4.6 billion years ago, clumps began to form in our Galaxy from clouds of stellar matter. Increasingly, more compacted and thickened, the gases heated up, radiating heat. With increasing density and temperature, nuclear reactions began, turning hydrogen into helium. Thus, there was a very powerful source of energy - the Sun.

Simultaneously with the increase in the temperature and volume of the Sun, as a result of the union of fragments of interstellar dust in a plane perpendicular to the axis of rotation of the Star, planets and their satellites were created. The formation of the solar system was completed about 4 billion years ago.

The solar system currently has eight planets. These are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Nepto. Pluto is a dwarf planet, the largest known Kuiper belt object (it is a large fragment belt similar to the asteroid belt). After its discovery in 1930, it was considered the ninth planet. The situation changed in 2006 with the adoption of a formal definition of the planet.

On the planet closest to the Sun, Mercury, it never rains. This is due to the fact that the atmosphere of the planet is so rarefied that it is simply impossible to fix it. And where can rain come from, if the daytime temperature on the surface of the planet sometimes reaches 430º Celsius. Yeah, I wouldn't want to be there :)

But on Venus, acid rains constantly occur, since the clouds above this planet are not made of life-giving water, but of deadly sulfuric acid. True, since the temperature on the surface of the third planet reaches 480º Celsius, the drops of acid evaporate before they reach the planet. The sky above Venus is pierced by large and terrible lightning, but there is more light and roar from them than rain.

On Mars, according to scientists, a long time ago, natural conditions were the same as on Earth. Billions of years ago, the atmosphere above the planet was much denser, and it is possible that abundant rains filled these rivers. But now the planet has a very rarefied atmosphere, and photographs transmitted by reconnaissance satellites indicate that the surface of the planet resembles the deserts of the southwestern United States or the Dry Valleys in Antarctica. When part of Mars is shrouded in winter, thin clouds containing carbon dioxide appear over the red planet, and frost covers dead rocks. In the early morning in the valleys there are such thick fogs that it seems that it is about to rain, but such expectations are in vain.

By the way, the air temperature during the day on Mrse is 20º Celsius. True, at night it can drop to -140 :(

Jupiter is the largest of the planets and is a giant ball of gas! This ball is composed almost entirely of helium and hydrogen, but it is possible that deep inside the planet is a small solid core, shrouded in an ocean of liquid hydrogen. However, Jupiter is surrounded on all sides by colored bands of clouds. Some of these clouds even consist of water, but, as a rule, the vast majority of them form solidified ammonia crystals. From time to time, the strongest hurricanes and storms fly over the planet, bringing snowfalls and rains of ammonia. That's where to hold the Magic Flower.

A. Mikhailov, prof.

Science and life // Illustrations

Lunar landscape.

Melting polar spot on Mars.

Orbits of Mars and Earth.

Lowell's map of Mars.

Kuhl's model of Mars.

Drawing of Mars by Antoniadi.

Considering the question of the existence of life on other planets, we will only talk about the planets of our solar system, since we do not know anything about the presence of other suns, which are stars, of their own planetary systems similar to ours. According to modern views on the origin of the solar system, it can even be assumed that the formation of planets revolving around a central star is an event, the probability of which is negligible, and that therefore the vast majority of stars do not have their own planetary systems.

Further, it is necessary to make a reservation that we involuntarily consider the question of life on the planets from our earthly point of view, assuming that this life manifests itself in the same forms as on Earth, i.e., assuming life processes and the general structure of organisms similar to earthly ones. In this case, for the development of life on the surface of a planet, certain physico-chemical conditions must exist, the temperature must not be too high and not too low, the presence of water and oxygen must be present, and carbon compounds must be the basis of organic matter.

planetary atmospheres

The presence of an atmosphere on planets is determined by the stress of gravity on their surface. Large planets have enough gravitational force to keep a gaseous shell around them. Indeed, gas molecules are in constant rapid motion, the speed of which is determined by the chemical nature of this gas and temperature.

Light gases, hydrogen and helium, have the highest speed; as the temperature rises, the speed increases. Under normal conditions, i.e., a temperature of 0 ° and atmospheric pressure, the average speed of a hydrogen molecule is 1840 m / s, and oxygen 460 m / s. But under the influence of mutual collisions, individual molecules acquire velocities that are several times higher than the indicated average numbers. If a hydrogen molecule appears in the upper layers of the earth's atmosphere with a speed exceeding 11 km / s, then such a molecule will fly away from the Earth into interplanetary space, since the force of gravity will be insufficient to hold it.

The smaller the planet, the less massive it is, the less this limiting or, as they say, critical speed. For the Earth, the critical speed is 11 km/s, for Mercury it is only 3.6 km/s, for Mars 5 km/s, for Jupiter, the largest and most massive of all planets, it is 60 km/s. It follows from this that Mercury, and even more so even smaller bodies, like planetary satellites (including our Moon) and all small planets (asteroids), cannot keep the atmospheric shell near their surface with their weak attraction. Mars is able, albeit with difficulty, to hold an atmosphere much thinner than Earth's, but as for Jupiter, Saturn, Uranus, and Neptune, their attraction is strong enough to hold powerful atmospheres containing light gases, such as ammonia. and methane, and possibly also free hydrogen.

The absence of an atmosphere inevitably entails the absence of liquid water. In airless space, the evaporation of water occurs much more vigorously than at atmospheric pressure; therefore, water quickly turns into vapor, which is a very light basin, subject to the same fate as other gases of the atmosphere, i.e., it leaves the surface of the planet more or less quickly.

It is clear that on a planet devoid of atmosphere and water, the conditions for the development of life are completely unfavorable, and we cannot expect either plant or animal life on such a planet. All small planets, satellites of planets, and from large planets - Mercury fall under this category. Let's say a little more about the two bodies of this category, namely the Moon and Mercury.

Moon and Mercury

For these bodies, the absence of an atmosphere has been established not only by the above considerations, but also by direct observations. When the Moon moves across the sky, making its way around the Earth, it often covers the stars. The disappearance of a star behind the disk of the Moon can be observed even through a small tube, and it always happens quite instantly. If the lunar paradise were surrounded by at least a rare atmosphere, then, before completely disappearing, the star would shine for some time through this atmosphere, and the apparent brightness of the star would gradually decrease, in addition, due to the refraction of light, the star would seem displaced from its place . All these phenomena are completely absent when the stars are covered by the Moon.

Lunar landscapes observed through telescopes amaze with the sharpness and contrast of their illumination. There are no penumbra on the Moon. There are deep black shadows next to bright, sunlit places. This happens because, due to the absence of an atmosphere on the Moon, there is no blue daytime sky, which would soften the shadows with its light; the sky is always black. There is no twilight on the Moon, and after sunset, a dark night immediately sets in.

Mercury is farther from us than the Moon. Therefore, we cannot observe such details as on the Moon. We do not know the type of its landscape. The occultation of stars by Mercury, due to its apparent smallness, is extremely rare, and there is no indication that such occultations have ever been observed. But there are passages of Mercury in front of the solar disk, when we observe that this planet in the form of a tiny black dot slowly creeps over the bright solar surface. In this case, the edge of Mercury is sharply delineated, and those phenomena that were seen during the passage of Venus in front of the Sun were not observed in Mercury. But it is still possible that small traces of the atmosphere around Mercury have been preserved, but this atmosphere has a completely negligible density compared to the earth.

On the Moon and Mercury, temperature conditions are completely unfavorable for life. The moon rotates extremely slowly around its axis, due to which day and night continue on it for fourteen days. The heat of the sun's rays is not moderated by the air envelope, and as a result, during the day on the Moon, the surface temperature rises to 120 °, i.e., above the boiling point of water. During the long night the temperature drops to 150° below zero.

During a lunar eclipse, it was observed how, in just over an hour, the temperature dropped from 70 ° warm to 80 ° below zero, and after the end of the eclipse, almost in the same short time, returned to its original value. This observation points to the extremely low thermal conductivity of the rocks that form the lunar surface. Solar heat does not penetrate deep into, but remains in the thinnest upper layer.

One must think that the surface of the Moon is covered with light and loose volcanic tuffs, maybe even ash. Already at a depth of a meter, the contrasts of heat and cold are smoothed out “so much so that it is likely that an average temperature prevails there, which differs little from the average temperature of the earth's surface, i.e., a few degrees above zero. It may be that some embryos of living matter have been preserved there, but their fate, of course, is unenviable.

On Mercury, the difference in temperature conditions is even sharper. This planet always faces the Sun on one side. On the daytime hemisphere of Mercury, the temperature reaches 400 °, i.e., it is above the melting point of lead. And on the night hemisphere, frost should reach the temperature of liquid air, and if there was an atmosphere on Mercury, then on the night side it should turn into liquid, and maybe even freeze. Only on the border between the day and night hemispheres within a narrow zone can there be temperature conditions that are at least somewhat favorable for life. However, there is no reason to think about the possibility of developed organic life there. Further, in the presence of traces of the atmosphere, free oxygen could not be retained in it, since at the temperature of the daytime hemisphere, oxygen vigorously combines with most chemical elements.

So, with regard to the possibility of life on the Moon, the prospects are rather unfavorable.

Venus

Unlike Mercury, Venus has certain signs of a thick atmosphere. When Venus passes between the Sun and the Earth, it is surrounded by a light ring - this is its atmosphere, which is illuminated by the Sun in the light. Such passages of Venus in front of the solar disk are very rare: the last passage took place in 18S2, the next one will occur in 2004. However, almost every year Venus passes, although not through the solar disk itself, but close enough to it, and then it is visible in the form of a very narrow sickle, like the moon immediately after the new moon. According to the laws of perspective, the crescent of Venus illuminated by the Sun should make an arc of exactly 180 °, but in reality a longer bright arc is observed, which occurs due to the reflection and bending of the sun's rays in the atmosphere of Venus. In other words, there is twilight on Venus, which increases the length of the day and partially illuminates its night hemisphere.

The composition of the atmosphere of Venus is still poorly understood. In 1932, with the help of spectral analysis, the presence of a large amount of carbon dioxide was detected in it, corresponding to a layer with a thickness of 3 km under standard conditions (i.e., at 0 ° and 760 mm pressure).

The surface of Venus always appears to us as dazzlingly white and without noticeable permanent spots or outlines. It is believed that in the atmosphere of Venus there is always a thick layer of white clouds, completely covering the solid surface of the planet.

The composition of these clouds is unknown, but most likely they are water vapor. What is under them, we do not see, but it is clear that the clouds must moderate the heat of the sun's rays, which on Venus, which is closer to the Sun than the Earth, would otherwise be excessively strong.

