16 years ago today, August 24, 2006, is destined to be recorded in the history of astronomy. Pluto, which was listed in the ranks of nine planets when it was discovered in 1930, has long been questioned for many differences from the other eight planets. It was finally relegated from the ninth largest planet in the solar system to a dwarf planet at the 26th International Astronomical Union (IAU) and was renamed "Asteroid 134340".
Why is Pluto downgraded?
The existence of Pluto was first proposed by Percival Lowell in the early 20th century, who calculated and proved that the orbits of Uranus and Neptune were caused by the gravity of the unknown ninth planet. Ten years later, on March 13, 1930, astronomer Clyde Tombo confirmed the existence of Pluto at the Lowell Observatory.
Pluto's discoverer Clyde Tombo
Since then, Pluto has firmly sat on the position of the ninth largest planet in the solar system until 2003 astronomers discovered 2003-UB313, also known as Eris, which is almost as large as Pluto but has a much larger mass.
The discovery of Eris has sparked heated debate in the astronomical world, and if Pluto is a planet, then Eris should be too. Therefore, the title and definition of planets were confirmed at the 26th International Astronomical Conference held in Prague, the capital of Czech Republic on August 24, 2006. "Planets" refer to celestial bodies that orbit the sun, have enough gravity to overcome their rigid physical strength, make the celestial bodies spherical, and can clear other objects near their orbits. A celestial body that is not a satellite will be classified as a "dwarf planet" if it only meets the first two criteria.
IAU believes that the necessary conditions for constituting a planet are:
1. Has an orbit around the sun;
2. Has enough mass to maintain the hydrostatic balance (because gravity is pressed into a spherical shape);
3. is the dominant celestial body in its orbit.
Finally, after the International Astronomical Union (IAU) issued a new planetary standard, both Pluto and Ariel were classified as dwarf planets. The IAU finally ruled that Pluto is no longer a planet because Pluto's orbit overlaps Neptune's orbit.
In addition to Pluto and Erik, the solar system also has three known dwarf planets, one is Ceres located in the asteroid belt between Mars and Jupiter, one is Ayushen outside the orbit of Neptune, and the other is Bird God Star located in the Kuiper belt.
Pluto becomes a dwarf planet represents
Pluto is located in the Kuiper belt of the solar system, about 6 billion kilometers away from the earth. It is mainly composed of rock and ice, which is also one of the characteristics of the Kuiper Belt celestial bodies.
When Pluto was still the ninth largest planet, it was the smallest of the nine planets, but when it retreated to the ranks of dwarf planets, it became the largest and second largest dwarf planet in the solar system.
Comparison of Pluto with its satellite "Caron" and the size of the Earth
How should Pluto be described? Let’s compare the moon we know. Its mass is only 1/6 of that of the moon and its volume is only 1/3 of that of the moon. However, Pluto looks much more gorgeous than the moon, and there are three colors on the surface of Pluto: charcoal black, light orange and white.
The components on the surface of Pluto are mainly solid nitrogen, accounting for more than 98%, and the remaining ones are traces of methane and carbon monoxide.
These substances are also distributed differently on Pluto. The side facing the side facing the Netherworld contains more methane, while the side facing the Netherworld has more carbon monoxide and nitrogen.
Since the rocks inside Pluto and the ice layer on the surface will separate under the heat of the decay of radio elements, scientists believe that the internal structure of Pluto has undergone layered changes: the center of the earth is composed of rocks, and the mantle that encloses the center of the earth is composed of ice, and there may be a liquid water layer between the center of the earth and the mantle.
It has a romantic "little heart"
On January 19, 2006, carrying the unknown infinite hope of human exploration and the ashes of Pluto discovered the ashes, NASA's "New Horizons" probe was successfully launched.The "New Horizons" detector is equipped with seven instruments including visible light-infrared imaging spectrometer, remote survey imager, solar wind analyzer, ultraviolet imaging spectrometer, high-energy particle spectrometer, radio scientific equipment, dust counter, etc., which are used to study the composition and temperature of Pluto's atmosphere and surface matter.
"New Horizons" probe
On July 14, 2015, the "New Horizons" probe took a close-up of this distant mysterious planet for the first time, 12,550 kilometers away from Pluto.
At that time, these photos became internet celebrities as soon as they were released. This cold dwarf planet has incredible diversity and complex terrain that shocks imaginative researchers and space fans. There is a bright area of huge heart shape on Pluto, which adds a touch of romantic color to Pluto.
Pluto with a huge "heart shape"
In this huge heart shape, the nitrogen glacier slowly flows into the depths of the cold basin. On the west side of the nitrogen glacier, there is a plateau called "Spangnik". Although it is a plateau, it is not prominent because it is located in the basin. There are many craters on the surface of Pluto, but this "heart-shaped" area can "be out of the mud without staining" and still maintain a smooth surface.
Spangnik Plateau is open and smooth. And it seems to have some mysterious power that makes its surface heal. What's going on? Perhaps the key reason lies in the unique materials that formed this plateau. Nitrogen is the most abundant component in Pluto's atmosphere, but the extremely low temperature makes nitrogen condense into nitrogen ice and fall on the surface of Pluto. The surface of these nitrogen ices on the Sponick Plateau is covered with honeycomb patterns.
honeycomb pattern
Could it be that these strange patterns erased the craters that should have existed? Scientists estimate that the faint heat flow inside Pluto drives the warm nitrogen ice upwards, just like the convection of liquids, high-temperature liquid rises from the bottom and low-temperature liquid sinks from the surface, gradually forming patchwork of honeycomb patterns.
honeycomb pattern formed by liquid convection phenomenon
Nitrogen ice in the atmosphere of Pluto condenses in the lowest place of the crater in the form of nitrogen frost, gradually filling the depression, and "self-healing" becomes the heart-shaped honeycomb plateau we see today.
Nitro ice fills the heart-shaped area on Pluto, and later named after Clyde Tombo, a scientist who discovered Pluto, and is called "Tumo Area". After Clyde Tombo's death, his family packed some of his ashes into aluminum cans, and as the New Horizons probe flew towards Pluto, Tombo, who had never really seen Pluto in his life became the closest human to it. There are still many questions and mysteries about Pluto. All of this may be revealed one by one only if science progresses again, or if humans have the ability to step on Pluto.
Comprehensive editor: CCTV Science and Education, "The Extreme Universe" WeChat official account, Science and Technology Daily
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-