My hand is a “nuller” when I want to look at an item near the sunset.
Lol. Think of the millions that could be saved if NASA employed your simple technique!
Nulling actually involves two separated telescopes working together as one. Each one gathers the light from a star in such a way that the 2 wavefronts are 180 degrees out of phase when combined and so thereby cancel each other out, making it possible to see the faint light of the planet or whatever that might be there.