"and even the tiniest pebbles out there in space from cosmic dust."
no, this isnt a planet, but by finishing reading the sentence you would have learned that everything is effected by gravity. test it by throwing an apple in the air some time, if it does come back down, it will likely be due to gravity. which would lead one to believe that gravity applies to small things as well as large. and if you take physics in college, you will find that all matter applies gravitational attraction to all other matter, larger masses simply have more gravity than smaller masses.