Video spoilers history, starting with the blitzkrieg on Poland

The new sky is the universe.

In the deep darkness, the camera moves forward rapidly, and the blazing solar flares dance like flames, at the edge of this golden flame.

A tiny silver-gray silhouette slowly emerged.

It’s Mercury!

The sound of the sky began to play as the sun and Mercury danced.

【Mercury, ancient Chinese astronomers called it "Chenxing". 】

[In the West, it is named after Mercury, the Roman god of commerce, travel, and theft.]

[For Mercury moves faster in the sky than any other planet, just as swiftly as the movement of this god.]

[From the name, "Mercury" seems to be closely related to water, but in fact, it is an extremely dry planet. ]

[Mercury is the smallest planet in the solar system.]

[The average diameter is only about 4880 kilometers, not much larger than the Earth's satellite, the Moon.]

[But don't underestimate it, Mercury has an extremely high density, reaching 5.43 grams per cubic centimeter. ]

[It is the second densest celestial body in the solar system after the Earth. ]

[This means that Mercury has an extremely dense interior structure.]

[Scientists speculate that there may be a huge metal core inside Mercury. ]

[It is estimated that Mercury's iron core accounts for about 57% of its total volume, like a giant iron ball wrapped in a rocky shell.]

[This ratio far exceeds that of other terrestrial planets. ]

[In comparison, Earth's inner core accounts for only 17 percent of its diameter.]

[Such a special internal structure makes Mercury a living fossil for studying the formation of planets. ]

[Regarding its origin, the most mainstream theory is that Mercury suffered a devastating impact in the early days of the solar system, causing most of the lighter mantle material to be stripped away.]

【Only this high-density metal core is left. 】

[This hypothesis explains why Mercury is so different.]

[Some people also say that it was the tidal heating of the early sun that "burned" the outer layer of Mercury like a baked sweet potato and blew it away.]

【There is another view. 】

[Mercury was born about 45 billion years ago, condensing from a vortex of dust and gas left over from the formation of the sun.]

【But some scientists believe. 】

Mercury may have formed in the asteroid belt within the solar system.

[The surface of Mercury looks very similar to the moon, and is covered with craters of various sizes. ]

[These impact craters record billions of years of bombardment by asteroids and comets.]

[The most notable of these is the Caloris Basin.]

[This huge impact crater with a diameter of 1550 kilometers may be the product of a violent collision in the early solar system. ]

[Interestingly, just opposite the basin, scientists discovered an unusually rugged terrain, known as the "weird terrain."]

[This may be the result of the shock wave from the huge impact passing through the entire planet, causing crustal deformation on the other side.]

[Mercury's surface is also dotted with cliffs that are hundreds of kilometers long.]

These features, called lobate scarps, are spectacular formations formed when the Earth's crust fractured as the planet's interior cooled and contracted.

[Extreme temperature changes are one of Mercury's most notable features.]

[With almost no atmosphere to protect it, the temperature difference between day and night on Mercury's surface is surprisingly large. ]

[At noon when the sun is shining directly, the surface temperature can soar to 427°C, hot enough to melt lead and tin.]

【At night, the temperature drops to -173℃.】

[Such extreme temperature differences are unique in the solar system.]

[Even more surprising is that despite such a hot surface, Mercury has a large amount of water ice in the permanently shadowed polar regions.]

……

Outside the sky.

Early Han Dynasty.

Liu Bang was also surprised when he saw the picture on the sky that Mercury actually had a large amount of ice.

Originally, Liu Bang was not an astronomy enthusiast or ancient scientist.

But looking up at the stars is human nature.

Liu Bang also watched this popular science article about Mercury with great interest.

When Liu Bang saw the distance between Mercury and the sun and the terrifying temperature, he kept thinking:

This planet called Mercury is clearly a scorching hell planet.

But Tianmu said that this planet with a temperature of hundreds of degrees that can easily boil a person into carbon actually has a large amount of ice!

Liu Bang couldn't help but sigh with surprise and laughter:

"It's amazing! Mercury is a planet close to the sun and extremely hot, but it can have a lot of water."

