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This review provides an introduction to the generation and evolution of the Sun's magnetic field, summarising both observational evidence and theoretical models. The eleven year solar cycle, which is well known from a variety of observed…
Recent observations of Krucker & Benz (1998) give strong support to Parker's hypothesis (Parker 1988) that small scale dissipative events make the main contribution to quiet Sun coronal heating. They also showed that these small scale…
The solar cycle periodically reshapes the magnetic structure and radiative output of the Sun and determines its impact on the heliosphere roughly every 11 years. Besides this main periodicity, it shows century-long variations (including…
North-south asymmetry of sunspot activity resulted in an asynchronous reversal of the Sun's polar fields in the current cycle. The asymmetry is also observed in the formation of polar coronal holes. A stable coronal hole was first formed at…
The solar minima between solar cycles 22-23, 23-24 and 24-25 are the best observed minima on record. In situ solar wind and interplanetary magnetic field measurements by the WIND and ACE spacecraft at L1 with one-hour cadence are explored…
Many questions have to be answered before understanding the relationship between the emerging magnetic flux through the solar surface and the extreme geoeffective events. Which threshold determines the onset of the eruption? What is the…
Recently, a significant carbon-14 enhancement in the year 994 in tree rings has been found, suggesting an extremely large cosmic ray flux event during a short period. The origin of this particular cosmic ray event has not been confirmed,…
We present results of a dual eclipse expedition to observe the solar corona from two sites during the annular solar eclipse of 2023 October 14, using a novel coronagraph designed to be accessible for amateurs and students to build and…
A statistical survey of 26 major electron events during the period 2002 February through the end of solar cycle 23 is presented. We have obtained electron solar onset times and the peak flux spectra for each event by fitting to a powerlaw…
We have studied solar activity and space weather conditions during multiple planetary conjunction periods ( MPC) as observed from Earth during the years 1850-2000 AD. Significant decreases in sunspot activity and solar 10.7 cm radio flux…
Solar activity is studied using a cluster analysis of the time-fluctuations of sunspot number. In the historic period (1850-1932) the cluster exponent was approximately equal to 0.37 (strong clustering) for the high activity components of…
Coronal mass ejections (CMEs) were discovered in the early 1970s when space-borne coronagraphs revealed that eruptions of plasma are ejected from the Sun. Today, it is known that the Sun produces eruptive flares, filament eruptions, coronal…
Solar mini-dimmings can be detect in the Extreme Ultra-Violet coro- nal eruptions. Here, sequences of 171 A images taken by Solar Dynamic Observa- tory/Atmospheric Imaging Assembaly on 13 June 2010 are used. In this special day, both of…
We study the interaction of three solar wind structures, two stream interaction regions and one interplanetary coronal mass ejection, with Mars' plasma environment during 20-27 November 2007. This period corresponds to the solar minimum…
We continue the investigation of a CME-driven coronal dimming from December 14 2006 using unique high resolution imaging of the chromosphere and corona from the Hinode spacecraft. Over the course of the dimming event we observe the dynamic…
The Maunder Minimum (1645-1715) is currently considered the only grand minimum within telescopic sunspot observations since 1610. During this epoch, the Sun was extremely quiet and unusually free from sunspots. However, despite reduced…
We reconsider the description of a solar eclipse in the Coptic ostracon in the Egyptian museum, Turin, confirming its identification with the solar eclipse of 10 march 601. This provides one of very few fixed dates in Coptic chronology. We…
We study the solar energetic particle (SEP) event associated with the 2012 July 23 extreme solar storm, for which STEREO and the spacecraft at L1 provide multi-point remote sensing and in situ observations. The extreme solar storm, with a…
The elemental composition in the coronae of low-activity solar-like stars appears to be related to fundamental stellar properties such as rotation, surface gravity, and spectral type. Here we use full-Sun observations from the Solar…
The cluster formed by active regions (ARs) NOAA 11121 and 11123, approximately located on the solar central meridian on 11 November 2010, is of great scientific interest. This complex was the site of violent flux emergence and the source of…