Temperature measurements gave about 50-60° heat for the day hemisphere, and 20° frost for the night. Such contrasts are explained by the slow rotation of Venus around the axis. Although the exact period of its rotation is unknown due to the absence of noticeable spots on the surface of the planet, but, apparently, the day continues on Venus no less than our 15 days.

What are the chances of life on Venus?

Scholars differ on this point. Some believe that all the oxygen in its atmosphere is chemically bound and exists only as part of carbon dioxide. Since this gas has a low thermal conductivity, in this case the temperature near the surface of Venus should be quite high, perhaps even close to the boiling point of water. This could explain the presence of a large amount of water vapor in the upper layers of its atmosphere.

Note that the above results of determining the temperature of Venus refer to the outer surface of the cloud cover, i.e. to a fairly high altitude above its solid surface. In any case, one must think that the conditions on Venus are reminiscent of a greenhouse or conservatory, but probably with a much higher temperature.

Mars

The greatest interest from the point of view of the question of the existence of life is the planet Mars. In many ways, it is similar to Earth. From the spots that are clearly visible on its surface, it has been established that Mars rotates about its axis, making one revolution in 24 hours and 37 meters. Therefore, there is a change of day and night on it of almost the same duration as on Earth.

The axis of rotation of Mars makes an angle of 66 ° with the plane of its orbit, almost exactly the same as that of the Earth. Due to this axial tilt on Earth, the seasons change. Obviously, on Mars there is the same change, but only every season on Earth is almost twice as long as ours. The reason for this is that Mars, being on average one and a half times farther from the Sun than the Earth, makes its revolution around the Sun in almost two Earth years, more precisely in 689 days.

The most distinct detail on the surface of Mars, noticeable when viewed through a telescope, is a white spot, which in its position coincides with one of its poles. The spot at the south pole of Mars is best seen, because during periods of its closest proximity to the Earth, Mars is tilted towards the Sun and the Earth with its southern hemisphere. It has been noticed that with the onset of winter in the corresponding hemisphere of Mars, the white spot begins to increase, and in summer it decreases. There were even cases (for example, in 1894) when the polar spot almost completely disappeared in autumn. One might think that this is snow or ice, which is deposited in winter as a thin cover near the poles of the planet. That this cover is very thin follows from the above observation of the disappearance of the white spot.

Due to the remoteness of Mars from the Sun, the temperature on it is relatively low. The summer there is very cold, and yet it happens that the polar snows completely melt. The long duration of summer does not adequately compensate for the lack of heat. It follows from this that little snow falls there, perhaps only a few centimeters, it is even possible that the white polar spots do not consist of snow, but of hoarfrost.

This circumstance is in full agreement with the fact that, according to all data, there is little moisture on Mars, little water. Seas and large water spaces were not found on it. Clouds are very rarely observed in its atmosphere. The very orange coloration of the planet's surface, due to which Mars appears to the naked eye as a red star (hence its name from the ancient Roman god of war), is explained by most "observers" by the fact that the surface of Mars is a waterless sandy desert, colored with iron oxides.

Mars moves around the Sun in a markedly elongated ellipse. Due to this, its distance from the Sun varies over a fairly wide range - from 206 to 249 million km. When the Earth is on the same side of the Sun as Mars, the so-called oppositions of Mars occur (because Mars at that time is on the opposite side of the sky from the Sun). During oppositions, Mars is observed in the night sky under favorable conditions. Oppositions alternate on average after 780 days, or after two years and two months.

However, not in every opposition, Mars approaches the Earth at its shortest distance. To do this, it is necessary that the opposition coincides with the time of the closest approach of Mars to the Sun, which happens only every seventh or eighth opposition, that is, after about fifteen years. Such oppositions are called great oppositions; they took place in 1877, 1892, 1909 and 1924. The next great confrontation will be in 1939. It is to these dates that the main observations of Mars and related discoveries are timed. Mars was closest to the Earth during the 1924 opposition, but even then its distance from us was 55 million km. Mars is never closer to Earth.

Channels on Mars

In 1877, the Italian astronomer Schiaparelli, making observations with a relatively modest telescope, but under the transparent sky of Italy, discovered on the surface of Mars, in addition to dark spots, albeit incorrectly called seas, a whole network of narrow straight lines or stripes, which he called the straits (canale in Italian). Hence the word "channel" began to be used in other languages ​​to refer to these mysterious formations.

Schiaparelli, as a result of his many years of observations, compiled a detailed map of the surface of Mars, on which hundreds of channels were drawn connecting the dark spots of the "seas" between the subs. Later, the American astronomer Lowell, who even built a special observatory in Arizona to observe Mars, discovered channels in the dark spaces of the "seas". He found that both the "seas" and the channels change their visibility depending on the seasons: in summer they become darker, sometimes taking on a gray-greenish tint; in winter they turn pale and become brownish. Lowell's maps are even more detailed than Schiaparelli's maps, they are marked with many channels that form a complex, but fairly regular geometric network.

To explain the phenomena observed on Mars, Lowell developed a theory that was widely accepted, mainly among amateur astronomers. This theory boils down to the following.

The orange surface of the planet Lowell, like most other observers, takes for a sandy wasteland. He considers the dark spots of the "seas" to be areas covered with vegetation - fields and forests. He considers the canals to be an irrigation network carried out by intelligent beings living on the surface of the planet. However, the channels themselves are not visible to us from the Earth, since their width is far from sufficient for this. To be visible from Earth, the channels must be at least tens of kilometers wide. Therefore, Lowell thinks that we see only a wide strip of vegetation, which unfolds its green leaves, when the channel itself, which lies in the middle of this strip, is filled with water in the spring, flowing from the poles, where it is formed from the melting of polar snows.

