There are more than three states of matter
You may have heard about three— liquid, solid, and gas. These are the most common states of matter that we identify here on Earth, but beyond our atmosphere, there is a fourth state — plasma— and it could be the most common in the universe. If you add enough energy to an atom, the electrons will travel away from its nucleus and react with another nearby nucleus, producing plasma, composed of highly charged particles with very high kinetic energy.
Gases like neon are forced into a plasma state by electricity to create glowing signs; stars are literally massive balls of plasma. But that’s not the only extra state of matter: in 1995, scientists developed one called the Bose-Einstein condensate, where matter is super-cooled to almost zero, allowing the molecular motion to basically stop. Nobody knows if Bose-Einstein condensates occur in nature, but they can be made in a laboratory. Researchers are also examining other states of the matter, so that the number will continue to rise, according to Gizmodo.
We either have eight or 13 planets in our solar system
My sixth-grade science teacher taught us “Mary’s violet eyes make John stay up nights plenty” (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto)—but instead, in the 1990s, scientists discovered a doughnut-shaped region of the solar system beyond Neptune that was packed with asteroids, comets, and icy objects. They named it the Kuiper Belt, redefining the poor little Pluto as a Kuiper Belt Object instead of a planet.