Very long baseline interferometry (VLBI) can be used to measure deflection of light by the sun with very high accuracy, which allows the testing of a prediction of general relativity.
On one of the fundamental consequences of general relativity: the deflection of light by gravity
The connection between one of the fundamental principles of general relativity and the gravitational deflection of light
Historical sketch of the derivation of general relativity’s prediction of gravitational lenses and subsequent astronomical observations
One of the fundamental effects predicted by general relativity, and some of its astronomical applications