Agenzia Spaziale Italiana

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SCORE under the Sun

The Italian instrument, launched on 14 September, has obtained the first images of helium in the Sun's corona


For the first time, a telescope has trained its eyes on the Sun and managed to photograph the helium emissions that burst from the corona of our star (in the photo on the left). The credit for this achievement goes to SCORE, (Sounding-rocket Coronagraphic Experiment), the Italian instrument for studying the Sun's external atmosphere, which was successfully launched (after various postponements due to technical and meteorological problems) on board a NASA rocket from the White Sands Missile Range base in New Mexico on 14 September. The mission, part of the HERSCHEL programme (HElium Resonance Scattering in the Corona and HELiosphere, homonymous with the ESA infrared telescope), is the fruit of collaboration between ASI and NASA and was developed in Italy by research groups from the INAF-Astronomical Observatory and ALTEC in Turin, and the Universities of Florence and Pavia.


SCORE was designed to obtain images of the coronal emission in the visible, ultraviolet and extreme ultraviolet wavelengths. Initial analyses of the data have confirmed the complete scientific success of the experiment and as expected, the first image of the helium emission in the solar corona has been obtained. Hydrogen is the most abundant element in the Sun and helium is the second and this result constitutes the first measurement of the abundance of helium in the corona; information of great importance for understanding solar wind formation.


The structure of the corona differs considerably depending on whether SCORE observes the helium or hydrogen emissions. This result indicates that there are considerable variations in the composition of the solar atmosphere.  From a technological point of view, the experiment has demonstrated that one telescope can observe emissions from the external corona in wavelengths from visible to the extreme UV, thanks to the use of multilayer-coated optics.


The success of this new coronagraph technology is important because it is the same that will be used by METIS (Multi Element Telescope for Imaging and Spectroscopy). This is the instrument chosen by the European Space Agency as the scientific payload on the Solar Orbiter, the space probe that will first enter Mercury's orbit and then deviate more than 30 degrees from the solar equatorial plane to observe the still unexplored solar poles.


The solar corona has become the subject of particular interest for space agencies worldwide, because it is the ring of conjunction between the Sun and the heliosphere. Within the heliosphere and immersed in the solar wind, the planetary magnetospheres are continuously perturbed by the Sun's magnetic and eruptive activity.  The corona is therefore the key to understanding the phenomena that control the effects of the Sun on climate change.