Hi Jenny, great question! To answer your question, the same materials do exist in other planets. We know this because when we observe other planets we can use the color of light waves to learn about materials on other planets. You can think of your own unique handwriting signature. Well, elements like Oxygen have their unique light signature which gives astronomers information! This is called "remote sensing" technology. Also it's amazing to learn how different other planets are from Earth! Some hydrogen gases exist in massive amounts on Jupiter. Some planets and even asteroids can contain rare metals like platinum and gold. Let's remember, Earth is very special by itself, because of the liquid water found here. Our oceans, lakes and rivers are unique in the known universe. This allows all of us to live and grow here!

Our current theories of cosmology (theory of the origin and development of the universe) tell us that all of the stars, planets, and other visible, detectable objects in our universe are made of the same set of materials. Based on what we can measure, we either observe or infer ("infer" means to logically but indirectly use evidence to reach a conclusion) that some stars/planets have more of certain types of materials than others, and some stars/planets/other objects do not have certain types of materials at all.

For example, we know that the atmosphere of Venus? is mostly carbon dioxide, with a bit of nitrogen, and very, very little of other gases. Based on the evidence we have of the current state of Venus, we can say that there is currently no breathable oxygen on Venus. The short answer here is that some materials we find on Earth may not exist on some other planets at this moment, but that does not mean that these materials did not exist on other planets in the past or will not appear on other planets in the future. We know too little of this astronomically massive universe for us to say one way or another.