The solar variability is investigated nowadays using a large spectrum of approaches, both from ground and in space. The current solar space-bound instruments include the SOHO (Solar and Heliospheric Observatory), STEREO (Solar-Terrestrial Relations Observatory), Hinode and SDO (Solar Dynamics Observatory). On the ground however, there is a much larger number of solar observatories, as well as numerous initiatives on the amateur observations side. The professional observatories include instruments ranging from about 10 cm in diameter (actual resolution on the Sun of around 800 kilometers) to 1.5 meters (actual resolution of 60 kilometers). Some instruments are historic ones and are operated mostly for public outreach or occasional science. Others are used daily for science data like Wolf number determination in order to maintain the solar activity statistics as it was started back 150 years ago. There are also the high-technology instruments, like the Big Bear Solar observatory in the US (1.6 meters in diameter), and the Swedish 1-meter telescope in the Canary Islands, used mainly for cutting-edge solar science of small-scale structures in the chromosphere or photosphere of the Sun. Although extremely powerful, the focus of these observatories is mainly on specific fundamental solar phenomena and they are less adapted for operational tasks. Planned instruments or already under construction go as large as 4 meters for future very high-resolution studies of the solar surface. All these instruments however, are dedicated for low-field-of-view image acquisition, and continuous study of the entire surface of the Sun is impossible. This is where smaller size observatories can play a role as they allow for full-disc observations or the occasional higher resolution of some larger phenomena like sunspots, solar granulation evolution and flares.

The main advantage of medium sized observatories is not related to the size of the telescope used but indeed to their relatively large number that makes them a virtual worldwide network qualified for almost continuous observations of the Sun and its short-lived explosive events that can be observed far ahead of the larger observatories. Coupled with the space-bound observatories, the data from the ground instruments (both large and medium sized) give us a continuous view of the activity of our star and allows for better predictions especially in the case of eruptive phenomena. These phenomena are mostly studied, at ground level, in white light (400-700 nm), H-alpha light (656.28 nm) or Calcium (K-line especially, at 393.4 nm). All these filters show different layers in the solar atmosphere, with the K-line filter showing the solar granulation up to around 100 km from the photosphere level and also the inter-granular bright spots that lie some 200 km below it, while the H-alpha line filters allowing the viewing of the inner chromosphere (up to about 2500 km from the photosphere).

The medium resolution capabilities of our observatory at the ISS allows the investigation of spatial scales on the order of 300 kilometers at the solar surface; such performance is enough to produce good images and measurements of solar phenomena like Ellerman bombs (size of 2x1 arcseconds, or about 1500 kilometers on the Sun), spiculae (size of about 0.5 to 0.6 arcseconds, or about 500 km in diameter), or sunspot penumbral waves evolution (structures of 1 to 3 arcseconds, or 700 to 2000 kilometers). The science that can be done using ground-based instruments is complex and, besides the regular-basis sunspot monitoring which itself is a highly important reason for a solar observatory to exist, additional scientific tasks can be performed with medium-sized instruments. They are performed nowadays at large and small sized observatories around the World, with different resolutions and frequency, and include fast-evolving phenomena like: