A history of solar activity over millennia

Abstract

Here we review present knowledge of the long-term behaviour of solar activity on a multi-millennial timescale, as reconstructed using the indirect proxy method. The concept of solar activity is discussed along with an overview of the dedicated indices used to quantify different aspects of variable solar activity, with special emphasis on sunspot numbers. Over long timescales, quantitative information about past solar activity is historically obtained using a method based on indirect proxies, such as cosmogenic isotopes $$^{14}$$ 14 C and $$^{10}$$ 10 Be in natural stratified archives (e.g., tree rings or ice cores). We give a historical overview of the development of the proxy-based method for past solar-activity reconstruction over millennia, as well as a description of the modern state of the art. Special attention is paid to the verification and cross-calibration of reconstructions. It is argued that the method of cosmogenic isotopes makes a solid basis for studies of solar variability in the past on a long timescale (centuries to millennia) during the Holocene (the past $$\sim $$ ∼ 12 millennia). A separate section is devoted to reconstructions of extremely rare solar eruptive events in the past, based on both cosmogenic-proxy data in terrestrial and lunar natural archives, as well as statistics of sun-like stars. Finally, the main features of the long-term evolution of solar magnetic activity, including the statistics of grand minima and maxima occurrence, are summarized and their possible implications, especially for solar/stellar dynamo theory, are discussed.

Effects of Global Geomagnetic Field Variations Over the Past 100,000 Years on Cosmogenic Radionuclide Production Rates in the Earth's Atmosphere

“…The flux of GCR near Earth is modulated by solar magnetic activity on time scales ranging from hourly/daily to centennial/millennial, including periods of Grand solar minima, when the Sun is very quiet (see Usoskin, 2023, for a review). Although the GCR modulation process is complex (Potgieter, 2013), it is often parameterized for practical applications by a simple force‐field approximation (Caballero‐Lopez & Moraal, 2004; Usoskin et al., 2005), which includes a single modulation parameter ϕ in the units of rigidity and a prescribed local interstellar spectrum (LIS) of GCR.…”

Multiwavelength Campaign Observations of a Young Solar-type Star, EK Draconis. I. Discovery of Prominence Eruptions Associated with Superflares

“…The largest flare energy observed on our Sun is about 10 32 erg (e.g., Emslie et al 2012), while larger flares with the energy over 10 33 erg, referred to as "superflares," have never been reported in modern solar observations (e.g., Aulanier et al 2013). However, recent studies have identified multiple possible extreme solar energetic events with energies up to 10 34 erg that occurred in the past millennia using cosmogenic radionuclides ( 14 C, 10 Be, 36 Cl) recorded in tree rings and ice cores (e.g., Miyake et al 2019;Usoskin 2023). Furthermore, recent observations of solar-type (G-type main-sequence) stars have provided important insights into the rate of occurrence of superflares from the young solar-type stars and the analogs of the present-day Sun.…”

“…Such studies are critical for understanding the frequency and impact of these events on our civilization and its infrastructures. Thus, superflares on solar-type stars have been highlighted from the context of solar physics (e.g., Aulanier et al 2013;Shibata et al 2013;Cliver et al 2022), planetary science (e.g., Fujii et al 2018;Linsky 2019;Airapetian et al 2020), biochemistry (e.g., Kobayashi et al 2023), and historical and geophysical studies (e.g., Miyake et al 2012;Hayakawa et al 2017;Usoskin 2023).…”

Magnitude Estimates for the Carrington Flare in 1859 September: As Seen from the Original Records

“…These analyses are particularly important because the powerful solar flares observed in WL are occasionally accompanied by major interplanetary coronal mass ejections (ICMEs) and solar energetic particles (SEPs), which can have major impacts on space weather and modern technological infrastructure (Usoskin 2023;Hudson 2021;Temmer 2021;Cliver et al 2022).…”