Unless you can put all aspects of celestial phenomena under controlled conditions, observation alone does not cut it.
Astronomy does not follow the Scientific Method. Observe --> Interpret are the steps used in pseudosciences such as Astrology. It is not science.
as rama rightly points out, the scientific method does not require laboratories. they're useful for conducting experiments, but they're not fundamental to the method.
it's worth noting that the bedford level experiment is methodologically identical to the practice astronomy; the experiment does nothing more than record the brightness of an object. in this case the brightness observation is binary (did we collect any light from the bridge or didn't we?), but the method is fundamentally the same as observing stars. you didn't put the bedford level in a giant laboratory. nor the surface of the earth. surely you don't think those observations worthless, do you?
an old analogy, but i'm here, so fuck it: suppose i'm a taxonomist. i've studied the biology, physiology, and anatomy of all manner of plants and animals, and my field is obviously based on empirical laboratory and field research.
now let's suppose two odd things: 1) suppose that i've never seen a racoon before. never even heard of one. i have no idea that they exist. 2) suppose that someone could somehow take a photo of 100,000 different raccoons at a particular instant in time and give it to me on a flash drive. so now i'm a taxonomist who has never seen a raccoon before, and i have 100,000 images of different raccoons all at different stages of life and death. some are infants. some are dead and rotting. some are giving birth. some are eating. some are banging, jumping, running, fighting, hunting, scavenging, etc. you get the idea.
having never handled a raccoon before, i could nevertheless tell you a lot of true things about raccoons by relating what i see to the animals and plants that i
have studied. i could correctly classify them as mammals, describe their internal structure, fit them on the tree of life, and tell you a shitload else about their characteristics.
sure, there are plenty of questions that will be difficult to answer without getting my hands on a raccoon, but i'm still doing good science just by collecting photons.