Waves from the sun: to the 100th anniversary of V. A. Troitskaya’s birth

It has been one hundred years since the birth of the outstanding scientist Professor V.A. Troitskaya. Her remarkable achievements in solar-terrestrial physics are widely known. For many years, Valeria Alekseevna was the President of the International Association of Geomagnetism and Aeronomy. This article deals with only one aspect of the multifaceted creative activity of V.A. Troitskaya. It relates to the problem of sources of ultra-low frequency (ULF) electromagnetic oscillations and waves outside Earth’s magnetosphere. We were fortunate to work under the leadership of V.A. Troitskaya on this problem. In this paper, we briefly describe the history from the emergence of the idea of the extramagnetospheric origin of dayside permanent ULF oscillations in the late 1960s to the modern quest made by ground and satellite means for ULF waves excited by solar surface oscillations propagating in the interplanetary medium and reaching Earth.