Other planets
To be honest, the high activity of discussing the first post came as some surprise. A pleasant surprise, which is already there. Genuine interest, a large number of constructive comments and additions, the most different points of view regarding the issues raised in that post showed that similar topics are really close to the Habr community. Therefore, I decided to continue the “space” direction in this blog of today's article.
In almost every science fiction film, which takes place in a distant cosmos, we are somehow shown how the other planets look. Alas, these diverse and picturesque pictures are the product of the imagination of artists and designers. Until recently, mankind has not been able to not only consider the details, but at least understand the general color of the planets rotating in other stellar systems. The problem is that even the most advanced telescopes located in orbits around the Earth and not subject to distortions introduced by its atmosphere are not able to give a sufficiently detailed image of exoplanets (this is the name for any planet outside the solar system). This is due to the fact that compared with the stars the planets have a catastrophically low brightness and are physically many times smaller.
Due to the fact that stars simply eclipse the planets revolving around them with their light, scientists usually determine the very existence of these planets by indirect signs. For example, for short-term weak changes in the spectral composition of a star, when the planet passes between its luminary and observers.
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In 63 light-years from the old Earth, in the constellation Vulpecula, there is a small star about ÂĽ smaller than the Sun, with a sweet name HD 189773. A gas planet revolves around it, discovered in 2007 and named equally witty: HD 189773b. Its existence was discovered by the passage of a star against the background of a disk. Being one of the closest known exoplanets to us, HD 189773b has deserved the honor of being the first to appear, so to speak, in its true form. Such gas planets, comparable in size to Jupiter and rotating at a fairly short distance from their stars, astronomers called hot Jupiters . According to scientists, the planets of this type should be quite common in the universe.
To determine the color of the planet, astronomers had to firstseparate the flies from cutlets to clear the spectrum of light reflected by the planet from the spectrum of the star itself. To do this, using the spectrograph of the Hubble orbital telescope (Hubble) scanned this stellar system before, during and after the passage of the planet against the background of a star. This was made possible thanks to the successful location of the orbital plane. The brightness of HD 189773b is approximately 0.0001 times the brightness of its parent star. After analyzing the spectral composition of radiation in these three cases and the albedo of the planet, the scientists found that HD 189773b has an azure blue color. Something from the cosmos she looks like a pale blue dot . However, the similarity ends there. In our case, the blue color is due to the presence of water in the atmosphere and on the surface of the planet. In contrast to the cozy Earth, HD 189773b can be called one of the branches of hell. Judge for yourself:
So, returning to the subject of the article, the blue color of this sweet planet is due to the fact that its atmosphere is filled with dust from silicon compounds, that is, glass. By the way, all this horror should, according to scientists, be brightened with beautiful purple sunsets ...
Alas, so far this is the first and only study of this kind. Despite the fact that astronomers now know a little less than 900 exoplanets, their colors are still unknown to us. There are various reasons for this, among which the limited capabilities of observation devices do not always play the main role. Take, for example, the closest star system to us is Alpha Centauri. It is located only 4.4 light years from the Sun, and not in 63, as HD 189773. Due to its proximity to us and sufficient brightness, Alpha Centauri has been the object of astronomers for centuries. But only last year a planet was discovered in this star system. It turns out that all this time she was impossible to detect due to the fact that she is too close to her star. As a result, the star's radiation is so much higher than the intensity of light reflected by the planet that it took 4 years of continuous observations using the HARPS spectrograph , specially created for the most subtle measurements to search for exoplanets, to detect it. Proximity to the star is also the reason that the temperature on the surface of this planet reaches 1200 degrees Celsius.
Today our information about exoplanets is extremely insignificant. The number of stars in our Milky Way galaxy alone is approximately estimated at 100-400 billion. Recent studies suggest that theaverage temperature in a hospital is, on average, 1.6 planets per star, so potentially there are approximately 500 billion planets in the Milky Way. True, as can be seen from the two examples above, not all the planets are “equally useful” from a practical point of view. Today it is believed that the number of potentially habitable planets in our galaxy can reach 17 billion (in this place all ufologists exhale together).
It must be said that it is not always possible to establish the reason why a celestial body has a particular color. For examples do not need to go to other constellations: scientists still can not clearly say why Jupiter and Venus have just such a color.
Of course, scientists have put forward a number of hypotheses, but the composition of the clouds covering the whole area of ​​Venus is not known until now, even despite the unique Soviet program of research of this planet. The origin of the colors of the rest of the planets in the solar system is generally well known to scientists. Perhaps aesthetically the most interesting can be called Mars and Neptune. And if the appearance of the “red planet” has already become a hackneyed stamp, then the farthest planet received the name of the god of the seas for nothing: ultramarine color of the planet is mainly given by methane vapor in the outer layers of the atmosphere.
Since we are still formally alone in the Universe, today the only celestial body whose color is determined not only by the chemical composition of the atmosphere and surface is the Earth. To a great extent, the beauty of our house is given by the green color of vegetation . Almost a quarter of our planet’s area is covered by the Kingdom of Chlorophyll . Its value for us and all of our planet is known to everyone. Given the uncontrolled growth of the population, before humanity are increasingly looming lack of oil and gas, and food and drinking water. And the most crowded places on the planet, Africa, India and China, find themselves in quite an unenviable position. The wars of the future are likely to be called "water" wars. But this is a topic for a completely different article.