However, little by little, doubts began to arise about the reality of such straightforward channels. The most indicative was the fact that observers armed with the most powerful modern telescopes did not see any channels, but only observed an unusually rich picture of different details and shades on the surface of Mars, devoid, however, of regular geometric outlines. Only observers who used medium-strength instruments saw and sketched the channels. Hence, a strong suspicion arose that the channels represent only an optical illusion (an optical illusion) that occurs with extreme eye strain. A lot of work and various experiments have been carried out to clarify this circumstance.

The most convincing are the results obtained by the German physicist and physiologist Kühl. They arranged a special model depicting Mars. Against a dark background, Kühl pasted a circle he had cut out of an ordinary newspaper, on which were placed several gray spots, reminiscent of the outlines of the "seas" on Mars. If we consider such a model close up, then it is clearly visible what it is - you can read a newspaper text and no illusion is created. But if you move further away, then with the right lighting, straight thin stripes begin to appear, going from one dark spot to another and, moreover, not coinciding with lines of printed text.

Kuhl studied this phenomenon in detail.

He showed that three are the presence of many small details and shades, gradually turning into one another, when the eye cannot catch them “about all the details, there is a desire to combine these details with simpler geometric patterns, as a result of which the illusion of straight stripes appears where there are no correct outlines. The modern eminent observer Antoniadi, who is at the same time a good artist, paints Mars spotty, with a mass of irregular details, but without any rectilinear channels.

You might think that this issue is best solved by three photography assistance. A photographic plate cannot be deceived: it would seem that it should show what actually exists on Mars. Unfortunately, it is not. Photography, which, when applied to stars and nebulae, has given so much, in relation to the surface of the planets, gives less than what the eye of the observer sees with the same instrument. This is explained by the fact that the image of Mars, obtained even with the help of the largest and longest-focus instruments, on the plate turns out to be very small in size - only up to 2 mm in diameter. Of course, it is impossible to make out large details on such an image. In photographs, there is a defect from which modern photography enthusiasts who shoot with Leica-type devices suffer so much. Namely, the graininess of the image appears, which obscures all the small details.

Life on Mars

However, photographs of Mars, taken through different light filters, clearly proved the existence of an atmosphere on Mars, although much rarer than that of the Earth. Sometimes in the evening in this atmosphere bright points are noticed, which, probably, are cumulus clouds. But in general, the cloudiness on Mars is negligible, which is consistent with the small amount of water on it.

Nearly all observers of Mars now agree that the dark patches of the "seas" do indeed represent areas covered with plants. In this respect, Lowell's theory is confirmed. However, until relatively recently, there was one obstacle. The question was complicated by the temperature conditions on the surface of Mars.

Since Mars is one and a half times farther from the Sun than the Earth, it receives two and a quarter times less heat. The question of to what temperature such an insignificant amount of heat can warm its surface depends on the structure of the Martian atmosphere, which is a “fur coat” of thickness and composition unknown to us.

Recently it was possible to determine the surface temperature of Mars by direct measurements. It turned out that in the equatorial regions at noon the temperature rises to 15-25°C, but in the evening a strong cooling sets in, and the night, apparently, is accompanied by constant hard frosts.

Conditions on Mars are similar to those we have on high mountains: rarefied and transparent air, significant heating from direct sunlight, cold in the shade and severe night frosts. The conditions are no doubt very harsh, but it can be assumed that the plants have acclimatized, adapted to them, as well as to the lack of moisture.

So, the existence of plant life on Mars can be considered almost proven, but with regard to animals, and even more so intelligent ones, we cannot say anything definite yet.

As for the other planets of the solar system - Jupiter, Saturn, Uranus and Neptune, it is difficult to assume the possibility of life on them for the following reasons: firstly, low temperature due to the distance from the Sun and, secondly, poisonous gases recently discovered in their atmospheres - ammonia and methane. If these planets have a solid surface, then it is hidden somewhere at a great depth, while we see only the upper layers of their extremely powerful atmospheres.

Even less likely is life on the planet farthest from the Sun, the recently discovered Pluto, about whose physical conditions we still know nothing.

So, of all the planets in our solar system (except the Earth), one can suspect the existence of life on Venus and consider the existence of life on Mars almost proven. But, of course, this is all about the present. Over time, with the evolution of planets, conditions can change dramatically. We will not talk about this due to lack of data.

