The Hobby-Eberly Telescope.Image: Marty Harris, McDonald Observatory, UT Austin
The universe we see is only the very tip of the vast cosmic iceberg.
The hundreds of billions of galaxies it contains, each of them home to billions of stars, planets and moons as well as massive star-and-planet-forming clouds of gas and dust, and all of the visible light and other energy we can detect in the form of electromagnetic radiation, such as radio waves, gamma rays and X-rays – in short, everything we’ve ever seen with our telescopes – only amounts to about 5% of all the mass and energy in the universe.