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Sun4All experiment

The project Sun4All aims to promote science in general and astronomy in particular. The project is based on an asset of over 30000 images of the Sun (spectroheliograms) that are kept at the Astronomical Observatory of the University of Coimbra, as result of a work of over 80 years of daily solar observations, started in 1926. This is a Sun observation collection of great scientific value.

The project aims at involving all citizens in the analysis and counting of the sunspots is a very important aspect of the study of the phenomena occurring on the surface of Sun and to understand the solar activity and solar cycle. On the other hand studying the sunspots, besides being interesting itself, presents an important tool to understand much of what happens on the Earth climate.


In this application you’ll find an image of the sun - a spectroheliogram - dated with the day when was taken. The purpose of this application is to count sunspots and sunspots groups. To do that, we provide you with tools to manipulate the image and to do the counting.


This is a project promoted by researchers at the Department of Mathematics of the University of Coimbra and the Astronomical Observatory of the University of Coimbra. The application was developed by the team of SOCIENTIZE project.

Sun4All iconic image