To the question And what planets of the solar system HAVE an atmosphere? What is its composition? given by the author . the best answer is The Sun, eight of the nine planets (except Mercury) and three of the sixty-three satellites have an atmosphere. Each atmosphere has its own special chemical composition and behavior called "weather". Atmospheres are divided into two groups: for terrestrial planets, the dense surface of the continents or the ocean determines the conditions at the lower boundary of the atmosphere, and for gas giants, the atmosphere is practically bottomless.
About the planets separately:
1. Mercury has practically no atmosphere - only an extremely rarefied helium shell with the density of the earth's atmosphere at an altitude of 200 km. Probably, helium is formed during the decay of radioactive elements in the bowels of the planet. Mercury has a weak magnetic field and no satellites.
2. The atmosphere of Venus consists mainly of carbon dioxide (CO2), as well as a small amount of nitrogen (N2) and water vapor (H2O). Hydrochloric acid (HCl) and hydrofluoric acid (HF) were found as small impurities. Surface pressure 90 bar (as in the earth's seas at a depth of 900 m); a temperature of about 750 K over the entire surface both day and night. The reason for such a high temperature near the surface of Venus is what is not quite accurately called the "greenhouse effect": the sun's rays pass relatively easily through the clouds of its atmosphere and heat the surface of the planet, but the thermal infrared radiation of the surface itself escapes through the atmosphere back into space with great difficulty.
3. The rarefied atmosphere of Mars consists of 95% carbon dioxide and 3% nitrogen. Water vapor, oxygen and argon are present in small quantities. The average pressure at the surface is 6 mbar (i.e., 0.6% of the earth's). At such a low pressure, there can be no liquid water. The average daily temperature is 240 K, and the maximum in summer at the equator reaches 290 K. Daily temperature fluctuations are about 100 K. Thus, the climate of Mars is the climate of a cold, dehydrated high-altitude desert.
4. A telescope on Jupiter shows cloud bands parallel to the equator; bright zones in them are interspersed with reddish belts. Probably, bright zones are areas of updrafts where the tops of ammonia clouds are visible; reddish belts are associated with downdrafts, the bright color of which is determined by ammonium hydrosulfate , as well as compounds of red phosphorus, sulfur, and organic polymers. In addition to hydrogen and helium, CH4, NH3, H2O, C2H2, C2H6, HCN, CO, CO2, PH3, and GeH4 have been spectroscopically detected in Jupiter's atmosphere.
5. In a telescope, the disk of Saturn does not look as spectacular as Jupiter: it has a brownish-orange color and weakly pronounced belts and zones. The reason is that the upper regions of its atmosphere are filled with light-scattering ammonia (NH3) fog. Saturn is farther from the Sun, therefore, the temperature of its upper atmosphere (90 K) is 35 K lower than that of Jupiter, and ammonia is in a condensed state. With depth, the temperature of the atmosphere increases by 1.2 K / km, so the cloud structure resembles that of Jupiter: under a cloud layer of ammonium hydrosulfate there is a layer of water clouds. In addition to hydrogen and helium, CH4, NH3, C2H2, C2H6, C3H4, C3H8, and PH3 have been spectroscopically detected in Saturn's atmosphere.
6. The atmosphere of Uranus contains mainly hydrogen, 12-15% helium and some other gases. The temperature of the atmosphere is about 50 K, although in the upper rarefied layers it rises to 750 K during the day and 100 K at night.
7. The Great Dark Spot and a complex system of vortex flows were discovered in the atmosphere of Neptune.
8. Pluto has a highly elongated and inclined orbit; at perihelion, it approaches the Sun at 29.6 AU and recedes at aphelion at 49.3 AU. Pluto passed perihelion in 1989; from 1979 to 1999 it was closer to the Sun than Neptune. However, due to the large inclination of Pluto's orbit, its path never intersects with Neptune. The average surface temperature of Pluto is 50 K, it changes from aphelion to perihelion by 15 K, which is quite noticeable at such low temperatures. In particular, this leads to the appearance of a rarefied methane atmosphere during the period of the planet's passage of perihelion, but its pressure is 100,000 times less than the pressure of the earth's atmosphere. Pluto cannot hold the atmosphere for a long time, because it is smaller than the moon.
Source: I didn’t write about the earth!))) You can’t see the earth through a telescope !!))

Answer from Egor Vedrov[newbie]
is on earth

Answer from Irina Serikova MADOU №21 Ivushka[active]
Pluto is no longer a planet

Answer from Belyaev V.N.[guru]
On Venus. Lots of carbon dioxide. On Saturn, too. There's a lot of methane in there. I don't remember Pluto.

Answer from Driver[guru]
The composition is complex, but air is only on Earth.

Answer from Earth orbit director[guru]
Mercury weak atm.
Venus is very powerful and dense
mars weak
Ganymede, Callisto, and Europa also have atmospheres.

Answer from Leka[guru]
Astrologer, you also need to copy-paste wisely and indicate the source ...)))
Although, it seems that the question was specifically intended for you ... well, it won’t get away from me.
Mercury has practically no atmosphere - only an extremely rarefied helium shell with the density of the earth's atmosphere at an altitude of 200 km. Probably, helium is formed during the decay of radioactive elements in the bowels of the planet. In addition, it is made up of atoms captured from the solar wind or knocked out by the solar wind from the surface - sodium, oxygen, potassium, argon, hydrogen.
The atmosphere of Venus is composed primarily of carbon dioxide (CO2) with small amounts of nitrogen (N2) and water vapor (H2O). Hydrochloric acid (HCl) and hydrofluoric acid (HF) were found as small impurities. The pressure at the surface is 90 bar (as in the Earth's seas at a depth of 900 m). The clouds of Venus are made up of microscopic droplets of concentrated sulfuric acid (H2SO4).
The rarefied atmosphere of Mars consists of 95% carbon dioxide and 3% nitrogen. Small amounts of water vapor, oxygen and argon are present. The average pressure at the surface is 6 mbar (i.e., 0.6% of the earth).
Jupiter's low average density (1.3 g/cm3) indicates a composition close to the Sun's: mostly hydrogen and helium.
A telescope on Jupiter shows cloud bands parallel to the equator; light zones in them are interspersed with reddish belts. It is likely that the light zones are areas of updrafts where the tops of ammonia clouds are visible; reddish belts are associated with downdrafts, the bright color of which is determined by ammonium hydrosulfate, as well as compounds of red phosphorus, sulfur and organic polymers. In addition to hydrogen and helium, CH4, NH3, H2O, C2H2, C2H6, HCN, CO, CO2, PH3, and GeH4 have been spectroscopically detected in Jupiter's atmosphere. At a depth of 60 km there should be a layer of water clouds.
Its satellite Io has an extremely rarefied atmosphere of sulfur dioxide (of volcanic origin) SO2.
The oxygen atmosphere of Europe is so rarefied that the pressure on the surface is one hundred billionth of that of the earth.
Saturn is also a hydrogen-helium planet, but the relative abundance of helium in Saturn is less than that of Jupiter; below and its average density. Its upper atmosphere is filled with light-scattering ammonia (NH3) fog. In addition to hydrogen and helium, CH4, C2H2, C2H6, C3H4, C3H8, and PH3 have been spectroscopically detected in Saturn's atmosphere.
Titan, the second largest moon in the solar system, is unique in that it has a persistent, powerful atmosphere composed mostly of nitrogen and a small amount of methane.
The atmosphere of Uranus contains mostly hydrogen, 12–15% helium, and a few other gases.
The spectrum of Neptune is also dominated by methane and hydrogen bands.
Pluto is no longer a planet...
And as a bonus:

