Over the past century, astronomers have improved their understanding of star formation and evolution.. That is, scientists have a good understanding of how stars change during their lives.. But comparing current models of stellar evolution with the evolution of the Sun reveals something of a mystery. Scientists believe that at the beginning of its life history, when the Earth first appeared, the Sun released much less energy and heat than it does now. This means that billions of years ago the water on the surface of our planet should have frozen and thus life could not have arisen.. As we see this did not happen. This is called the weak young Sun paradox and scientists have as many possible solutions as possible, writes IFLScience.

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The Sun emerged as a protostar from a gas cloud approximately 4.6 billion years ago.. And about 4.57 billion years ago, it turned into a full-fledged yellow dwarf star after thermonuclear fusion of hydrogen was launched in the core. The Earth, like the other planets in the solar system, emerged approximately 4.5 billion years ago from a cloud of gas and dust surrounding the young Sun..

As studies showed back in the 70s of the last century, 4.5-4 billion years ago the Sun released approximately 30% less energy and heat than now. Thus, the climate on our planet should have been very cold at that time, and all the water should have frozen, which would not have allowed life to arise on Earth.

As studies show, given the very low temperature on the surface of the Sun billions of years ago, which was approximately 2350 degrees Celsius (now approximately 5500 degrees Celsius), on Earth the average temperature should have been minus 28 degrees Celsius.

Yet studies of the oldest rocks around the world show that more than 3 billion years ago, the Earth had plenty of liquid water and a humid, warm climate.. Scientists also discovered fossils of the first living organisms.

The Earth was supposed to become like a large lifeless snow globe flying around the Sun, but this did not happen. For several decades now, scientists have been proposing different solutions to the faint young Sun paradox.. Among them are the following:.

As a reminder, Mars also shows signs that it had liquid water on the surface as early as 3.6 billion years ago, and also had a humid and warm climate, although it is now a very cold planet.

Scientists believe that Mars had such a climate, perhaps due to the greenhouse effect. To find out exactly what happened to Mars, you need to study its rocks in more detail, and for this they need to be delivered to Earth. But so far NASA does not have an exact plan on how to do this.. Focus has already written more about this.

Focus also wrote that Jeff Bezos' New Glenn rocket flew into space for the first time, but not everything went well. Elon Musk's Falcon-9 rocket has a serious 98-meter competitor.