A 42-light-year-long X-ray tail has been discovered connecting a pulsar to ultrahigh-energy gamma-ray emissions that had previously been called "orphan" because their source was unclear. This discovery was made using data from China's Einstein Probe satellite and the Large High Altitude Air Shower Observatory (LHAASO). The X-ray tail, stretching from the pulsar PSR J1740+1000, aligns with the direction of the gamma-ray emissions detected by LHAASO, suggesting a possible link between the two phenomena. The tail was observed using the Follow-up X-ray Telescope on the Einstein Probe, which is designed to detect faint and diffuse X-ray structures due to its wide field of view and low background noise. The observations, totaling around 70,000 seconds of exposure, showed that the tail extends southwest from the pulsar for about 32 arcminutes. At the pulsar’s distance of 4,600 light-years, this corresponds to approximately 42 light-years. This indicates that the tail is not a small, localized structure but a long path of high-energy particle movement spanning tens of light-years. Scientists believe the X-ray and gamma-ray emissions come from the same group of high-energy electrons. These electrons are accelerated to extreme energies within the pulsar wind nebula and then travel along the tail, interacting with magnetic fields and emitting synchrotron radiation, which is observed as X-rays. At the same time, these electrons interact with low-energy photons in space, boosting them to ultrahigh energies and producing the gamma rays detected by LHAASO. The study suggests that high-energy particles can travel considerable distances without spreading out randomly in all directions. Researchers have proposed two possible explanations for this: one is that the interstellar magnetic field is highly ordered, allowing particles to move along the field lines while restricting movement perpendicular to them, creating a narrow "magnetic track." The other possibility is that a fast, focused outflow continuously carries the particles in a specific direction. This discovery provides new insights into how high-energy particles escape their points of origin and travel through space. It also offers a fresh perspective on ultrahigh-energy gamma-ray sources in our galaxy, suggesting that the locations where such radiation is detected may mark the end of a long journey for the particles, rather than their starting point. The findings were published in Science China: Physics, Mechanics & Astronomy on September 21.