Answer from Lyubov Kasperovich (Mashkova)[active]
There is nowhere else like it on Earth.

Answer from Ksenia Stepanova[newbie]
The atmosphere of Mercury is so rarefied that, one might say, it is practically non-existent. The air envelope of Venus consists of carbon dioxide (96%) and nitrogen (about 4%), it is very dense - the atmospheric pressure near the surface of the planet is almost 100 times greater than on Earth. The Martian atmosphere also consists mainly of carbon dioxide (95%) and nitrogen (2.7%), but its density is about 300 times less than that of the earth, and its pressure is almost 100 times less. The visible surface of Jupiter is actually the top layer of a hydrogen-helium atmosphere. The air shells of Saturn and Uranus are the same in composition. The beautiful blue color of Uranus is due to the high concentration of methane in the upper part of its atmosphere. At Neptune, shrouded in hydrocarbon haze, two main layers of clouds are distinguished: one consists of crystals of frozen methane, and the second, located below, contains ammonia and hydrogen sulfide.

Answer from Phibi[guru]
on Venus, most of it is carbon dioxide

Atmosphere on Wikipedia.
Check out the wikipedia article on Atmosphere

Dissipation of planetary atmospheres on Wikipedia
Check out the wikipedia article on Dissipation of planetary atmospheres

During a strong solar storm, the Earth loses about 100 tons of atmosphere.

Space weather facts

1. Solar flares can sometimes heat the solar surface to temperatures of 80 million F, which is hotter than the core.​​sun!
2. The fastest coronal mass ejection was recorded on August 4, 1972, and it traveled from the Sun to the Earth in 14.6 hours - a speed of about 10 million kilometers per hour or 2778 km / s.
3. On April 8, 1947, the largest sunspot in recent history was recorded, with a maximum size exceeding 330 times the area of ​​the Earth.
4. The most powerful solar flare in the last 500 years occurred on September 2, 1859, and was discovered by two astronomers who were lucky enough to look at the sun at the right time!
5. Between May 10 and 12, 1999, the pressure of the solar wind practically disappeared, causing the Earth's magnetosphere to expand in volume by more than 100 times!
6. Typical coronal mass ejections can measure millions of kilometers, but the mass corresponds to a small mountain!
7. Some sunspots are so cool that water vapor can form at 1550C.
8. The most powerful auroras can generate over 1 trillion watts, which is comparable to a moderate earthquake.
9. March 13, 1989 in Quebec (Canada) as a result of a major geomagnetic storm, there was a major accident in the power grid, causing a power outage for 6 hours. Damage to the Canadian economy amounted to $ 6 billion
10. During intense solar flares, astronauts can see bright flashing streaks of light from high-energy particles impacting their eyeballs.
11. The biggest challenge for astronauts traveling to Mars will be dealing with the effects of solar storms and radiation.
12. Space weather forecasting costs only $5 million a year, but saves over $500 billion in annual revenue from the satellite and electrical industries.
13. During the last cycle of solar activity, $2 billion worth of satellite technology was damaged or destroyed.
14. A repeat of a Carrington event like the one in 1859 could cost $30 billion a day for the US electrical grid and up to $70 billion for the satellite industry.
15. On August 4, 1972, the solar flare was so strong that, according to some estimates, an astronaut during the flight would have received a lethal dose of radiation.
16. During the Maunder Minimum (1645-1715), accompanied by the onset of the Little Ice Age, the 11-year sunspot cycle has not been detected.
17. In one second, the sun converts 4 million tons of matter into pure energy.
18. The core of the Sun is almost as dense as lead and has a temperature of 15 million degrees C.
19. During a strong solar storm, the Earth loses about 100 tons of atmosphere.
20. Rare earth magnetic toys can have a magnetic field 5 times stronger than that of sunspots.

One of the striking features of the solar system is the diversity of planetary atmospheres. Earth and Venus are similar in size and mass, but the surface of Venus is hot up to 460°C under an ocean of carbon dioxide that presses against the surface like a kilometer-long layer of water. Callisto and Titan are large moons of Jupiter and Saturn, respectively; they are almost the same size, but Titan has a vast nitrogen atmosphere, much larger than Earth's, and Callisto is virtually devoid of an atmosphere.

