To observe our closest star – Sun, different types of telescopes can be used. Generally, solar telescopes have the same construction design as night-time telescopes, but with some improvements.
In most cases, solar telescopes are refractors with a smaller aperture. Personal solar refractors usually have between 40 to 60 mm aperture.
When observing the Sun, the light is magnified so much that it can damage your eyes. To ensure safety, the user needs to place a proper solar filter at the front of the telescope. Special built-in interface filters allow direct aiming at the Sun.
With a protected telescope, the Sun can be observed in different wavelengths:
This type of observation allows the user to observe the Solar photosphere and sunspots. An observation with a white light solar filter is the cheapest solar observation – any telescope can be turned into a solar telescope.
Sun in white ligh (right) and in H- alpha (left) (Available from https://www.skyandtelescope.com/observing/guide-to-observing-the-sun-in-h-alpha092321050923/. [accessed 29 Oct 2019])
This observation is done with an HA telescope. It allows observation of the granulation on the Solar chromosphere, spicules, fibrils, Ellerman bombs, flares. An H-alpha solar telescope allows the user to see dynamic features. Only a very narrow band of light at 656 nm wavelengths – hydrogen spectrum (red-orange light) can pass through the filter, while white and IR light cannot.
Hydrohen-alpha filter (Available from https://www.skyandtelescope.com/observing/guide-to-observing-the-sun-in-h-alpha092321050923/. [accessed 29 Oct 2019])
This observation is used to study the wavelength of 393 nm, which is on the edge of the visual spectrum. Calcium K telescopes are mostly used in astrophotography.
Calcium K-line filter (Available from https://www.skyandtelescope.com/astronomy-news/how-to-look-at-the-sun/. [accessed 29 Oct 2019])