The size of the star changes but not it's gravitational effect.
The gravitational effect was so slight he had not noticed it.
It was the first time that the gravitational effect of an earthquake had been observed.
We knew the dark matter was there because of its gravitational effects, but we've never seen it until now.
Since everything in the elevator is falling together, no gravitational effect can be observed.
In fact, it is believed that gravitational effects travel at exactly the speed of light.
On large scales however, space is bent by the gravitational effect of matter.
Or been moved out of the system quickly enough that the gravitational effect on the others was minimal.
While no one has touched dark matter, its gravitational effects are seen all the time.
After all, you don't know that this is primarily a gravitational effect here.