The sun's surface is 5,500 degrees, Venus is sunburned into the "pressure cooker", why space is extremely cold?

When it comes to the night sky, what comes to mind must be the bright and shining stars on a black background. To the naked eye, there may be few stars in a certain direction, but as long as the telescope exposure for some time will be able to find that the seemingly sparse area of stars hidden dreamy and magnificent prosperous scene.

I think we all know that every star we see with the naked eye is the same as the sun can emit light to the stars, they emit light to reach the Earth, and to our eyes, we can see their existence.

Because of the stars and the high temperatures and bright light they emit, "the universe is hot" is the first impression many people have of it.

The scary temperature of celestial bodies

The stars in the universe are so hot that the word "hot" is not enough to describe their temperature. Take our Sun, a yellow dwarf star with spectral type G. Its surface temperature is about 5,200 degrees Celsius, and its inner core temperature is about 15 million degrees.

Although more than 10 million degrees is unimaginable, this is not the highest temperature of the star, there are many stars with extremely higher temperatures than the sun, for example, the surface temperature of Vega is almost twice as high as the sun, reaching about 9500 ℃.

Of course, this is far from the limit of stellar temperature. In Sagittarius there is a star codenamed "WR 102", its surface temperature has reached a staggering 200,000 ℃, a full 36 times the surface temperature of the Sun.

200,000 ℃ is the highest temperature of human discovery of the star, but from the highest temperature of the object there is still a very big gap because according to scientists' calculations, the surface temperature of the neutron star can reach 1.2 billion degrees, and its internal core temperature can reach the overturning perception of 10 billion degrees.

The temperature of neutron stars is exaggerated, but they are too far away from human beings, so we will not discuss it, we still put our attention and discussion point to the sun.

Because of the existence of the sun, we can feel the warmth of the sun on the earth, and many people do not know that, although the earth can feel the warmth of the sun, the vast space region between the earth and the sun the temperature is very low and even close to absolute zero.

According to scientists' calculations, the average temperature of the universe is only -270.4245 ℃.

May be used to the stars thousands or even hundreds of thousands of high temperatures, many people will think -270.4245 ℃ is nothing at all, at least it must be - thousands or hundreds of thousands of degrees Celsius to be considered low temperature, but in fact, -270.4245 ℃ has been very low.

Why?

We first need to know what the temperature is. In a broad sense, temperature refers to the speed or intensity of molecular motion, and the intensity is theoretically no upper limit (more than Planck temperature does not make sense for humans), so there will be tens of billions of high temperatures.

But it has a lower limit, the lower limit is when all molecules are at rest, that is, -273.15 ℃, which is often referred to as "absolute zero".

Like the speed of light, absolute zero is a theoretical value that can only be approached infinitely, but not reached. Because many particles do not have a rest mass, if this particle is "at rest", then it is the real sense of "disappear".

Daily life feels that simply lowering the temperature can not make something disappear, so from this point of view, we can well understand that absolute zero can never reach the characteristics.

Understanding the special nature of "absolute zero", we can know what kind of concept is -270.4245℃. It may not be as frightening as tens of billions of degrees, but from the point of view of extremes, it is not inferior to tens of billions of degrees of heat.

Back to the topic, the sun heated the Earth, and even directly Venus into a "pressure cooker", why the vast area of space is cold?

As just said, the nature of temperature is the movement of microscopic particles, so it needs a medium to show, so what medium in space can show the temperature? The answer is no. From the word "space" you should know that it means "nothing" in macroscopic terms.

Of course, although there is nothing in the macroscopic sense, space is not an absolute sense of "vacuum", there are still a lot of microscopic particles invisible to the naked eye, only that the density of these microscopic particles is extremely low, so low that it can not show the properties of temperature, which is the result of the space The "temperature" is close to absolute zero.

In addition, the extremely low density of the universe affects the transfer of stellar heat. For example, when the radiation is released from the sun high, its intensity is about 64 million watts per square meter, and when it travels through space to the Earth, the radiation intensity is only 1370 watts per square meter, which is 47,000 times lower than the initial intensity.

Note that such a violent energy decay occurs at a distance of only 0.000016 light years, and it can be seen that the decay will be even more violent at greater distances.

For example, 5.87 billion kilometers from the Sun, Pluto, the planet has been almost unaffected by any solar radiation, so its surface temperature is only 33 degrees Celsius higher than absolute zero.

It takes 5.46 hours for light to travel from the Sun to Pluto, which is very close compared to the distance of several light years between star systems, but even at such a close distance, the temperature is already so low that it is not surprising that the average temperature of the entire universe is -270.4245°C.

Is it true that Venus is a "pressure cooker" by the sun?

This statement is not accurate, because to be precise it is not "sun" into the pressure cooker, is "muffled" into the pressure cooker.

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Because there is no magnetic field protection, the violent solar wind will Venus's atmosphere ionization, so Venus lost all the water, and without water, the planet's carbon silicon can not be recycled, and volcanic eruption of large amounts of greenhouse gases - carbon dioxide.

Over time, Venus formed thousands of meters thick, the main component is the atmosphere of carbon dioxide, this thick atmosphere will be the solar radiation dead "muffled" in it, the temperature and pressure of Venus larger and larger, and finally formed today's cool "pressure cooker" of the surface environment.