Revisiting Uranus

  The solar system that people recognized before 1781 was much smaller than it is now, with only 6 planets, namely Mercury, Venus, Earth, Mars, Jupiter and Saturn. But at that time, human beings already had astronomical telescopes, and astronomers used telescopes to observe the stars and made discoveries constantly, and human’s understanding of the solar system was constantly changing.
  One night in March 1781, British astronomer William Herschel discovered a strange blue-green celestial object in the starry sky around Taurus and Gemini. William Herschel initially thought it was a comet, but it was later confirmed that the celestial body turned out to be a planet, “Uranus”.
  The discovery of Uranus is very important, it not only “expanded” the territory of the solar system, but also makes people realize that the solar system is not fixed, and the planets are not always limited to just a few. This realization triggered the astronomers’ search for new planets, and the discoveries of Neptune and Pluto were guided by this realization.
  More than two centuries have passed since Uranus was discovered, and human probes have made only one hasty flyby of the mysterious planet. In 1986, the “Voyager 2” probe flew by Uranus, observed the atmosphere of Uranus, and discovered 10 new moons of Uranus. At that time, its closest distance to Uranus was 81,500 kilometers.
  In April 2022, scientists mentioned Uranus again in a report involving planetary missions, and they plan to launch a massive multibillion-dollar mission to send orbiters and sub-rovers to Uranus to explore the planet. Mysterious planet and its moons. Scientists believe that exploring Uranus will help to better understand the icy giant planet in the solar system, thereby helping humans unravel the mysteries of distant worlds.
Mystery of life experience

  Uranus is a gaseous planet with a solid core at the center and a dense atmosphere around it, the main components of which are hydrogen, helium and methane. Uranus’ atmosphere hides storm worlds, with winds sometimes reaching 900 km/h.
  Although we have some basic understanding of Uranus today, there are still many unsolved mysteries that haunt us. Uranus, for example, is very different from other planets in the solar system in that its axis of rotation is almost perpendicular to its orbital axis. What’s going on here?
  It has been speculated that a planet-sized object might have slammed into Uranus in its early days. In the early days of the solar system, this kind of thing happened from time to time, and the Earth may have encountered a similar thing. Scientists believe that shortly after Earth formed, a Mars-sized object slammed into it, and a large amount of debris was thrown into orbit around Earth, where they collided and gathered to form the moon.
  However, the impact that Uranus encountered was even more violent. The celestial body that hit Uranus should have slanted Uranus’s rotation axis, causing Uranus to operate in a very strange state. At the same time, the impact also produced a large amount of dust and gas, which pooled near Uranus’ equatorial plane, forming Uranus’ rings and moons.
  In order to study the “life experience” of Uranus, scientists used computer simulation to deduce the operation state of Uranus in its early years. They concluded from this that in the 650 million years after the formation of the solar system, the distance between Uranus and the sun was actually far greater than that of Neptune, and it was on the periphery of Neptune (now Neptune is on the periphery of Uranus), but then the distance between Uranus and Neptune was The mass changes and their positions are completely reversed. Whether this simulation result is correct, of course, more research is needed to confirm.

Uranus and its 6 large satellites (from left to right: Tianwei 15, Tian Wei Wu, Tian Wei 1, Tian Wei 2, Tian Wei San and Tian Wei Si)
The Mystery of the Satellite

  The moons of Uranus have also been a topic of interest. In 1986, the Voyager 2 probe discovered 10 moons of Uranus. Prior to this, people have successively discovered several moons around Uranus. In 1787, William Herschel discovered the two satellites, Tianwei and Tianwei. Tianwei San is the largest satellite of Uranus. The detection results of “Voyager 2” show that there are a lot of volcanic ash and huge canyons on its surface, indicating that the surface of Tianwei San once had violent volcanic activity, and its interior also once There have been dramatic changes that have shaped the canyon thousands of meters long. Tianweisi is the farthest from Uranus among the large satellites of Uranus, and its volume and mass are second only to Tianweisan. It has numerous craters on its surface, indicating that asteroids and comets have frequently struck it.
  In 1851, the British astronomer William Russell discovered the moon and the moon. The fourth largest of Uranus’ moons, Titan is composed of ice and rock, with newer traces of geological activity on its surface than other Uranian moons. Slightly larger than the moon, Tianwei is the faintest of all the moons of Uranus, and its surface has also experienced many impacts. In 1948, the American-Dutch astronomer Kuiper discovered Tianweiwu. The surface of this celestial body composed of ice and rock is covered with canyons, cliffs and grooves, as well as many cracks and craters. This surface feature has sparked a lot of speculation about what happened to the satellite. Some people speculate that Tianwei’s surface was originally flat, and then it was frequently hit by asteroids or comets. Each impact destroyed part of the original surface and exposed some of the inner material. After many such impacts and changes, Tianweiwu has a strange landform. Later, a new theory emerged: Tianwei Wu once had strong geological activities, and the energy of the activity came from the tidal force of Uranus, which changed the density distribution inside Tianwei Wu, thus creating its strange topography.
  As of 2004, 25 moons of Uranus have been discovered. At the end of 2005, the Hubble Space Telescope captured two new moons of Uranus.

Halo Mystery

  Another great mystery of Uranus is its rings. One day in March 1977, as Uranus orbited in front of a star, astronomers observed that star blinking multiple times, suggesting that Uranus may have multiple rings. After analysis, they believe that there are nine rings around Uranus. When the Voyager 2 probe flew past Uranus in 1986, it discovered that Uranus has 11 rings. In December 2005, scientists announced that they had discovered two new rings with the help of the Hubble Space Telescope.
  The discovery of Uranus’ rings is very important to human understanding of the planetary world. It makes scientists realize that the rings are not unique to Saturn, it may be a universal feature of planets.

Uranus’ rings (photographed by Voyager 2)

  Around 2007 and 2008, the side of Uranus’ rings turned to face the Earth. Astronomers believe that this is the best time to observe Uranus, in addition to the possibility of discovering moons, but also to study Uranus’ rings from a whole new angle. As a result, large astronomical telescopes on the ground and in the sky frequently aimed their lenses at Uranus, and also took clear side photos of the ring. The observations suggest that Uranus’ rings have changed since Voyager 2 detected it. A ring of dust, for example, appears to have moved thousands of kilometers. There’s no definitive explanation for how this movement happened, with one idea being that Uranus’s dust ring has been getting hits all the time, which caused it to move.
  Both Uranus and Neptune are so far away from the sun that they are collectively referred to as “afar planets”. They are located between the orbits of Saturn and Pluto. For the world there, human cognition is still relatively weak.
  Now, plans to explore Uranus are finally on the agenda. According to this plan, the spacecraft to Uranus may be launched in June 2031 or April 2032, pass through Jupiter first, use Jupiter’s gravity to gain acceleration, and arrive at Uranus after 13 years of flight. Once there, the spacecraft will drop a sub-probe into Uranus’ atmosphere, which will sample the composition of Uranus’ atmosphere, while the orbiter will survey the Uranus system in all directions. Amy Simon, a planetary scientist involved in the development of the plan, said: “We are sure that there will be many wonderful new discoveries in this exploration of Uranus.”