Uranus is the seventh planet from the Sun, 51,118 km. It is about 65 times the size of Earth, second only to Jupiter and Saturn among the nine planets. Uranus' atmosphere is 83% hydrogen, 15% helium, 2% methane and small amounts of acetylene and hydrocarbons.

Methane in the upper atmosphere absorbs red light, giving Uranus a blue-green color. The atmosphere gathers into clouds at fixed latitudes, similar to the bright strips of color on the latitudes of Jupiter and Saturn. The average temperature of Uranus' clouds is minus 193 degrees Celsius. The mass is 8.6810±13×10²⁵kg, which is equivalent to 14.63 times the mass of the Earth. The density is smaller, only 1.24 g/cm3, which is 74.7% of Neptune's density value.

Neptune is the eighth planet from the Sun, with a diameter of 49,532 kilometers. Neptune's orbit around the Sun has a radius of 4.5 billion kilometers and takes 165 years to complete one revolution. From its discovery in 1846 to the present day, Neptune has not completed a full journey. Neptune is similar in diameter to Uranus and slightly more massive than Uranus. Neptune and Uranus are mainly composed of hydrogen and helium, and their internal structures are very similar, so Neptune and Uranus are twin brothers.

Neptune has the strongest winds in the solar system, measured at speeds of up to 2,100 kilometers per hour. The temperature at the top of Neptune's cloud is -218 °C, making it one of the coldest regions of the solar system. The temperature of Neptune's core is about 7000 °C, which can be compared to the surface of the Sun. Neptune was discovered on September 23, 1846, and is the only planet to be discovered using mathematical predictions rather than planned observations.

Pluto, located on the inner side of the Kuiper Belt beyond Neptune, is the largest known object in the Kuiper Belt. The diameter is about 2370±20km, which is 18.5% of the Earth's diameter. On August 24, 2006, the General Assembly of the International Astronomical Union voted on the 24th to no longer consider Pluto, one of the traditional nine planets, as a planet, but to include it as a "dwarf planet".

According to the resolution adopted by the General Assembly, "planets" are celestial bodies orbiting the Sun, whose gravitational pull is sufficient to overcome their rigid physical strength to render a celestial body spherical and capable of clearing other objects in the vicinity of its orbit. Of the "nine planets" of the solar system's tradition, only Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune meet these requirements.

Pluto was automatically downgraded to a "dwarf planet" because its orbit intersected Neptune's orbit and did not meet the new definition of a planet. Pluto's surface temperature is roughly between -238 and -228°C.

Pluto's composition is made up of a mixture of 70% rock and 30% icy water. The shiny part of the Earth's surface may be covered with some solid nitrogen and small amounts of solid methane and carbon monoxide, and the dark part of Pluto's surface may be some basic organic matter or a photochemical reaction triggered by cosmic rays.

Pluto's atmosphere is mainly composed of nitrogen and small amounts of carbon monoxide and methane. The atmosphere is extremely thin, with only a small micropascal of ground pressure.

Earth, the third planet from the Sun, is the home of our humans, and although Earth is an ordinary planet in the solar system, it is unique in many ways.

For example, it is the only planet in the solar system that is mostly covered in water, and the only planet known to have life. Mass M=5.9742 ×10^24 kg, surface temperature: t = - 30 ~ +45. British researchers report in the journal Astrobiology that the Earth would have been habitable for about 1.75 billion years without events such as asteroid impacts that could dramatically alter the environment, although human-caused climate change could shorten that time.

No one knows if they can win this protracted war without preparation, so they need to know more about their planet, the galaxy they are in. Hua Feng knew this very well, as the hardest working among this group of students, he didn't dare to relax for a moment.

Comets are a class of small celestial bodies in the solar system made up of dust and ice that orbit the Sun.

Scientists used detectors to analyze the comet's chemical remnants and found that the main components were ammonia, methane, hydrogen sulfide, hydrogen cyanide and formaldehyde. Scientists concluded that the comet's smell smelled like a combination of rotten eggs, horse urine, alcohol, and bitter almonds.

Around the solar system is a huge "Oort cloud". The nebula is dotted with countless ice, snow and gravel. Some of these are gravitationally influenced by the sun's attraction and fly into the inner solar system, which is called a comet. These ices, snow, and debris enter the inner solar system, where their surfaces begin to volatilize due to the solar wind.

So comets have a long tail, and the closer they get to the Sun, the longer and more pronounced the tail becomes. Interstellar space within the solar system is not vacuum, but is filled with all kinds of particles, rays, gases, and dust.

