A P212 aircraft reported seeing orange and yellow lights at 5,000 FT MSL at roughly the HOP050035.

At roughly 5:40PM CST, a P212 small air carrier aircraft's pilot asked us, Fort Campbell ATC, if we had any military aircraft operating at his 12 o'clock in 15 miles (roughly the HOP050035). There were no primary or secondary aircraft appearing on radar ahead of him and the pilot was informed of this. When asked why he inquired, the pilot reported orange/yellow lights that glowed brightly. When asked whether these lights dropped down like a flare, or whether they stayed at a constant altitude, the pilot responded that the lights stayed at roughly 5,000 ft. A few minutes later the pilot reported that he no longer saw the object.