The Observatory of Solar Dynamics has obtained a decade of images of our star. NASA summarized these observations, which correspond almost to a cycle of activity of the Sun, in an hour-long video.
Every 0.75 seconds, the Solar Dynamics Observatory (SDO) captures an image of the Sun. Thanks to satellite images, a decade of observations of the star could be summarized in a video of one hour, presented by NASA on June 24, 2020.
This observatory has been launched in February 2010, in order to understand the causes of the variability of solar activity. Since June 2010, the satellite placed in orbit around the Earth observes the star. SDO collected 425 million high resolution images of the star. This represents 20 million gigabytes of data. The following image, for example, was obtained from 151 shots taken by SDO over the decade.
On board, the observatory has several instruments on board, including the AIA (Atmospheric Imaging Assembly) camera: it takes photos of the Sun’s atmosphere in 10 different wavelengths, every 10 seconds. In this video, we see images that were taken at a wavelength of 17.1 nanometers. This corresponds to the extreme ultraviolet, making it possible to see the outermost atmospheric layer of the star, which is called the solar corona – this is what we can see during a total solar eclipse.
Almost a whole cycle of observations
With one photo per hour, the video sums up a decade of solar activity in 1 hour and 1 minute. The star precisely follows a cycle of activity 11 years old. The video thus makes it possible to see the increases and decreases of activities which correspond to a phase of this cycle, as well as notable events like transits of planets (this was the case with Mercury last November) or rashes. The video also contains some moments when the Sun is no longer fully visible, for example when the Moon or the Earth passes between the satellite and the Sun – we see for example a black sphere in front of the Sun at the 53rd minute. In 2016, the AIA instrument also had a temporary problem, resolved after a week.
The SDO mission made it possible to important discoveries on the Sun. During a year and a half after its commissioning, SDO saw around 200 solar flares, which helped to better understand the amounts of energy produced during these events. The observatory also saw comets passing in front of the Sun, providing data on the interactions of these objects with the star. The satellite was able to see almost an entire solar cycle, helping scientists anticipate the early signs of the decline of a cycle and the start of a new one.