The VIIRS active fire global map detected 552 fires in the Ukraine on April 09, 2018 which is the day this Suomi NPP satellite image was taken. The Visible Infrared Imaging Radiometer Suite (VIIRS) sensor was launched aboard the Suomi National Polar-orbiting Partnership (NPP) satellite and has the capability of sensing heat signatures on land that are higher than those nearby and are indicative of fires. For April 9, 2018, VIIRS was able to detect 552 separate hotspots within the Ukrainian borders. These fires are most likely agricultural fires that have been set to clear fields for the new planting season, but some of these fires could also be wildfires that may have been started by lightning or could be fires set intentionally that got out of control. Note that surrounding countries do not have nearly the same number of fires, that is probably due to the fact that these fires were set deliberately and the surrounding countries are not using the same agricultural methods at this time.
NASA image courtesy Jeff Schmaltz LANCE/EOSDIS MODIS Rapid Response Team, GSFC. Caption by Lynn Jenner with information from the VIIRS active fire global map.
Suomi NPP is managed by NASA and NOAA.