Lead
In December 1972, NASA's astronauts on the space shuttle Apollo 17 officially embarked on their third mission to the moon, flying to space at a distance of about 29,000 kilometers from Earth.
At this distance, the astronauts took a photograph of the Earth and transmitted it to scientists on the ground.
The main content of this photo is a "blue marble" floating in the universe, and since most of the earth is covered by oceans, the color tone on the photo is mainly blue.
In addition, because the Earth's equator and low-to-mid latitudes are illuminated by the ocean, you can also see white and green, representing white clouds and greenery, respectively.
This photograph was known as the "blue marble" at the time because of its bright color and visual beauty.
But on the other hand, the photograph has a deeper meaning, that is, it shows a panoramic view of the Earth, depicting the main characteristics of the Earth as a living planet.
In the next billion years, the Earth may also lose its environment suitable for life due to changes in the sun, so humanity may lose life planets in the coming days.
So how does this photo show the characteristics of the earth, and how does the sun affect the survival of the earth?
1. How many planets in the universe are there life?
As the only planet in the solar system with life, life on Earth was formed millions of years ago and has evolved since then.
Life on earth can be said to be deeply rooted in the hearts of the people, and almost all life in the world is inseparable from the earth.
In the universe, the position of the Earth is lonely, and its loneliness is also manifested in the solar system, because the Earth is the only planet in the solar system that has life.
In front of the planet with life, there are two other planets in the solar system, Mars and Venus, which are also the closest to the earth, and of course the most suitable planets for life.
Mars and Venus, as natural planets in the solar system, like Earth, both had oceans in the early stages of formation, so they have the basis for the emergence of life.
At present, scientists have discovered more than 4,300 planets outside the solar system in the universe, but whether these planets have life or not, human beings still have no way of knowing.
But the discovery of life on Earth still excites human beings when exploring life in the universe, because with the existence of the earth, scientists believe that there must be life in outer space, but the lack of technology has not yet been discovered by humans.
However, there are also rare planets that have proven to be unsuitable for life, either because they are too close to the sun to erupt volcanoes and other phenomena, or they have no magnetic field to withstand the deadly catastrophe brought by the sun.
Because the earth is so suitable for life, there are billions of years of origin and evolution of life, and finally the scene of the recovery of all things is formed.
In fact, there are still a lot of planets that can survive in the universe, and each planet has its own surprises, so it can be said that the universe has countless homes.
2. The three living planets of the solar system.
So what are the energy sources of the three closest planets to Earth, Venus and Mars?
On Earth and Venus, the energy brought by the Sun is the same, while Mars is far away from the Sun, the energy will gradually weaken.
But in fact, Mars absorbs the energy of the Sun very well, and there is an ordinary temperature in its equatorial region, and there is even a very large temperature difference.
The Earth and Venus receive the same amount of energy from the Sun, but the Earth is closest to the Sun, so the energy absorption is also very sufficient.
Venus, on the other hand, deviates from the Sun, so it absorbs much less of the Sun's energy, so the temperature on Venus will be very high.
Both Earth and Venus had oceans in the early days, but as the stars intervaled, the temperature of Venus rose dramatically, causing the oceans on Venus to gradually evaporate.
Mars is in the last second between leaving the star, the temperature is still very cold, and the atmosphere on Mars is very thin.
The oceanic histories of the three planets are also different, and the oceans on Mars are so shallow that the deepest places are only a few tens of meters deep.
The oceans of Venus and Earth are much wider and deeper, so the demise of the oceans on Mars is even faster.
The earth is relatively short in terms of the interval between stars, so the existence of the ocean is very precious, providing a valuable condition for the emergence of life.
When the Sun completes its entire star cycle, it becomes an even larger red giant, which eventually loses its original shape, and the Earth eventually disappears due to the changes in the Sun.
The sun will continue to expand until this day, causing the temperature to continue to rise, and eventually become a planet similar to Venus, thus making life on Earth unavailable.
And the sun is constantly developing, and with every second of its development, it becomes brighter and hotter, and it will soon reach a period when life on Earth cannot survive.
When the expansion of the Sun reaches this stage, all life on Earth will disappear and then become a hot planet under the expansion of the Sun.
From the perspective of the solar system, the Earth is the most powerful planet after the Golden Phoenix, and it is also the only planet that can support the existence of life.
When all life on the earth cannot survive, it also means that the last trace of life on the earth will come to an end, and the sun will once again become an ordinary star.
III. Conclusion.
Taking pictures of the earth, human science and technology have become more and more advanced, which not only allows human beings to understand the earth more and more, but also allows human beings to further observe other planets.
Humans are also expected to have more life planets in the future, but unlike Earth, they are planets that humans cannot live on.
The earth is also facing a huge crisis in the universe, and human beings cannot always rely on the earth's resources to survive, and they must also develop and explore space in the future.
Until the sun is no longer suitable for life, human beings should also cherish the relatively stable global environment, and at the same time prepare for the development of human civilization in the future.
We have a lot of time and a lot of time to explore the universe and find a new home suitable for human survival, which is also the goal of future human development in the future, and also the direction of future scientific and technological development.
Extended perspective
The earth is also an island in the universe, and with the continuous change of the sun, the earth also has the possibility of losing the environment, which also means that life on the earth will come to an end.
Human beings must cherish and learn to let go, so as to continue to move forward until the emergence of a new planet of life, which also opens up new scientific and technological development and exploration for human beings and contributes to the development of human civilization.
From the point of view of the formation of the three planets, all three planets were created behind the same cloud balloon, and there is a large gap in space between Venus and the Earth.
Mars, Venus, and Earth's oceans all eventually disappeared, while Earth retained the sea, so Earth's oceans are arguably the most precious.
But humans should not rely on marine life on Earth, and exploration from space has not found a star similar to Earth.
There are countless planets in space, but there is a huge difference between them and the earth, and they are all unsuitable for human existence.
In the future, human beings are expected to develop new technologies, so that they can explore farther into space, so as to find new homes, explore new continents, and explore new fields of science and technology, so as to inject new energy into human survival skills.