Observations of galaxies and clusters of galaxies indicate that about percent of the matter in the universe is dark matter. 5 25 35 45 95

All the stars, spheres and galaxies that can be perceived nowadays make up just 5 percent of the universe. The former 95 percent is prepared of stuff stargazers can't see, notice or even understand. These secretive substances are called dark energy and dark matter. Experts determine their presence grounded on their gravitational influence on what little bits of the universe can be perceived.

kepler used the data from tycho blahe (his mentor) to construct the laws of planetary motion.

so easy. just google the electromagnetic waves and it’ll pop up.