Mysterious alien visitor

  This interstellar object called “Oumomo” has always been a mystery, and when it was discovered in 2017, it caused divergent opinions. “Omomo” means “distant messenger” in Hawaiian. It is the first known interstellar celestial body to pass through the solar system. There are many different opinions about what it is and where it comes from. But now, astronomers have given new explanations.
  The mysterious appearance of “Oumomo” took place on October 19, 2017. This morning, astronomers discovered that the Pan-Stellar Project telescope mounted on the Haleakala volcano in the Hawaiian Islands had captured an unusual spot of light, which was rapidly traversing the solar system. The altitude of the Haleakala volcano is 3052 meters, and the observation conditions are very good. The Pan-Star Project Telescope is responsible for monitoring all celestial bodies that may hit the earth. Once a suspicious celestial body is found, the telescope will quickly track its trace, passing speed and location Calculate its orbit.
  The flying speed of “Oumomo” is very fast. Judging from the brightness changes, its shape is very irregular and it is likely to be rolling over and over again. What is even more strange is that people have observed that this celestial body still has puzzling acceleration behavior, so people have various guesses about it: is this an asteroid? comet? Or is it an alien spacecraft?
  ”Oumomo” did first remind people of asteroids, but its strange acceleration behavior made the asteroid’s claim into question. Some people think that it is more like an alien spacecraft that can control its flight status, such as the Light Sail spacecraft. This kind of spacecraft has a huge light sail, which uses the light pressure generated by sunlight to obtain thrust. It is most suitable for long-distance space travel and is an ideal spacecraft for interstellar flight.
  However, this kind of speculation still cannot explain the tumbling behavior of “Aumomo”. This is because the light sail spacecraft needs to keep the sail facing the light source at all times, and compared to the spacecraft for interstellar travel, the running speed of “Ou Mo Mo” seems to be too slow, which makes astronomers more convinced that “Ou Mo Mo” “Is a naturally occurring object.
Locking “Pluto-like celestial bodies”

  In the universe, some naturally occurring objects also exhibit acceleration behavior, the most typical being comets. In the solar system, a comet is a frozen celestial body that usually has an elliptical orbit with a high eccentricity. When they fly by near the sun, the heat of the sun will heat their surface, and some of the material on it will evaporate. The light pressure of the sun and the solar wind push these materials away from the sun, forming a comet tail, which forms comet.
  When the comet is illuminated by sunlight, the ice on the light-receiving surface will evaporate, and the evaporation will give the comet a little rocket-like thrust, and its speed will change. At this point, “Oumomo” is a bit like a comet. After being irradiated by sunlight, it moves slightly faster than the speed allowed by gravity itself, but “Oumomo” is different from a comet because it does not have a tail, which is a typical comet ice. -Caused by ice formed from carbon monoxide or carbon dioxide.


  In order to find the answer, Alan Jackson and Steven Desch, planetary scientists at Arizona State University in the United States, studied this strange object, and they wanted to find out whether there was a similar ice that gave “Omomo” a large enough amount when it evaporated. In this way, its movement can be explained reasonably.
  The amount of force that the evaporated ice exerts on the comet often depends on factors such as how much the ice is heated when it absorbs energy, the mass of ice molecules, and even the crystal structure of the ice. Because the ice, which is composed of nitrogen, hydrogen, and water, evaporates, the thrust exerted on the stars is different. The two scientists found through calculations that nitrogen ice can give “Omomo” a rocket-like thrust, which is more in line with the actual situation. Since nitrogen ice does not cover small celestial bodies such as comets, most of them cover the outer solar system (the inner solar system refers to the area from the sun to the asteroid belt in the solar system. Mercury, Venus, Earth, and Mars are all in the inner solar system. Celestial bodies. Starting from Jupiter, Saturn, Uranus, Neptune, to the Kuiper Belt and Oort Cloud belong to the outer solar system.) On celestial bodies like Pluto and Neptune’s moon Triton, so the two scientists believe that “Omo “Mo” is probably a piece of debris from a celestial body outside the solar system.
  Celestial bodies similar to Pluto are often referred to as “Pluto-like bodies” for short. In our solar system, they exist in the Kuiper belt. In 2015, when the New Horizons probe flew over Pluto, it found that the surface of Pluto was covered with frozen nitrogen, methane, and carbon dioxide. In addition, it has also found vast plains, rolling mountains and flowing nitrogen glaciers. Triton is a similar celestial body. In 1989, when the Voyager 2 probe approached Triton, it found several geysers spewing frozen methane, nitrogen and other ice materials.
“Wanderers” in interstellar space

  Alan Jackson and Steven Desch believe that “Omomo” is likely to be a piece of debris from a celestial body outside the solar system. Is this explanation reasonable? To determine this possibility, the two scientists calculated the probability of a large chunk of nitrogen ice crashing from a Pluto-like body in the early solar system. At that time, the number of Kuiper Belt objects outside Neptune’s orbit was much greater than it is now, including thousands of Pluto-like objects covered in nitrogen. But about 4 billion years ago, Neptune’s orbit expanded. This split caused many celestial bodies in the Kuiper Belt to collide with each other, and most of them drifted out of the solar system.
  Current research shows that collisions between celestial bodies in the Kuiper Belt did occur frequently in the early solar system. For example, Pluto may have encountered an impact, which caused a lot of debris around it and evolved into a satellite cluster. Based on this, scientists speculate that about billions of years ago, the original Pluto and Charon had a violent collision, but the collision did not completely destroy the two celestial bodies. They evolved into two orbiting each other. Planets and moons. The debris from the collision also flooded this newly born system, and finally formed four other very small moons orbiting Pluto.
  According to estimates by Alan Jackson and Steven Desch, in the chaotic solar system at the time, the collision could knock trillions of pieces of nitrogen ice from the celestial bodies. If other planetary systems also throw out the same amount of nitrogen ice fragments, then these objects may occupy 4% of the total number of celestial bodies in interstellar space and become wanderers in interstellar space. After analysis, the researchers believe that although objects like “Omomo” are rare in reality, it is not difficult to find them.
  Regrettably, “Aomomo” is getting farther and farther from the earth. At the end of 2017, it has passed the perigee. In mid-2018, it flew over Jupiter’s orbit and approached Saturn’s orbit, and people could only watch it leave the solar system through a telescope. As a result, astronomers will not be able to confirm whether the two scientists’ views are correct through more observations. But the researchers believe that in the future, the Willa Rubin Observatory and the European Space Agency’s comet interception mission can detect more interstellar objects. It is expected that the Willa Rubin Observatory will find an interstellar visitor every year, and the comet intercept mission may actually visit such a celestial body. The mystery of “Oumomo”‘s identity may still have a chance to be revealed in the world.