Nilakshi Veerabathina at The Conversation: Space, or outer space, is a vast, near-perfect vacuum largely devoid of matter. This vacuum contains very few particles compared with Earth’s atmosphere. However, it’s not entirely empty.
Space is dotted with scattered matter called the interstellar medium, which includes hydrogen and helium atoms. These are the most common elements in space, and they exist in both charged and neutral forms. The interstellar medium also contains cosmic dust – tiny particles of various elements, including carbon and silicon, scattered throughout space.
High-energy particles called cosmic rays – which are primarily protons and the nuclei of atoms – travel through space at nearly the speed of light. Cosmic rays come from various stars including our Sun, as well as from supernovae, the material falling into black holes, colliding galaxies and more.
Space is filled with various forms of radiation, including cosmic microwave background radiation. This is remnant heat from the origin of the universe. High-energy cosmic events like supernovae and black holes also emit X-rays and gamma rays.
Magnetic fields generated by stars, planets and many other celestial bodies also permeate space. These fields influence the motion of charged particles by attracting or repelling them like magnets.
Dark matter and dark energy
Scientists predict that an as-yet unseen form of matter that does not emit light or energy, called dark matter, makes up a significant portion of the universe’s mass. Researchers guess that it exists because they can see its gravitational pull on other visible matter.
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