What does the area around the fan blades in the engine nacelle contain? I was intrigued to find this picture below. There was so much space around the engine. So what is inside of that extra space? Or is it just a hollow casing?



Image Source

Details about the picture as provided in the image source:


  [Last Year] A Southwest Airlines Co. flight landed safely Saturday
  morning following a major malfunction of one of its two engines during
  a flight across the Southeastern U.S.
  
  The Boeing Co. 737-700 was flying from New Orleans to Orlando early
  Saturday operating as flight 3472 when it suffered the failure,
  causing the jet to quickly divert to Pensacola International Airport
  in northern Florida at 9:40 a.m. CDT, according to a statement from
  the airline.
  
  A Southwest spokesman said its initial reports indicated no injuries
  were reported among the 99 passengers and five crew aboard.
Yes a bit of the engine called the nacelle is missing. This is an aerodynamic structure that slows the air down before it enters the compressor, the pointy bit in your photo. In the drawing underneath it states Inlet Cowl. It has some thickness, because it requires a certain nose shape for its function. Mainly a hollow casing indeed, but with a high tech shape.