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If you’ve ever been lucky enough to look up
and see bright lights dancing across the night sky,
you’re familiar with one of the planet’s most dazzling natural displays: the auroras.
And for a long time, these light shows were pretty mysterious.
But the late physicist Joan Feynman helped us understand the origin of these light shows.
She also figured out that they can reveal clues about the Sun,
as well as about the surprising connections between our planet and the star we orbit.
Joan Feynman was born in 1927 in Queens, New York.
You may already recognize her last name and associate it with science,
and that’s no coincidence.
Her brother was Richard Feynman, one of the most famous physicists of the 20th century.
But before he was a famous physicist, he was a brother.
And he would often talk with his younger sister about science.
He was the one to take her out to a golf course near their house in Queens
to see her first aurora when she was five or six.
What neither one of them knew at the time was that this experience
would later inspire her career:
in particular the decades she would spend working on the physics underlying auroras.
After graduating with a PhD in solid state physics from Syracuse University in 1958,
Joan Feynman got to work, trying to understand what drives these polar light shows.
For about 100 years, astronomers had suspected a link
between the Sun’s activity and auroras.
In 1859, they spotted a huge solar flare,
and then two days later telegraph wires started heating up
and bright auroras extended as far south as the Carribean and Hawaiʻi.
But it wasn’t until we started sending scientific instruments to space on satellites
in the 1960s that we could really figure out what was going on.
And Feynman and her collaborators were the first to do so.
In 1977, they used 14 years’ worth of satellite data
to show that there was a close link between the intensity of geomagnetic activity,
such as auroras,
and the speed of the charged particles streaming from the Sun,
known as the solar wind.
The most activity, and the most dazzling auroras,
always happened during the most tumultuous times on the Sun.
So there was no longer any question that auroras were caused by the Sun.
And armed with that insight, Feynman was able to
gain a greater understanding of the Sun’s long-term patterns.
See, previous researchers had noticed that the Sun goes through
an 11-year cycle of high and low activity caused
by a switching of the Sun’s north and south poles.
But there also seemed to be a longer,
88-year cycle running underneath the shorter one.
For about half of that cycle, the peaks
and troughs in solar activity seemed to rise;
then for the next half of that cycle, all the peaks and troughs seemed to fall.
But we didn’t exactly have solar data going back for hundreds of years,
so it was a little hard to verify.
Instead, in the late 1970s and early 80s,
Feynman and other researchers used historical observations of auroras
to figure out what the Sun’s activity was like at different points in time.
They knew that when the Sun is more active,
it makes more, brighter auroras happen further from the poles.
So they could infer when it was most active based on recorded observations of auroras.
And through this method, they were able to confirm that the 88-year cycle really exists.
Aside from being generally interesting,
that’s also helpful to know because the Sun’s activity
can have a big impact on us here on Earth.
A rush of charged particles can disrupt our telecommunications and electrical systems.
Like, during a peak of solar activity in 1989,
a burst of hot plasma from the Sun caused a 12-hour blackout for all of Quebec.
So, understanding those patterns can help us be better prepared.
But Feynman’s later research suggests
there are even more ways the Sun’s activity affects us here on Earth.
In 2006, Feynman’s knack for finding patterns led
her to discover a connection between solar activity and the water level of the Nile.
It just so happens that the people living by the Nile kept
very close track of this river for many centuries.
Because of this, there are good records of its water levels for almost 1000 years,
between 622 and 1470 C.E.
And when Feynman and her collaborators
matched that up with historical aurora records for the same time period,
they found a surprising correlation.
Both the patterns of the auroras and the water levels
in the Nile aligned with an 88-year cycle.
When the Sun was active and there were lots of auroras,
the water levels were low. When it was less active, the water levels were higher.
It may sound far-fetched, but there is a good physical reason to believe it’s real.
In the 1990s, other researchers used modern climate models
to show how variations in UV light could mess with the balance of ozone in Earth’s upper atmosphere.
That, in turn, could affect temperature patterns
and cause ripple effects that could influence the overall climate.
And Feynman and her collaborators found that increased solar activity
could affect a certain climate pattern called the Northern Annular Mode,
leading to decreased rainfall in Africa.
So not only did Feynman help us understand
the colorful light shows in northern and southern skies;
she also made great leaps in understanding the star we live beside
and its connection to our lives.
Joan Feynman died in July of 2020,
but thanks to her decades of work and endless curiosity,
she left us with a new appreciation and understanding of our place in the natural world.
Thanks for watching this episode of SciShow Space!
And a special thanks to everyone who supports us—
whether it’s by joining our patron community or by
staying curious about the world. We’re here because of all of you.
And if you’d like to learn about how you can support SciShow,
you can find out more at patreon.com/SciShow.
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