Free Astronomy Magazine January-February 2019

16 JANUARY-FEBRUARY 2019 SPACE CHRONICLES ALMA maps Europa’s temperature by ALMAObservatory J upiter’s icy moon Europa has a chaotic surface terrain that is fractured and cracked, suggest- ing a long-standing history of geo- logic activity. A new series of four images of Eu- ropa taken with the Atacama Large Millimeter/submillimeter Array (ALMA) has helped astronomers cre- ate the first global thermal map of this cold satellite of Jupiter. The new images have a resolution of roughly 200 kilometers, sufficient to study the relationship between surface thermal variations and the moon’s major geologic features. The researchers compared the new ALMA observations of Europa to a thermal model based on observa- tions from the Galileo spacecraft. This comparison allowed them to analyze the temperature changes in the data and construct the first-ever global map of Europa’s thermal characteristics. The new data also re- vealed an enigmatic cold spot on Eu- ropa’s northern hemisphere. “These ALMA images are really in- teresting because they provide the first global map of Europa’s thermal A LMA image of Jupiter’s moon Europa. ALMA was able to map out thermal variations on its sur- face. Hubble image of Jupiter in the background. [ALMA (ESO/NAOJ/NRAO), S. Trumbo et al.; NRAO/AUI NSF, S. Dagnello; NASA/Hubble]