Hannes Alfvén was a Swedish physicist born on May 30, 1908, and he is best known for his work in plasma physics. He developed the theory of magnetohydrodynamics, which studies the behavior of electrically conducting fluids in magnetic fields. His contributions significantly advanced our understanding of space physics and astrophysics. In 1970, Alfvén was awarded the Nobel Prize in Physics for his groundbreaking research. He also made important contributions to the study of cosmic rays and the solar wind, helping to explain various phenomena in the universe. Alfvén passed away on April 2, 1995, leaving a lasting legacy in the field of physics.