We may find, say, that's a mercury lamp. This is how astronomers figure out what things are made of. The atmospheres of planets, stars, gas clouds out in space, etc. A hot, dense object will create a continuous spectrum following Wien's Law. Solid objects behave as blackbodies, they don't generate light by electron transitions, they use a different process.
Stars are hot, dense objects which emit a continuous spectrum of light from their surface.
See figure 3.14 on page 108 . Observer looking directly at the star. Will see a continuous spectrum. Consider an observer looking through a gas cloud towards star. Some of the light passing through the cloud will have just the right energy to be absorbed by an electron changing orbits.