"Why do I feel that the more cosmic astronomical knowledge the sky curtain tells me, the more confused I am about the universe?" Liu Bang muttered to himself.

"How did the humans of later generations explore Mercury?"

……

[Confirmed in 2012 by radar observations from the MESSENGER probe.]

[These ice layers deep in polar craters may be several meters thick and the total amount may exceed 1 trillion tons! ]

[This water should have been brought by comets. ]

[This discovery is a miracle in the universe! ]

[You know, the temperature on Mercury is extremely high, and water ice should evaporate instantly, but in some permanent shadow areas at the poles, the temperature is extremely low, allowing the water ice to be preserved.]

[The existence of these ices overturns people’s traditional understanding of this fiery planet. ]

[It also provides important clues for studying the distribution of water in the solar system. ]

[Mercury's orbital motion is equally fascinating.]

[It is the fastest planet in the solar system, orbiting the sun in just 88 Earth days.]

[But its rotation is extremely slow, with one Mercury day being equivalent to 176 Earth days.]

【This special state of motion is called "3:2 orbital resonance." 】

[That is, for every two revolutions of Mercury around the sun, it will rotate three times.]

This unique pattern of motion causes puzzling time phenomena on Mercury.

[If you stand at certain locations on the surface of Mercury, you will see the sun rise, then pause, or even briefly move backward before continuing its journey.]

[This kind of "retrograde sunrise" spectacle cannot be seen on other planets. ]

[Mercury's atmosphere is so thin that it is almost negligible.]

[The so-called "exosphere" of Mercury is mainly composed of atoms brought by the solar wind, including helium, sodium, oxygen and other elements. ]

[Because Mercury's gravity is weak, these atoms quickly escape into space, so the atmosphere needs to be constantly replenished.]

[Such a thin atmosphere can hardly provide any protection for the surface of Mercury. ]

[This exposes Mercury to cosmic radiation and meteoroid impacts.]

[This also explains why Mercury cannot maintain a stable climate like the Earth.]

[At the same time, this also causes the sky of Mercury to be always pitch black. ]

[Even in the daytime, you can clearly see the twinkling stars. ]

[Mercury's magnetic field is an unsolved mystery in the scientific community.]

[It stands to reason that the core of such a small planet should have cooled and solidified long ago, but it has a global magnetic field similar to that of the Earth.]

[Although the intensity is only 1% of the Earth's, it is enough to deflect the solar wind and form a mini magnetosphere. ]

[The latest research also found that the current flowing in Mercury's magnetosphere is not a westward ring current like the Earth's, but a unique eastward current. ]

[It's like opening a reverse lane in the solar system.]

[This abnormal phenomenon may be related to Mercury's super-large iron core. ]

[But it could also be the product of the interaction between the solar wind and the tenuous exosphere.]

Mercury has special significance for human exploration of the universe. As the planet closest to the sun, it endures the harshest space environment.

[Studying it can help scientists understand how planets evolve under extreme conditions.]

【Mercury's high-density core and active geological history.】

[It also provides a unique sample for studying the formation of terrestrial planets.]

[The discovery of polar water ice has triggered a rethinking of the distribution of water resources in the solar system. ]

【Perhaps when humans can study Mercury. 】

【Humanity will then be able to truly leave the solar system. 】

……

Barrage:

"Looking at the scale diagram of the solar system, it feels like Mercury is about to fall into the sun."

"I wonder what it would be like to watch the sunrise on Mercury."

“That must be very oppressive.”

"The idiom 'living day by day like a year' is very scary. Did the ancients land on Mercury in the early days?"

"On Mercury, you can follow the boundary between day and night, and it won't be too hot or too cold."

"When I was a kid, I thought the entire planet of Mercury was boiling water."

"I went to plant Hami melons. The temperature difference between day and night was huge. I wore a cotton jacket in the morning and a gauze dress in the afternoon, and ate watermelon under the sun."

"The more I watch, the more I feel that human beings are insignificant and sad."

"My daily feeling when watching astronomy is to doubt life."

"Starry Sky! How wonderful it would be if I were born in an era where free space exploration is possible!" (End of this chapter)