Xiao Yu’s fleet didn’t stop at Uranus, as the planet was on the opposite side of the Sun during this period. However, calculations suggested that after traveling another two billion kilometers, the fleet would reach Neptune’s orbit, offering a rare opportunity for a close observation of the distant blue giant.

At this moment, Xiao Yu’s fleet was traveling at a velocity of 500 kilometers per second relative to the Sun.

During this long journey, Xiao Yu arranged his fleet into a spherical formation. At the core of the sphere were the three “County-Class” spaceships, surrounded by seventy “Town-Class” ships. Encircling them were a thousand “Village-Class” ships, forming a structure like stars orbiting a moon. This vast sphere, with a diameter of 10,000 kilometers, housed Xiao Yu in its center, where he commanded the enormous fleet as it streaked through space.

Between ships, a minimum distance of 500 kilometers was maintained. In the fleet’s vanguard, the “Village-Class” ships handled patrol duties, frequently firing lasers to vaporize small asteroids obstructing their path. Like a giant crab crashing through the solar system, Xiao Yu’s fleet advanced unimpeded.

Ahead, the blue, ocean-like Neptune entered Xiao Yu’s view. Here, he observed the planet’s magnificent Great Dark Spot and had a close-up look at Triton.

Triton, once a Kuiper Belt object, was captured by Neptune’s powerful gravity, resulting in its retrograde orbit. Slowly, it was inching closer to Neptune. Once Triton crossed Neptune’s Roche limit, the moon would be torn apart by Neptune’s gravitational forces, and its fragments would rain down upon the planet. This cataclysmic event would rival the scale of the Jupiter-Moon Collision but, due to the vast distance, would have little impact on the inner planets.

Xiao Yu did not decelerate his fleet. Having resolved to leave the solar system, no scenery, no matter how breathtaking, could sway him.

The encounter with Neptune was fleeting. Not only did Xiao Yu avoid stopping, but he also used Neptune’s gravity to accelerate his fleet to a velocity of 520 kilometers per second.

A month later, Xiao Yu’s fleet reached Pluto’s orbit. Gazing through his telescope at the distant dwarf planet, over three billion kilometers away, Xiao Yu expressed a silent sympathy for it before continuing his journey into the outer solar system.

Here, the fleet entered the Kuiper Belt. This region is the primary source of the solar system’s short-period comets. Famous comets like Halley’s Comet are believed to originate here, though Xiao Yu was not fortunate enough to encounter it—Halley’s Comet was likely wandering in some obscure corner of the solar system.

This far from the Sun, at a distance of six billion kilometers, the Sun appeared no brighter than Venus does from Earth. It had become a mere point of light, stripped of all discernible features. Yet, even at such a distance, the Sun continued to dominate everything in its domain. Kuiper Belt objects like Pluto, Eris, and Sedna, along with countless icy rocks, still revolved around this distant point of light.

Here, the environment was cold and dark. Solitude was the eternal rhythm of the universe, while light was an exceedingly rare spectacle.

At least a hundred million celestial objects were scattered throughout this vast expanse. Yet, to Xiao Yu, it was as though there was nothing. Compared to the immensity of space, the material density was staggeringly low.

Undeterred, Xiao Yu pressed forward. In the vacuum of space, with no reference points, movement was imperceptible. His enormous fleet floated silently in the void, seemingly still and lifeless.

Xiao Yu closely monitored the strength of the solar wind. Over the nine-month journey, he observed its velocity gradually decreasing, indicating that the Sun’s influence was waning in this region.

Slowly, the solar wind’s speed decreased from hundreds of kilometers per second to subsonic speeds of 340 meters per second. Xiao Yu realized that he had reached the edge of the solar system.

Beyond lay the boundless realm of interstellar space. Here, the Sun’s powerful energy carved out its own dominion within the interstellar medium. Xiao Yu now stood at the border between the Sun’s empire and the interstellar medium.

This was the heliopause, the boundary of the solar system, located 18 billion kilometers from the Sun.

Under the influence of interstellar medium, the solar wind’s velocity finally dropped below the speed of sound. Here, the solar wind and the interstellar medium engaged in a fierce battle, with countless particles colliding in places invisible to the naked eye. The temperature in this region reached several thousand degrees Celsius.

Yes, despite the icy darkness where humans would instantly freeze into solid blocks, the temperature here was thousands of degrees Celsius.

