20 19 The BBC recently aired the documentary Planet. Tencent video has been copyrighted in China, and it is updated every Wednesday morning at 10, which is completely synchronized with BBC. Once broadcast, space fans shouted!
"Planet" takes you to appreciate the vibrant planet surface from a novel and unique perspective, witnessing a dramatic moment, telling the past lives of the eight planets and uncovering the secrets of the solar system. Professor Brian Cox explained everything on the planet clearly with an understated tone and knowledge of super dry goods.
After watching the first episode, I felt a vivid cosmic lesson, as if I had followed Professor Cox to the starry sky on the spot.
In the long history, the earth is still. This blue planet is always covered with blue ocean and green land, which looks full of vitality. But in fact, the earth is no different from other terrestrial planets, and it has also experienced great turmoil.
The four Earth-like planets all have unique personalities and their own stories. Planets have described the long history of hundreds of millions of years, and even revealed the possible future development of the solar system. Let us clearly find that the earth will not be suitable for human habitation in the future, and another planet in the solar system will replace the earth and become our new home.
1 mercury
Mercury is the closest planet to the sun, with an average distance of only 58 million kilometers. From an astronomical point of view, this is not a long distance. In fact, such a close orbit means that Mercury orbits the sun once every 88 days. In other words, a year on Mercury is not as long as three months on Earth.
Mercury looks a bit like our satellite moon-full of craters and smooth areas. Although invisible to the naked eye, Mercury is an extreme planet. On the side facing the sun, the surface temperature can soar to 427℃. Imagine that the oven in our kitchen usually cooks at a high temperature of 260℃, so it is really hot on Mercury during the day.
In this photo of Mercury, you can see many long stripes radiating from a crater at the top. These "rays" radiated from the crater can stretch for 1000 km. These rays were formed when the meteorite hit Mercury, and the material under the surface of Mercury was dug out of the crater and thrown out. Due to exposure to the harsh space environment, rays like this will fade over time. Craters with bright rays should be younger because the rays are still visible.
2 Venus
Venus is the second closest planet to the sun and the closest planet to the earth in the solar system. Venus is slightly inferior to the earth in size and quality, and currently has active volcanoes, mountains and rivers (ditches generated by volcanic lava flows). Venus may have an ocean of liquid water in the past.
However, Venus doesn't look like the place we want to live now. Its dense atmosphere is mainly composed of carbon dioxide, which firmly locks the heat that the planet receives from the sun. To some extent, the problem of Venus is just the opposite of that of Mercury. Mercury can't keep the heat of the sun, while Venus keeps too much heat. There is no doubt that this "greenhouse effect" has an impact on Venus: its surface is incredibly hot, reaching 482℃. At this high temperature, any ocean like the earth has already evaporated.
Venus is unique in that it rotates counterclockwise. All the other planets in the solar system (including the earth) rotate clockwise. This means that people standing on Venus will see the sun rising in the west and setting in the east. Why is the rotation direction of Venus so strange? One explanation is that it was hit by a series of large celestial bodies such as asteroids in the early days. These impacts may have generated enough thrust to change the rotation direction of the whole planet in one fell swoop.
There is evidence that Venus probably had liquid water when it was young-this is a necessary factor for life on earth. Some scientists speculate that single-celled organisms can actually survive in the harsh but stable atmosphere of Venus.
3 Earth
The earth is the most complicated phenomenon in the known universe. Among many planets, only the earth produces life, which makes our existence precious.
The location of the earth is just right-it's not too far or too close to the sun. The earth has enough heat to produce liquid water (which is very important for us humans), but there is not enough heat to evaporate all the water.
Combining this suitable temperature range with a thick atmosphere (containing good things such as oxygen) and an active magnetic field that protects us from harmful radiation and space meteorite fragments, it turns out that the earth is the most satisfactory place to live in the solar system.
The idea conveyed in the first episode of Planets is that the earth is unique, living silently in the ever-changing solar system and giving birth to life. This blue planet and its seven brothers and sisters are far more complicated than we thought.
4 Mars
Mars is our neighbor on the other side, farther away from the sun. For decades, Mars has been the focus of science fiction and practical scientific exploration. Pirate satellites entered the orbit of Mars in 1970s, and sent back a lot of information about Mars, which we have always called "Red Planet". Some data show that this planet may have liquid water at some time in the past.
In 2004, NASA returned to Mars in a spectacular way and landed two Mars probes named "Courage" and "Opportunity" safely on the surface of Mars. According to the plan, these two brave robots can run for about 6 months. However, both of them have been running continuously for more than six years, and one of them is still sending scientific data back to the earth until 20 12.
These detectors show that the findings of Viking are just the tip of the iceberg. "Courage" and "Opportunity" found more evidence about water, and found important minerals in the rocks and dust of Mars, which let us see the scenery of Mars that we have never seen before. The latest development of Mars exploration activities is that the Mars Science Laboratory arrived in Mars on August 20 12. This spaceship carries a Curiosity probe, the size of a mini Cooper. In contrast, Spirit and Opportunity are only equivalent to a golf cart, which means Curiosity can carry more scientific equipment, so it should.
Go further than its predecessors.
Titan: the future earth
Titan, the sixth satellite of Saturn (the legendary hometown of Thanos), has a stable atmosphere and is the most likely future home for human habitation in various media reports and scientists' eyes.
There are traces of running water in the rocks on Titan, but the temperature on Titan is as low as-180 degrees Celsius, and water cannot exist in liquid state. Scientists speculate that this is liquid methane, and the photos returned by the detector also prove that there are probably huge methane lakes and oceans on Titan.
Titan is like a cold twin sister of the earth, but if the temperature of the sun rises in 5.5 billion years, Titan may become a new home for mankind.
There are too many mysteries at the top of the Milky Way, and the story about the planets is far from over ... As far as the data we have at present are concerned, the conclusions drawn from scientific observation of the universe are not necessarily the truth or the best theory. But this is also the charm of science!
NASA Encyclopedia of Nature: Understanding the Universe
(NASA scientists write general education courses for the public! A minimalist explanation of the abstruse universe! Yes, very knowledgeable! From the earth, the solar system, the Milky Way, to the depths of the universe, a travel guide spanning 65.438+038 billion light years! 220 real photos taken by NASA Hubble, Chandra and Spitzer telescopes! Alyssa Goodman, a professor of astronomy at Harvard University, recommended it! )