observably

To a detectable degree, sufficient to be observed.

As the planet orbits the star, it causes a wobble in the star's motion, which can be detected as a small but observably large Doppler effect.

In an observable manner.

From the point of view of earth-based observatories, the effect of the planet's orbit around the star is that the star observably wobbles.

Indicates that the proposition can be verified by observation.

Observably, the star wobbles.