The Neutron star Interior Composition Explorer (NICER) mission will study neutron stars, the densest known objects in the cosmos. These neutron star animations and graphics highlight some of their unique characteristics.
NICER observes X-ray light from the surfaces of neutron stars. In these strong-gravity environments, light paths are distorted so that NICER can see emission from the star's far side, especially for smaller, denser stars.
With the mass of 1.5-2 suns compressed into a city-size volume, neutron stars exert a powerful gravitational force, even on the light emitted from their surfaces. For a fixed mass, the smaller the star, the more strongly light paths (pink arrows) are "bent," so that a distant observer (to the right, in this animation) can see more of the otherwise invisible far side of the star.