Recent fndings lend strong support to the theory that a black hole lies at the Milky Way's center and many of the 100 billion other galaxies estimated to exist in the universe.

这个句子的表述是错误的。可做如下修改：

 Recent fndings lend strong support to the theory that a black hole lies at the centre of the Milky Way and many of the 100 billion other galaxies estimated to exist in the universe.

划线部分为and并列的二个名词词组，即银河系与1000亿个星系中的很多星系并列。然后作介词of的宾语。