In almost every science fiction film, which takes place in a distant cosmos, we are somehow shown how the other planets look. Alas, these diverse and picturesque pictures are the product of the imagination of artists and designers. Until recently, mankind has not been able to not only consider the details, but at least understand the general color of the planets rotating in other stellar systems. The problem is that even the most advanced telescopes located in orbits around the Earth and not subject to distortions introduced by its atmosphere are not able to give a sufficiently detailed image of exoplanets (this is the name for any planet outside the solar system). This is due to the fact that compared with the stars the planets have a catastrophically low brightness and are physically many times smaller.
Due to the fact that stars simply eclipse the planets revolving around them with their light, scientists usually determine the very existence of these planets by indirect signs. For example, for short-term weak changes in the spectral composition of a star, when the planet passes between its luminary and observers.
')
In 63 light-years from the old Earth, in the constellation Vulpecula, there is a small star about ÂĽ smaller than the Sun, with a sweet name HD 189773. A gas planet revolves around it, discovered in 2007 and named equally witty: HD 189773b. Its existence was discovered by the passage of a star against the background of a disk. Being one of the closest known exoplanets to us, HD 189773b has deserved the honor of being the first to appear, so to speak, in its true form. Such gas planets, comparable in size to Jupiter and rotating at a fairly short distance from their stars, astronomers called hot Jupiters . According to scientists, the planets of this type should be quite common in the universe.
To determine the color of the planet, astronomers had to first
- The planet is a gas giant like our Jupiter.
- Because of its proximity to its star, the surface temperature of HD 189773b is 1000 degrees Celsius, and the temperature difference between the day and night sides reaches 260 degrees.
- A dense foggy atmosphere about 1000 km thick (the atmosphere of the Earth is 120 km thick) boils with huge turbulences with winds blowing at a speed of 7000 km / hour. For comparison, the most powerful typhoon recorded in the history of mankind - Type 1979 — reached a speed of 300 km / h.
- The mist itself, which fills the atmosphere of the planet, consists of the smallest (less than 0.001 mm) iron particles, silicon compounds, and aluminum oxide, of which sapphires form on Earth.
- All this is subjected to a powerful stream of ultraviolet radiation, which is 20 times higher than the "earth" level. And the X-rays falling on HD 189773b are 3 million (!) Times higher than on Earth.
So, returning to the subject of the article, the blue color of this sweet planet is due to the fact that its atmosphere is filled with dust from silicon compounds, that is, glass. By the way, all this horror should, according to scientists, be brightened with beautiful purple sunsets ...
Who else?
Alas, so far this is the first and only study of this kind. Despite the fact that astronomers now know a little less than 900 exoplanets, their colors are still unknown to us. There are various reasons for this, among which the limited capabilities of observation devices do not always play the main role. Take, for example, the closest star system to us is Alpha Centauri. It is located only 4.4 light years from the Sun, and not in 63, as HD 189773. Due to its proximity to us and sufficient brightness, Alpha Centauri has been the object of astronomers for centuries. But only last year a planet was discovered in this star system. It turns out that all this time she was impossible to detect due to the fact that she is too close to her star. As a result, the star's radiation is so much higher than the intensity of light reflected by the planet that it took 4 years of continuous observations using the HARPS spectrograph , specially created for the most subtle measurements to search for exoplanets, to detect it. Proximity to the star is also the reason that the temperature on the surface of this planet reaches 1200 degrees Celsius.
Today our information about exoplanets is extremely insignificant. The number of stars in our Milky Way galaxy alone is approximately estimated at 100-400 billion. Recent studies suggest that the
solar system
It must be said that it is not always possible to establish the reason why a celestial body has a particular color. For examples do not need to go to other constellations: scientists still can not clearly say why Jupiter and Venus have just such a color.
Of course, scientists have put forward a number of hypotheses, but the composition of the clouds covering the whole area of ​​Venus is not known until now, even despite the unique Soviet program of research of this planet. The origin of the colors of the rest of the planets in the solar system is generally well known to scientists. Perhaps aesthetically the most interesting can be called Mars and Neptune. And if the appearance of the “red planet” has already become a hackneyed stamp, then the farthest planet received the name of the god of the seas for nothing: ultramarine color of the planet is mainly given by methane vapor in the outer layers of the atmosphere.
Earth in the porthole
Since we are still formally alone in the Universe, today the only celestial body whose color is determined not only by the chemical composition of the atmosphere and surface is the Earth. To a great extent, the beauty of our house is given by the green color of vegetation . Almost a quarter of our planet’s area is covered by the Kingdom of Chlorophyll . Its value for us and all of our planet is known to everyone. Given the uncontrolled growth of the population, before humanity are increasingly looming lack of oil and gas, and food and drinking water. And the most crowded places on the planet, Africa, India and China, find themselves in quite an unenviable position. The wars of the future are likely to be called "water" wars. But this is a topic for a completely different article.
Source: https://habr.com/ru/post/191274/
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