The Horsehead Nebula, or Barnard 33, appears here in infrared observations released in 2013. Infrared light can penetrate dusty material that obscures parts of the nebula in visible light. This entry shows why changing wavelength can change the apparent character of one object.
Look at the folded edges rather than only the horse-like silhouette. The colours display infrared data; they are not what human eyes would see unaided. A different-looking portrait need not mean the nebula itself has suddenly changed.
Source/image: NASA, ESA, and the Hubble Heritage Team (AURA/STScI) · CC BY 4.0. Resized; colours retained.