Logo Sunspot Sunspots



It has conducted a thorough and detailed study of these techniques with the purpose of processing images of the solar photosphere. The photosphere is the area from which is emitted most of the visible light from the sun and it is there where you can see darker areas called sunspots. Throughout the solar cycle, the sun undergoes changes in its electromagnetic field causing these stains which are studied in this project.

The importance of research of the Sun and the activity of sunspots is that they are directly responsible for the eruptions of material that occurs at the solar surface. When these materials reach the Earth, producing a geomagnetic storm, the most visible impact is the aurora borealis. However, we also produce other negative effects such as damage to satellites and even overhead and power.

After conducting a study of the photosphere and see different images to draw conclusions about the morphology of sunspots, has developed a procedure based on computer vision techniques described above, with the aim of identifying and estimating the area sunspots in the photosphere.


Sunspots are dark areas in the solar photosphere, the area from which emits most of the visible light from the sun.

A typical sunspot consists of a central dark umbra surrounded by a known region called penumbra clearer. Both areas appear darker because its temperature is cooler than the average temperature of the photosphere. Penumbra is formed by the structure of light and dark filaments that extend radially from the umbra.



Sunspots appear, grow, change size and appearance and disappear. The duration is approximately one or two solar rotations, ie for one or two months although the half-life is two weeks. Typically, sunspots, usually appear in pairs. The life cycle can be summed up in that first there was a brilliant call pore formation, the next day and there is a small stain and a few degrees of it, the twin pore appears and another spot, a few days, the two spots have the appearance umbra and penumbra characteristic. Together these two may appear smaller. Between the two major spots, there is a magnetic field with an intensity between 0.2 and 0.4 T (Tesla).

The origin of the creation of sunspots is still under investigation, yet it is quite clear that sunspots are the visible aspect of the magnetic flux tube that forms beneath the photosphere. In these tubes the pressure and density are lower and therefore rise and cool. When the tube force breaks the surface of the photosphere when the pore is that, as mentioned before, is a region brighter than the rest, and is there when the cycle of sunspots.

The opposite polarity is observed in the pairs of spots is because one of them the magnetic field is emerging while the other is re-introduced into the interior.

Bipolaridad de las manchas solares

Bipolarity of sunspots

All sunspots in both hemispheres at latitudes ranging from 5 º to 40 º. Solar activity occurs in cycles of about eleven years. The point of high solar activity during this cycle is known as the solar maximum, the point of activity and lower the solar minimum. At the beginning of a cycle, sunspots tend to appear in the higher latitudes (40 º) and as the cycle approaches the maximum spots appear more often and increasingly less latitude (near equator) until it reaches the maximum. While this is the first spots appear in the next cycle at a latitude of about 40 degrees. This is called the law of Spörer.

Representation for each cycle of the spotted area of the surface depending on latitude, provides a diagram in the shape of a butterfly called Maunder diagram.

Butterfly diagram

Butterfly diagram

This chart shows the position of sunspots in the years 1870 and 1995. Note the center, from left to right, is the ecuador del Sol, and the stains will occur in North and South.

The study of sunspots is that, from them, you can learn about solar activity and how this activity affects the earth.

In this application have participated:

  • Trabajo Fin de Máster, Máster Universitario en Ingeniería Informática, Escuela Politécnica, Víctor Castiñeira García, directores: Pablo García y Jose Manuel Vaquero, "Sunspotweb: Analyzing sunspots with a web application", Febrero 2013. Memoria  Download , Presentación  Download

  • Proyecto de Fin de Carrera, I.I., Escuela Politécnica, Nuria Carrasco Gallardo, directores: Andrés Caro y Maria Luisa Durán, "Estimación automática del área de manchas solares", Septiembre 2008. Memoria  Download


Image gallery

Below is a gallery of images used as examples of the application.

To download the images (which previously had to be uncompressed to estimate automatically), click here  Download .



{tab-requisitos=Web Application}

This is a new application.

We recommend using the Firefox and Chrome browsers.

{tab-requisitos=Desktop application}

Listed below are the files and packages that need to be installed before running the application:

- JVM (Java Virtual Machine). (Download here).


  • .NET Framework Redistributable Package version 2.0 (x86). (Download here)
  • .NET Framework Software Development Kit (SDK) version 2.0. (Download here)


{tab-aplicacion=Web Application}

This is a new application.

The web application is in the link below, sunspotweb.unex.es



{tab-aplicacion=Desktop application}

Files needed

The following additional files that the user must save to disk in your system:

- File. RAR with solar images (which previously had to be uncompressed to estimate automatically). (  Download )


Make sure you have the packages and files (mentioned above) installed on your system before you start the application.

Click on the link below to run the application  Download and then select "Open with: Java (TM) Web Start Launcher".



{tab-ayuda=Manual web application user}

This is a new application.

It is available for a user manual for this application,  Download

{tab-ayuda=Application Help Desk}

Main view of the Application

The top part of the application provides a menu bar with diferents options. Also provides a tools menu with severals bottons that makes easier to use a few menu options.

Provides the following menus and submenus:

Menu Archivo 001

File Menu (up)

This menu allows the opening and closing images of the application.

Open Image (up)

The opening option allows us to select an image from your PC via a file selector (filechooser). We can navigate through the different directories on our computer and further provides a preview of the images you select.

By default, the first time we ask to open an image, the application looks for it in the folder "solar images" in the directory where you installed the application.

It also has a button with the same functionality in the toolbar.

Once the image is opened, the main screen of the application is show like this.

Exit (up)

This option allows the user to exit the application in time. When selected, the system prompts the user if it is sure it wants to quit the application. Otherwise you can continue working with the application.

It also has a button with the same functionality in the toolbar.

Edit Menu (up)

This menu allows the user the option to run the process for calculating the area of sunspots from an image previously opened.

Calculate sunspot area (up)

When you select this option runs the process for calculating the area of sunspots in a solar image previously open. Once executed this process, the application opens another window in which we show the results obtained.

As can be seen on the right side shows the solar image which with each of spots or regions perfectly identified. On the left side of the screen are the results obtained. This part is divided into two zones:

  • Top: where are the specifics of each spot, such as:
    • Coordinates when it is in the image (taking into account that the coordinate 0.0 is in the upper left corner of the image).
    • Total area of the stain (area umbra + penumbra area).
    • Angulo blueprints of the center of the sunspot, expressed in degrees, minutes and seconds.
  • Bottom: where are the image data, such as:
    • Solar total area stained.
    • Coordinates of the solar center (taking into account that the coordinate 0.0 is in the upper left corner of the image).
    • Image size.
    • Name of the input image.
    • Name of the output image: will be automatically saved in the same directory where the original image with the same name but ending in "modif.".

Also, the results can be saved by pressing the button Export Results. When pressed about it, we see a directory browser that allows us to save the results anywhere on your PC. The default is always open "My Documents".

The results are always saved in plain text files (.txt). Below is an example.

In the event that the results have been stored properly and if not, the application will inform us about it by a message.

You may also be the situation of the user to enter a different extension to txt. In this case the application of this information.




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