If universe is expanding but mass of sun and planets is not then shouldn't gravity be reduced due to space-time and mass relation?

Answer 1

The answer is that the expansion of the universe is only noticeable over distances of hundreds of millions of light years or more. Over the much smaller distances found within galaxies and planetary systems its effects are negligible.

Answer 2

Yes. If, The Universe is expanding. E = -GmM/r is gravitational energy, matter and energy are part of the Universe , are they "expanding"?

If , it Is only the empty space that is "expanding"? How can that be the meaning of an Expanding Universe? Further, Is space empty? If space is not empty then expanding space means creating new matter as the Universe expands. Something form nothing.

The answer is the Universe is not Expanding.

Answer 3

While the Universe is expanding, the mass of the Sun and planets remains constant. Gravity depends on the mass of an object and the distance between objects. Although the distance between galaxies is increasing due to the expansion of the Universe, the gravitational force between the Sun, planets, and other celestial bodies remains largely unaffected because the local structure of spacetime where these objects are located is not significantly impacted by the overall expansion of the Universe.