>Imagine dark matter had been proposed in 1900: the deviations in Mercury's orbit (from Newton's model of gravity) could have been attributed to dark matter. No

>Imagine dark matter had been proposed in 1900: the deviations in Mercury's orbit (from Newton's model of gravity) could have been attributed to dark matter. No need for general relativity... You should have a look [here](https://io9.gizmodo.com/the-200-year-old-mystery-of-mercurys-orbit-solved-1458642219 https://io9.gizmodo.com/the-200-year-old-mystery-of-mercurys...): TLDR: they looked for a 'Vulcain' planet which could cause Mercury's precession, but they didn't found one. And for the dark matter, you're right that both aspects should be researched, and both ARE researched but dark matter currently fits better the experimental data as already said. Of course until we know exactly what is dark matter, there will be room for other theories..