A vast, flat sheet of dark matter may solve the long-standing mystery of why our neighboring galaxy Andromeda is speeding ...
For more than a century, astronomers have watched in astonishment as the Andromeda galaxy ignored the grand flow of cosmic expansion and hurtled straight toward the Milky Way. While almost every other ...
Plasma propulsion transforms an inert propellant – often hydrogen – into plasma, a superheated mix of ions and electrons.