How did humans measure the diameter of the Milky Way, which is 200000 light-years?

Perhaps the most wonderful gift God has given humanity is to lift their heads and see the most mysterious thing in the world - the sky.. We can romantically believe that it is precisely because we see the sky that humans become curious about the world and take the first step towards change.

In ancient times, even if people wanted to explore the mysteries of the universe, there were no instruments or theories to discover what truly existed in the universe.. Under various limitations, the significance of human observation of the universe is limited to observing stars and predicting the future.

In modern times, our understanding of the universe has taken a big step forward.. With telescopes, humans can finally know what the world inside looks like.

With astronomy, humanity finally knows what the vast stars in the universe look like.. It can be said that exploring the history of the starry sky is the development of human intelligence.. The motivation to explore the starry sky is the crystallization of all human wisdom.

Over the years, our understanding of the universe has increased.

Now, we can finally know that the vast and boundless Milky Way above our heads is not actually an image of a river, its area is even more astonishing.. But there is another issue with curiosity: we cannot observe the Milky Way from within. So, how do we measure the diameter of the Milky Way galaxy?

Now, let's answer this question.

Measurement method.

It is certainly impossible to measure the diameter of the Milky Way using ordinary methods.

A very simple example, as we all know, the speed of light is fixed and unchanging. Some of you may wonder if it's possible to emit a beam of light and observe how it moves in the universe and when it will reach the boundary of the Milky Way.

In addition, there is also a brain teaser, which is to send an instrument outside the Milky Way to collect information from the instrument, in order to understand the diameter of the galaxy.

This kind of imaginative idea is naturally unrealistic. The best instrument for measuring the universe is a combination of mathematical methods and physical theories. In fact, our method of measuring the Milky Way is as follows: combining physical phenomena, using mathematical tools to calculate, and then obtaining a universal result.

In science, there are three methods for measuring distance.

The first method is called triangulation.

The second one is the measurement of Cepheid variables.

The third spectral parallax.

Among these three methods, the first method is the earliest and most widely used.. As early as ancient Greece, the mathematical festival Eratosthenes used this method to determine the approximate radius of the Earth.

This method can be said to be quite simple and practical. Apart from requiring a large amount of calculations, it does not require any advanced theories or instruments, so that the approximate radius of celestial bodies can be calculated.

However, this method also has its drawbacks. If it is a near Earth object, it is still possible, but for distant objects, this method is not very helpful.. If you want to measure the radius of the Milky Way using this method, it's too crazy.

So, how did scientists solve this problem?.

Measurement of the Milky Way Galaxy.

In practice, scientists have discovered a labor-saving method. This is a measurement of Cepheid variables.. As the name suggests, Cepheid variables are a special type of celestial body. This celestial body emits periodic light. In this way, observation also has reference significance.

The only drawback of this method is that it requires a lot of observation and cannot be achieved without advanced instruments. What scientists do is start with Cepheid variables, and then they start pushing it out a bit. After this process, the approximate range of the Milky Way can be calculated.

The radius of the Milky Way is an astonishing 200000 light-years. What is this concept?

If humans were technologically insane enough to travel at the speed of light, it would take 200000 years to cross the Milky Way.

This can only happen in science fiction novels.. According to the current level of human technology, this is not a fantasy, it is simply impossible for myths to achieve. Sun Wukong is too outrageous. It is estimated that it will take tens of thousands of years to complete a somersault in space.

After the second method, let's take a look at the third method.

Actually, the third method is similar to the second method. Scientists have drawn a map of the brightness of the Earth, which is divided into several levels. Then the scientists combined the planet's light with the map. If the pairing is successful, we can know the approximate distance of the planets.

This method may seem simple, but it is far more complex than the last two methods.. In addition to controlling work, scientists also apply a large amount of mathematical knowledge.

In this situation, the investment of money and energy is immeasurable. We have put in so much effort just to enhance our understanding of the sky above us and promote our own progress.

Postscript

Human exploration of the universe is destined to be endless.. This exploration will continue until the end of humanity.. Life on Earth is limited, and the universe is not only a mysterious representation of humanity, but also the direction of the future. Without the courage to step out of Earth and enter space, the future of humanity is bleak.

Exploring the infinite mysteries of the universe with limited human life is destined to be a difficult battle. But human courage is the most precious thing.

Without this courage, humanity is destined to be unable to develop in the long term.. For the future, we should maintain curiosity and awe towards the universe. Only in this way can we go further.