Does the Sun's gravity pull or push?

Answer 1

Straight Answer:

The force of gravity is attractive. It is only attractive.

It has been a matter of deep wonderment by some of the worlds' greatest scientists as to why one only sees gravity as an attractive force.

Complex Answer:

The above answer really responds to Newton's form of gravity. The answer is 100% correct, even if one interprets gravity in the sense of General Relativity.

However, if one is willing to entertain various complex and possibly unlikely scenarios, one can come up with different versions of gravity. Not all of these can be correct and maybe none are.

1. Half a century ago, antimatter was discovered. For example, a positron is an "anti-electron," identical to a positive electron and would attract a negative electron. Some people wondered if antimatter would also have the opposite of the normal gravitational force and repel normal mater.

2. After the first Voyager satellites were launched and went outside of the solar system, it was noticed that they were not leaving as fast as expected. After years of research trying to understand why they were going slower than expected, it was conjectured that Newtons law of gravity, might not be exactly correct for long distances, i.e. for distances of billions of kilometers. They just could not come up with any other explanation.

3. When Einstein first published his theory of General Relativity, the field equations had a term in them which was called the Cosmological Constant. In the first decades of the 20th century it was thought we lived in a static universe and something had to be present in the law of gravity to keep all the stars from falling in to one giant clump. That thing was the Cosmological Constant. Later, once it was established that we live in an expanding universe, Einstein characterized the first version of the theory, with the Cosmological Constant, as "the biggest mistake of my life."

4. A century after Einstein's biggest mistake, it has been discovered that the universe is accelerating, no just moving apart. Current theories now put the Cosmological Constant back into General Relativity to explain the acceleration.

5. Dark energy is the biggest unsolved mystery in science and has a tremendous implication on what is the correct law of gravity, the future of the universe and all manner of other fundamental questions.

Still, in all of the above, except antimatter, gravity was still attractive.