity.
My experiment is going to measure the linear polarisation of the solar corona.
The corona changes with each eclipse and that is what we’re trying to study; how it changes.
I think we can probably determine how the corona is changing with the activity of the Sun.
The Sun is going into a minimum state
and then the activity will increase in a few years.
We can actually see how the corona changes with that.
The NTT — one of the two 4-metre
class telescopes at La Silla, was also pointed
daringly near the Sun during the eclipse
Its is very exciting to observe the eclipse from here,
from La Silla because we can use a very powerful
telescope, a 3.5-metre diameter telescope,
which allows to look for very fine features in the solar corona.
Thanks to the NTT, the powerful telescope, we may discover
new spectroscopic lines in the solar corona
and then get new information about the Sun.
You have to be very careful when you use such a large telescope
aiming at the Sun. We trust the people from here, from
La Silla, to operate and to move quickly
the telescope when the Sun will again reappear.
And then the great moment came:
The moment of totality
Two webcasts and a Google hangout were done
and included a special 4-hour long webcast
following the progression of the entire eclipse
All the way down to the sunset,
even including a green flash!
The experiments conducted during the total solar eclipse
enabled some great and rare results.
Stars around the eclipsed Sun were observed
to show the deflection of starlight due to
the Sun’s monumental gravitational field
and thereby confirm the general theory of relativity.
The first-ever measurements of the Earth’s ionosphere
were done to try to record changes caused
by the Moon’s shadow transit to reveal
ionospheric irregularities during the eclipse.
Polarisation measurements produced a map of the polarisation of the corona. There is less
polarisation at the Sun’s poles and the most at the solar equator.
Interesting features were found in spectra
taken of the Sun from the elements iron,
calcium, helium and hydrogen.
Observing and documenting the total
solar eclipse over the La Silla Observatory
was a breathtaking experience for all involved.
The contributions and findings of the 25
scientists, communicators and educators
will help to deepen our understanding of
these rare phenomena.
And the NTT survived without going up in flames...