How do we know the age of the Solar System?

*This text was written by a columnist. TecMundo; finally learn more.

this Milky WayThe galaxy that contains us and all the stars we can see in the night sky is almost as old as the Universe itself. Billions of years ago, in a distant region of one of the arms forming its spiral structure, a vast, cold molecular cloud was relatively isolated. Over time, this cloud condensed due to gravity and began to have a large concentration of material in the central region, which was surrounded by a pro-planet disk.

In this scenario, eventually, our Sun lit up and eight planets – Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune – along with other rocky bodies. solar system created.

Scientists currently claim that the Solar System is about 4.6 billion years old (4.57 billion years old for more curious minds with precision) and a relatively low uncertainty of plus or minus a few million years. But how do we know this? How is it possible to get an accurate value of such a distant time when Earth was nothing but a large, incandescent and extremely violent sphere?

The answer to this question is, as for many, Science. Over the past 100 years, humanity has learned a lot about the history of our Solar System and has since come to better understand how it came to be and how it has evolved.

As is common in astronomy, it is practically impossible to follow the evolution of many individual celestial bodies, such as galaxies, stars and planets. Because even if we add tens of generations to this calculation, the lifespan of a human being is much shorter than that of an astronomical object for obvious reasons.

Fortunately, the Universe is a huge place and presents a wide variety of situations and scenarios to our eyes. We’ve learned a lot by observing the formation of other stars, studying the distant regions that formed them, analyzing and measuring preplanetary disks, and many more.

• Also read: What do we know about the giants of the solar system?

In other words, observing stars at different stages of evolution makes it possible to piece together the puzzle of their history and understand how they came to be in our own Solar System.

But that’s definitely not all. Assuming the age of the Solar System is a few billion years, it is possible to get an accurate estimate by looking for elements with isotopes (i.e. atoms of the same chemical element with different amounts of neutrons). billions of years of lives.

Over time, these isotopes will decay through radioactive processes, and from observing the ratios of these decay products to the remaining starting material it is possible to determine how much time has passed since these objects formed. The most reliable elements for this are uranium and thorium.

But where is it possible to find the best conditions to carry out this type of analysis? This answer is in heaven. Well, at least it was: Studies of meteorites found on the Earth’s surface and considered the oldest material around us within reach of our hands are the best indicator for estimating the age of the Solar System.

The scientists analyzed a large number of meteorites that came to Earth, measured their isotopic abundances, and came to the surprising conclusion that they all formed more or less simultaneously (with some minor differences compared to astronomical time scales). The Solar System is about 4.57 billion years old.

Another way to get this estimate is to analyze moon rocks brought to Earth during space missions that haven’t been subjected to the same geological treatment as Earth’s rocks. This estimate results in a slightly lower value: about 4.51 billion years.

In summary, we can say with satisfactory confidence that the oldest solid matter we know of in the Solar System is about 4.57 billion years old. The Earth and Moon were probably about 50 to 65 million years younger, reaching their final form a little later. The Sun, by contrast, is perhaps slightly older, since its formation must have reached tens of millions of years, possibly 4.6 billion years, before the objects that make up the other components of the Solar System.

The key to ever-increasing accuracy in this age is to continue analyzing the sky and what comes from it, no matter what.

Nicolas Oliveiracolumnist TecMundoHe holds a bachelor’s degree in Physics and a master’s degree in Astrophysics. Professor and currently doing his PhD working with galaxy clusters at the National Observatory. He has experience in Teaching Physics and Astronomy and researching Extragalactic Astrophysics and Cosmology. He works as a scientific dissector and communicator for the dissemination and democratization of science. Nicolas is found on social networks as: @nicooliveira_.