Temperature, after all, measures the kinetic energy of particles. In this region, the material was so sparse, so tenuous, that the high temperature posed no threat to Xiao Yu. It was akin to Earth’s ionosphere, where temperatures exceed a thousand degrees Celsius, yet satellites move freely within it.

This was the ultimate battlefield. In the clash with the interstellar medium, the solar wind was utterly defeated. Xiao Yu understood that beyond this point, apart from its gravitational pull, the Sun would have no further influence.

It took Xiao Yu two days to traverse the heliopause. As he watched the number of high-energy solar particles detected by his instruments gradually dwindle and finally vanish, he gazed at the faint, indistinct dot that was the Sun. No longer distinguishable from the myriad stars around it, the Sun stirred a profound and indescribable emotion in Xiao Yu.

“Goodbye, Mother. Goodbye, my beloved Mother,” Xiao Yu murmured, overwhelmed by a sudden urge to weep.

Beyond lay the domain of interstellar medium, the realm of hydrogen and helium from the Milky Way. Here, matter was so sparse it defied imagination, with less than one atom per cubic centimeter—a density akin to spreading a single drop of water across a volume of five million cubic kilometers.

Ahead awaited a journey through such desolation, spanning over 6,000 years of solitude.

After leaving the heliopause, Xiao Yu fell into a year-long depression. During this time, he was in a perpetual state of mental haze, leaving the fleet’s operations entirely to automated systems. Xiao Yu spent his days staring through telescopes, fixating on the distant Sun, lost in memories. Fortunately, the pre-programmed course ensured that no asteroids or other threats jeopardized the fleet’s safety.

By now, Xiao Yu was 35 billion kilometers from the Sun. Light from the Sun took 32 hours to reach this distance. In this remote expanse, Xiao Yu made a groundbreaking discovery.

He found a planet.

Yes, a celestial body that had achieved hydrostatic equilibrium and possessed the mass necessary to clear its orbital path. By all criteria, this object met the astronomical definition of a planet.

Its mass was 1.5 times that of Earth, and it was a rocky planet with an extremely slow orbit around the Sun, taking 732 years to complete one revolution.

Observing this planet, Xiao Yu experienced a sudden clarity, understanding much that had eluded him before.

Humanity had long speculated about the existence of another large planet beyond Pluto’s orbit to account for the peculiar orbital paths of many Kuiper Belt objects. Now, Xiao Yu had finally found the answer.

Indeed, a large planet existed here. However, due to its small size and the region’s extreme darkness, humanity had never detected it.

Xiao Yu named this celestial body “The Lost Star.” It was a forgotten place, unrecorded in human history or texts.

Xiao Yu poured significant effort into studying the Lost Star. He hastily constructed and launched a satellite into its orbit, ensuring he could continue observing the planet even as his fleet journeyed farther away.

The Lost Star lacked an atmosphere, but Xiao Yu detected what appeared to be liquid nitrogen on its surface, as well as solid white substances resembling water ice. This suggested that under suitable conditions—where water ice could melt and nitrogen could sublimate—it might develop an atmosphere akin to Earth’s.

The planet featured mountain ranges, indicating a history of tectonic activity. This, in turn, suggested the presence of a molten, heated core. Such conditions could imply volcanic eruptions and geothermal springs. Where there were hot springs, there was the possibility of life.

Xiao Yu’s mind raced with thoughts.

For an entire year, Xiao Yu observed the Lost Star until he could no longer receive signals from the satellite. Reluctantly, he abandoned further study of the planet.

The discovery of the Lost Star revitalized Xiao Yu, pulling him out of his despondency and reigniting his thirst for exploration.

He resumed compiling the Chronicles of Heroes Across the Cosmos, restarted research on superluminal communication, anti-gravity technology, and next-generation spacecraft propulsion systems. Studies in physical theory also intensified, with computational tasks for the main computer scheduled 300 years into the future.

In other words, the calculations required for these tasks would keep the main computer running at full capacity for three centuries. This realization made Xiao Yu smile wryly. However, on such a journey, time was abundant, and Xiao Yu was in no hurry.

Time passed in this lonely yet fulfilling state. After his encounter with the Lost Star, Xiao Yu found no other objects of interest for the next 600 years.

Six centuries later, Xiao Yu reached a significant milestone.

He arrived at the Oort Cloud, a region approximately one light-year from the Sun.

Source: Webnovel.com, updated by NovelKeep