Where do such extremes come from? If we knew this, we could explain why the Earth is full of life, while other planets near it look lifeless. By understanding how atmospheres evolve, we could determine which planets outside the solar system might be habitable.

The planet acquires a gas cover in different ways. It can spew steam from its interior, it can capture volatiles from comets and asteroids when it collides with them, or its gravity can pull gases from interplanetary space. In addition, planetary scientists are coming to the conclusion that the loss of gas plays just as important a role as its acquisition. Even the earth's atmosphere, which looks unshakable, is gradually leaking into outer space. The leakage rate is currently very low: about 3 kg of hydrogen and 50 g of helium (two of the lightest gases) per second; but even such a trickle may become significant over a geological period, and the rate of loss may once have been much higher. As Benjamin Franklin wrote, "A small leak can sink a big ship." The current atmospheres of the terrestrial planets and satellites of the giant planets resemble the ruins of medieval castles - these are the remnants of former luxury that has become a victim of robbery and dilapidation. The atmospheres of even smaller bodies are like ruined forts - defenseless and easily vulnerable.

Realizing the importance of atmospheric leakage, we are changing our understanding of the future of the solar system. For decades, scientists have tried to understand why Mars has such a thin atmosphere, but now we're surprised it has any atmosphere at all. Is the difference between Titan and Callisto due to the fact that Callisto lost her atmosphere before air appeared on Titan? Was Titan's atmosphere once thicker than it is today? How did Venus retain nitrogen and carbon dioxide but completely lose water? Did the hydrogen leak contribute to the origin of life on Earth? Will our planet ever become a second Venus?

When it gets hot

If the rocket has gained the second cosmic speed, then it is moving so fast that it is able to overcome the gravity of the planet. The same can be said for atoms and molecules, although they usually reach their escape velocity without a specific target. During thermal evaporation, the gases become so hot that they cannot be contained. In non-thermal processes, atoms and molecules are ejected as a result of chemical reactions or the interaction of charged particles. Finally, when colliding with asteroids and comets, whole pieces of the atmosphere come off.

The most common of these three processes is thermal evaporation. All bodies in the solar system are heated by sunlight. They get rid of this heat in two ways: by emitting infrared radiation and by evaporating matter. In long-lived objects, such as the Earth, the first process dominates, and, for example, in comets, the second. If the balance between heating and cooling is disturbed, then even a large body the size of the Earth can heat up quite quickly, and at the same time its atmosphere, usually containing a small fraction of the mass of the planet, can evaporate very quickly. Our solar system is filled with airless bodies, apparently mainly due to thermal evaporation. A body becomes airless if the solar heating exceeds a certain threshold, which depends on the strength of the body's gravity.
Thermal evaporation occurs in two ways. The first is called Jeans evaporation in honor of the English astrophysicist James Jeans, who described this phenomenon at the beginning of the 20th century. At the same time, the air from the upper layer of the atmosphere evaporates literally atom by atom, molecule by molecule. In the lower layers, mutual collisions hold the particles, but above a level called the exobase (at the Earth it lies at an altitude of 500 km from the surface), the air is so rarefied that gas particles almost never collide. Above the exobase, nothing can stop an atom or molecule that has enough speed to fly into space.

Hydrogen, as the lightest gas, is the easiest to overcome the gravity of the planet. But first he has to get to the exobase, which is a long process on Earth. Hydrogen molecules do not normally rise above the lower atmosphere: water vapor (H2O) condenses and falls as rain, while methane (CH4) oxidizes and turns into carbon dioxide (CO2). Some of the water and methane molecules make it to the stratosphere and break down, releasing hydrogen, which slowly diffuses upward until it reaches the exobase. Some of the hydrogen is leaking, as evidenced by ultraviolet images showing a halo of hydrogen atoms around our planet.

The temperature at the height of the Earth's exobase fluctuates around 1000 K, which corresponds to an average velocity of hydrogen atoms of about 5 km/s. This is less than the second space velocity for the Earth at this altitude (10.8 km/s); but the velocities of the atoms around the mean are widely distributed, so some hydrogen atoms have a chance to overcome the gravity of the planet. The leakage of particles from the high-velocity "tail" in their velocity distribution explains from 10 to 40% of the loss of hydrogen by the Earth. Evaporation of Jeans is partly responsible for the absence of an atmosphere on the Moon: gases emerging from under the surface of the Moon easily evaporate into space.

The second way of thermal evaporation is more effective. While Jeans evaporates the gas molecule by molecule, the heated gas can escape in its entirety. The upper layers of the atmosphere can absorb ultraviolet radiation from the sun, heat up, and expand to push air up. Rising, the air accelerates, overcomes the speed of sound and reaches the escape velocity. This form of thermal evaporation is called hydrodynamic outflow, or planetary wind (by analogy with the solar wind - the flow of charged particles ejected by the Sun into space).

Basic provisions

Many of the gases that make up the atmosphere of the Earth and other planets are slowly escaping into space. Hot gases, especially light gases, evaporate, chemical reactions and particle collisions eject atoms and molecules, and comets and asteroids sometimes blow off large chunks of the atmosphere.
The leak explains many of the mysteries of the solar system. For example, Mars is red because its water vapor has split into hydrogen and oxygen; hydrogen flew into space, and oxygen oxidized (rusted) the soil. A similar process on Venus resulted in a dense atmosphere of carbon dioxide. Surprisingly, the mighty atmosphere of Venus is the result of a gas leak.

