This is an interesting question. We know a lot about the Universe, but not enough to answer all the questions about it. In our Solar System the Sun, which is a star, is the biggest object. We do not know any planet bigger than the Sun, but we know that far away there are other stars bigger than our Sun and there are some smaller than it.

For instance, some astronomers recently found the tiniest full-fledged star known, an object just 16 percent bigger than Jupiter, located toward the center of our Milky Way Galaxy.

Considering that there are millions of galaxies apart from ours, there are also millions of stars, bigger and smaller than our Sun, but apart from the planets in our Solar System, we do not still know about the ones that might be in other galaxies. The Universe is immense and there are still a lot of questions to answer about it.

Just to give you an idea, the nearest star to the earth is the Sun at 93 million miles, but the next nearest known star is Proxima Centauri at 4.3 light years -- about 40 trillion miles. You can imagine how difficult is to know more about the space when distances are huge.