Navigation satellites are located at an altitude of 20,000 kilometers and can be navigated by receiving signals within the range they cover. In deep space beyond 20,000 kilometers, a new navigation system is required. Astronomers have proposed several possible navigations The most talked about system is pulsar navigation. Pulsars are a class of neutron stars whose magnetic poles can generate radio or X-ray radiation. When the rotating axis and magnetic poles do not coincide, and the rotating axis sweeps across the earth, pulses are generated Some of these pulsars have very good rotational stability and can be compared to the best atomic clocks on Earth, so these pulsars are also known as "atomic clocks in the universe". If they can receive their signals and know their location, then These pulsars can be used for interstellar navigation. This text is most likely to introduce:. ['Other atomic clocks in the universe similar to pulsars.', 'Some difficulties facing interstellar navigation.', 'Experiments to verify the feasibility of pulsar navigation.', 'Factors affecting the stability of pulsar rotation.']