The Kuiper Belt is a theory that short-period comets are a ring from 50 to 500 AU above the Sun, located at the end of the solar system. The Kuiper Belt is a giant ring of icy fragments that lies beyond Neptune's orbit and orbits the outer edge of the solar system.

Material Diversity:

A red giant, when a star passes its long adulthood, the main-sequence stage, and enters old age, it will first become a red giant. Calling it a "superstar" is to highlight its huge size.

During the giant phase, the size of the star will expand to as much as a billion times. It is called a "red" giant because as the star expands rapidly, its outer surface is getting farther and farther away from the center, so the temperature will decrease and the light emitted will become more and more reddish. However, although the temperature has decreased a little, the red giant is so large that its luminosity has become very large and extremely bright. Once the red giant is formed, it heads towards the star's next stage, the white dwarf.

A white dwarf is a low-luminosity, high-density, high-temperature star. Because of its white color and relatively small size, it is named a white dwarf. White dwarfs are a very special kind of celestial objects, which are small in size and low in brightness, but have large mass and extremely high density. White dwarfs are the terminus of the evolutionary route of low- and medium-mass stars.

At the end of the red giant phase, the center of the star stops producing energy due to insufficient temperature, pressure, or when nuclear fusion reaches the iron phase. The gravity of a star's shell compresses the star to produce a high-density celestial body. A typical stable, independent white dwarf has about half a solar mass, slightly larger than Earth.

This density is second only to neutron and quark stars. If the mass of a white dwarf is more than 1.4 times the mass of the Sun, then the charge repulsion between the nuclei is not strong enough to resist gravity, and the electrons are pressed into the nucleus to form a neutron star. Atoms are composed of nuclei and electrons, and the vast majority of the mass of atoms is concentrated in the nucleus, and under tremendous pressure, electrons will break away from the nucleus and become free electrons.

This free electron gas will occupy as much space between the nuclei as possible, so that the amount of matter contained in the unit space will also be greatly increased, and the density will be greatly increased.

Figuratively speaking, the nucleus is "immersed" in electrons, often referred to as "degenerate states". Most of the star's inner core is burned by hydrogen fusion, converting mass into energy, and producing light and heat, and when the hydrogen fuel inside the star is consumed, it begins to undergo helium fusion reactions and forms heavier carbon and oxygen, a process that is relatively brief for stars like the Sun, and forms a white dwarf composed of carbon and oxygen, and if its mass is greater than 1.4 times the mass of the Sun, a type Ia supernova explosion will occur.

Quasars, since the 60s of the 20th century, astronomers have also found a kind of object that behaves as a point of light outside the Milky Way like a star, but in fact its luminosity and mass are the same as galaxies, we call it quasars, and thousands of such objects have been found now. A supernova is a stage in the evolution of stars. A supernova explosion is a violent explosion that certain stars experience near the end of their evolution. It is generally believed that stars with masses less than 9 times the mass of the Sun cannot form supernovae after undergoing the process of gravitational collapse.

In the late stage of the evolution of massive stars, no new energy can be produced inside, and the huge gravitational force rapidly collapses the entire star towards the center, pressing the central matter into a neutron state to form a neutron star, and the material that collapses under the outer layer encounters this hard "neutron nucleus" and rebounds and causes an explosion. This is called a supernova explosion, and when the mass is greater, a black hole can form in the center. The amount of energy released during a supernova explosion would take our sun to burn for 90 billion years to match it.

Supernova research has deep implications for the fate of humanity itself. If a supernova erupts very close to the Earth, and the international astronomical community generally believes that this distance is within 100 light years, it can have a significant impact on the Earth's biosphere, and such a supernova is called a near-Earth supernova. Some studies believe that the Ordovician mass extinction in the history of the earth was caused by a near-Earth supernova, which led to the disappearance of nearly 60% of the earth's marine life at that time.

Pulsars, which are the products of a star that explode during the supernova phase. After the supernova explodes, there is only one "core" left, only a few tens of kilometers in size, and its rotation speed is very fast, and some can even reach 714 revolutions per second. In the process of rotation, its magnetic field will cause it to form strong radio waves to radiate to the outside world, pulsars are like beacons in the universe, continuously emitting electromagnetic waves to the outside world, this electromagnetic waves are intermittent, and have a strong regularity.

It is because of their strong regularity that pulsars are considered to be the most accurate clocks in the universe.