Jean Focas facts for kids

Quick facts for kids Jean-Henri Focas
Born	20 July 1909 Corfu, Greece
Died	3 January 1969(1969-01-03) (aged 59) Athens, Greece
Nationality	Greek, French
Alma mater	University of Paris
Known for	Focas (lunar crater)
Children	Errikos Fokas
Scientific career
Fields	Astronomy Physics Celestial Cartography
Institutions	National Observatory of Athens Pic du Midi Meudon Great Refractor
Doctoral advisors	Audouin Dollfus André-Louis Danjon

Jean-Henri Focas (Greek: Ιωάννης Ε. Φωκάς; 20 July 1909 – 3 January 1969) was a talented Greek-French astronomer. He was also a painter, designer, illustrator, astrophysicist, and photographer who could speak five languages! Jean-Henri was known for studying planets and moons from big observatories in Athens and France.

He created the most detailed map of Mars ever made by someone just looking at the planet. He also invented special cameras to photograph things in space. In 1961, he wrote an important book about studying Mars, which became a classic. Because of his amazing work, a crater on the Moon and a crater on Mars are named after him.

Jean-Henri's Early Life and Learning

Jean-Henri Focas was born on the Greek island of Corfu. From a young age, he loved astronomy. When he was in high school, he often visited a small observatory on Kogevina Hill in Corfu. This observatory was built by a famous lunar photographer named Félix Chemla Lamèch.

Félix was very impressed by Jean-Henri's artistic skills. Jean-Henri was great at painting and drawing incredibly detailed pictures of planets. So, Félix took him on as an apprentice. This meant Jean-Henri learned about astronomy firsthand, including how to make complex observations of space.

Jean-Henri's impressive abilities caught the eye of another Greek astronomer, Stavros Plakidis. Plakidis recommended the young astronomer to the head of the National Observatory of Athens, Demetrios Eginitis. Around 1931, Focas became an assistant at the observatory. He started writing papers that were published all over the world. At just 18 years old, Jean Focas became the general secretary of the Astronomical Society of Greece, which Félix had started in Corfu.

Working at the Observatory

Jean-Henri spent a big part of his life at the National Observatory of Athens. He learned a lot from Plakidis, Eginitis, and other astronomers there. He kept writing papers and continued his detailed artistic drawings of things in our Solar System. These included sunspots, variable stars, comets, and especially the surfaces of different planets. In 1937, he wrote an article called Observations of Saturn's Rings.

While at the Athens observatory, he even designed complex tools. One was a camera made from plywood and black velvet. It was used to take pictures through a telescope.

Challenges and Discoveries

In the late 1930s, the astronomical station was moved to Penteli. But sadly, when the Nazis invaded Greece during World War II, most of the observatory's instruments were taken apart and hidden to keep them safe.

After the war, Focas continued his research. In 1948, he wrote La Planète Saturne (The Planet Saturn). By the early 1950s, he was doing advanced research in astrophysics. He wrote a paper about the light from the Moon during a total lunar eclipse in 1953. This paper was so important that it was presented to the French Academy of Sciences.

A year later, in 1954, he traveled to the Pyrenees Mountains in Southern France. There, he used a new 60 cm telescope at the Pic du Midi Observatory to study space. About ten years later, NASA used the same facility to get ready for the Apollo 11 Moon landing! When he returned to Athens, he brought back new ways of observing and photographing space that he learned in France.

International Collaboration and Legacy

By this time, Focas traveled to France once a year. He worked at the Observatory of Meudon and visited other observatories across France. In 1961, he earned his Ph.D. from the University of Paris. His main project was a detailed study of the seasonal changes on Mars.

In early 1964, he visited the Lowell Observatory in Arizona, USA. He worked with the International Astronomical Union to help set up two centers for planetary photography. One was at Lowell Observatory and the other at Meudon.

That same year, Stavros Plakidis retired. Jean-Henri's son, Errikos, said that his father had a disagreement with the leaders at the National Observatory of Athens. So, Focas moved to France permanently. During this time, he made over a thousand measurements of Jupiter. This work helped him understand how cloud formations in Jupiter's upper atmosphere changed over time.

Throughout his life, Focas became an expert at using telescopes, micrometers (for tiny measurements), and equipment for measuring light from stars and taking pictures of space. He built on the work of earlier astronomers like Evgenios Antoniadis and Bernard Lyot.

Sadly, Jean-Henri Focas died too soon at age 59 on January 3, 1969, from a heart attack while visiting Greece for the holidays. His life story was written by one of his mentors, French astronomer Audouin Dollfus.

As a tribute to his contributions, two craters are named after him:

• The Focas lunar crater on the southern part of the Moon, which is about 22 kilometers wide.
• The Focas Martian crater on the northern part of Mars, which is about 76.5 kilometers wide.

Jean-Henri Focas's Books and Articles

See also

In Spanish: Jean Focas para niños

• Phokas (Byzantine family)