Solar historical research with historical photographs –

Using historical data, Dr. Theodosios Chatzistergos from the MPS back into the past of our star. For this he received an important award. A press release from the Max Planck Institute for Solar System Research.

Source: Max Planck Institute for Solar System Research June 14, 2022.

dr Theodosios Chatzistergos. (Image: E. Asvestari)

June 14, 2022 – The Scientific Committee on Solar-Terrestrial Physics (SCOSTEP), a body of the International Science Council (ISC), has appointed Dr. Theodosios Chatzistergos from the Max Planck Institute for Solar System Research (MPS) received this year’s Distinguished Young Scientist Award. With this prize, the committee honors the young researcher’s contributions to the reconstruction of past activity and brightness fluctuations of the sun. dr Among other things, Chatzistergos has succeeded in making historical observations of so-called solar flares, particularly bright areas on the sun, more than 100 years old, usable for this purpose. Chatzistergos’ findings help to understand how much the Sun’s activity and brightness has varied in the past – and whether this affected Earth’s climate.

It takes more than a snapshot to understand the sun’s influence on Earth’s climate. Rather, it is necessary to look back as far as possible – both to the climate changes that have taken place on earth and to the changing activity of the sun. However, solar “historical research” of this kind is tricky: The decisive factor, the intensity of the solar radiation that hits outside the earth’s atmosphere, has only been able to be measured since 1978 with the help of satellites.

Thankfully, our star’s activity manifests itself in many ways. Radiation intensity fluctuations are caused by the constant appearance and disappearance of darker and lighter areas, called sunspots and sun flares, on the Sun’s visible surface. Both phenomena are driven by the Sun’s dynamic magnetic field and often occur when solar activity is high; in times of low activity they occur much less frequently. The dark sunspots can be seen from Earth with simple optical aids; astronomers have been recording their numbers since 1609. The sun flares, on the other hand, are harder to grab. The aim of Dr. Theodosios Chatzistergos.

Of stains and flares
Sunspots and flares often appear in close temporal and spatial proximity. In previous calculations, it was therefore often assumed that the number and area of ​​the solar flares can be deduced from historical records of sunspots. “However, the interplay of sunspots and solar flares does not run in perfect synchronization,” Chatzistergos points out. Images of the Sun looking at violet light of a specific wavelength provide much more accurate information about the occurrence of solar flares. It is emitted by ionized calcium ions in the particularly hot regions above the solar flares. Measurements of this type have existed since 1892, but not consistently from one and the same observatory.

From historical photographs of the sun like these, Theodosios Chatzistergos was able to create an archive of solar activity for the first time, based on observations of solar flares and covering the entire 20th century. The left picture was taken on June 11, 1935 in Kyoto (Japan), the right on January 1, 1969 in Catania (Italy). (Image: MPS (T. Chatzistergos))

Chatzistergos has succeeded in collecting and combining the various solar flare datasets from almost all regions of the world and thus making them usable as a long-term archive of solar activity for the first time. A treasure trove of data has been created that depicts the behavior of the sun over the entire 20th century. From data of this kind, the magnetic fields on the surface of the sun and from them the intensity fluctuations of the sun can be calculated. As the researcher has already shown, these calculations for the past decades agree well with the intensity fluctuations actually measured in space.

dr Theodosios Chatzistergos studied astronomy and astrophysics at the National and Kapodistrian University in Athens (Greece) and at Queen Mary University in London (England) and wrote his thesis on the moons and rings of Saturn. During his doctorate at the MPS, which he completed in 2017, he turned his attention to the sun and specifically to the reconstruction of its historical fluctuations in brightness. After a two-year research stay at the INAF Osservatorio Astronomico Roma (Italy), Dr. Chatzistergos back at the MPS since mid-2020.

SCOSTEP (Scientific Committee on Solar-Terrestrial Physics) is a body of the International Science Council, the world’s largest umbrella organization of national and international scientific associations. SCOSTEP brings together scientists from a wide range of disciplines who study the relationship between the sun and the earth. Every two years, the committee presents the SCOSTEP Distinguished Young Scientist Award to a young scientist for significant contributions to this research field.

SCOSTEP Distinguished Young Scientist Award Seminar
dr Theodosios Chatzistergos will report on his research results on Thursday, June 16 at 2 p.m. (CEST) as part of the SCOSTEP Distinguished Young Scientist Award Seminar.

Registration at is required to participate.

The lecture will be recorded and later made available at

#Solar #historical #research #historical #photographs #Raumfahrernet

About the author


Leave a Comment