ALMA’s solar debut

ALMA, 17 JANUARY 2017

ALMA has begun imaging the Sun for the first time, observing our star’s chromosphere in millimetre-wavelength light to produce these amazing images, the highlight being a giant, dark sunspot (shown inset) that is almost twice the diameter of Earth. Sunspots are temporary features on the solar surface, occurring where the magnetic field is particularly concentrated – this causes a drop in temperature that makes the area appear darker.