Joan Feyman : Unveiling the secret of the Northern Lights

July 22 will be the occasion to celebrate the death of a great astrophysicist, whose many years of research led her to the study of particles, the solar wind field, the Sun-Earth relationship, the physics of the magnetosphere, and the origins of the aurora borealis.

Space has always intrigued humanity. The moon inspires poets, the stars guide ships, its sheer immensity questions us on the presence of life. The northern lights also have their share of stories. In ancient times, there was no way to understand their origin; these "northern lights" were sometimes mistaken for snakes or colored dragons that roamed the sky. It was not until the 17th century that this phenomena was studied scientifically. Many people worked on this mystery before it was solved for good.


Image: The Northern Lights can be seen in the night sky

One of them is the famous American astrophysicist Joan Feyman born on March 31, 1927. One night, her brother took her to see the Northern Lights over a golf course near their home, the catalyst to a lifelong interest in the  phenomenon. Years later, Joan then goes on to earn  her doctorate in 1958 at Syracuse University. She spent many years studying different physical phenomena, notably at Columbia University, where she did research on the earth's magnetosphere. Later in California, at the Jet Propulsion Laboratory, she (finally) had the opportunity to study her passion and trigger to her obsession, the aurora borealis.

Aurora borealis, the journey of a particle


Auroras are called aurora borealis in the Northern Hemisphere and auroras australis in the Southern Hemisphere. It is an atmospheric light phenomenon characterized by veils, colored mainly green, in the night sky. When the Sun erupts, it rejects particles that are disseminated in the universe. Some of these particles go in the direction of the magnetic poles; indeed the earth is surrounded by a magnetic field, already present 3.45 billion years ago (which means that all species living before us, from dinosaurs to the first tetrapods emerging from the water, and even older species, could already observe these structures veiled in the sky).


When these solar particles are captured by the earth’s magnetic field, they collide with the atoms of the atmosphere. The particles electrically charge these atoms, which cannot naturally remain in this state. By ejecting the excess electrons, the atoms release some energy, and it is this energy that gives the aurora its color. So,, the aurora borealis are in fact due to particles of the Sun, but it is the photons of the atmosphere that we observe directly.


Image: the particles ejected by the Sun end up in the upper atmosphere at the magnetic poles

Joan Feyman and the advances


Image: Joan Feyman, American astrophysicist

Joan Feyman has discovered many phenomena during her lifetime. In addition to her research on the aurora borealis, she also studied the Sun-Earth relationship, the physics of the magnetosphere, and created a model that predicts the number of high-energy particles that can hit a spacecraft over its lifetime. She also helped make it easier for women to gain recognition in the research world, lobbying for women to be able to present papers and chair sessions at national scientific conferences. Joan Feyman passed away on July 22, 2020 at the age of 93.