David Ketling and Kevin Tsanle
Journal "In the world of science"

The earth is losing its atmosphere! Are we facing oxygen starvation?

The researchers were amazed by the recent discovery that our planet is losing its atmosphere faster than Venus and Mars due to the fact that it has a much larger and more powerful magnetic field.

This may mean that the Earth's magnetic field is not such a good protective shield as previously thought. Scientists were sure that it was thanks to the action of the Earth's magnetic field that the atmosphere was well protected from the harmful effects of the Sun. But it turned out that the Earth's magnetosphere contributes to the thinning of the Earth's atmosphere due to the accelerated loss of oxygen.

According to Christopher Russell, a professor of geophysics and a specialist in space physics at the University of California, scientists are used to believing that humanity is extremely lucky with the earth's "registration": the Earth's wonderful magnetic field, they say, perfectly protects us from solar "attacks" - cosmic rays, flares on Sun and solar wind. Now it turns out that the earth's magnetic field is not only a protector, but also an enemy.

A group of specialists led by Russell came to this conclusion while working together at the Conference of Comparative Planetary Science.

ODDITIES OF THE EVAPORATING PLANET: A LOOK INTO THE ATMOSPHERE

For the first time, it was possible to observe the processes occurring in the atmosphere of a planet far beyond the solar system.

Apparently, these processes are caused by a bright flash on the parent star of the planet - however, first things first.

Exoplanet HD 189733b is a gas giant similar to Jupiter, although about 14% larger and somewhat heavier. The planet revolves around the star HD 189733, at a distance of about 4.8 million km from it (and 63 light years from us), that is, about 30 times closer than the Earth to the Sun. It completes a full revolution around its parent star in 2.2 Earth days, the temperature on its surface reaches over 1000 ° C. The star itself belongs to the solar type, having approximately 80% of the solar in size and weight.

From time to time, HD 189733b passes between the star and us, which made it possible, by changing the luminosity of the star, not only to detect the presence of the planet, but also to show the presence of an atmosphere in it, and water vapor in the atmosphere (read: “There is water”). It was also found that it is constantly losing hydrogen, in fact, being an "evaporating" planet. With this "evaporation" turned out to be a rather complicated story.

In the spring of 2010, one of the transits - the passage of the planet between its star and us - was observed by the Hubble space telescope, which did not detect signs of either the atmosphere or its evaporation. And in the fall of 2011, while observing the transit of the same HD 189733b, on the contrary, he provided very eloquent evidence of both, fixing a whole gas “tail” leaving the planet: the “evaporation” rate calculated on this basis was at least 1 thousand tons of matter per second. In addition, the flow developed millions of kilometers per hour.

To sort this out, the Swift X-ray telescope was connected to the case. It was their joint work that made it possible for the first time to record interactions between a distant star and its planet. Swift observed the same transit in September 2011, and about eight hours before the start of work Hubble recorded a powerful flare on the surface of the star HD 189733. In the X-ray range, the radiation of the star jumped 3.6 times.

The conclusions of scientists are logical: located very close to the star, the gas planet received a fair blow as a result of the flare - in the X-ray range it was tens of thousands of times more powerful than anything that the Earth receives even during the most powerful (X-class) flares on the Sun. And given the huge size of HD 189733b, it turns out that the planet experienced an X-ray exposure millions of times greater than is possible with an X-class flare on the Sun. It was this exposure that led to the fact that she began to rapidly lose substance.

The atmosphere of HD 189733b evaporating under the action of a nearby star: an artist's view This is what HD 189733b looked like on September 14, 2011 in the lens of the Swift probe (combined image in the visible and X-ray range) The same image, but only in x-rays

During a strong solar storm, the Earth loses about 100 tons of atmosphere.

Space weather facts

1. Solar flares can sometimes heat the solar surface to temperatures of 80 million F, which is hotter than the core of the sun!


2. The fastest coronal mass ejection was recorded on August 4, 1972, and it traveled from the Sun to the Earth in 14.6 hours - a speed of about 10 million kilometers per hour or 2778 km / s.


3. On April 8, 1947, the largest sunspot in recent history was recorded, with a maximum size exceeding 330 times the area of ​​the Earth.


4. The most powerful solar flare in the last 500 years occurred on September 2, 1859, and was discovered by two astronomers who were lucky enough to look at the sun at the right time!


5. Between May 10 and 12, 1999, the pressure of the solar wind practically disappeared, causing the Earth's magnetosphere to expand in volume by more than 100 times!


6. Typical coronal mass ejections can measure millions of kilometers, but the mass corresponds to a small mountain!


7. Some sunspots are so cool that water vapor can form at 1550C.


8. The most powerful auroras can generate over 1 trillion watts, which is comparable to a moderate earthquake.


9. March 13, 1989 in Quebec (Canada) as a result of a major geomagnetic storm, there was a major power outage that caused a power outage for 6 hours. Damage to the Canadian economy amounted to $ 6 billion


10. During intense solar flares, astronauts can see bright flashing streaks of light from high-energy particles impacting their eyeballs.


11. The biggest challenge for astronauts traveling to Mars will be dealing with the effects of solar storms and radiation.


12. Space weather forecasting costs only $5 million a year, but saves over $500 billion in annual revenue from the satellite and electrical industries.


13. During the last cycle of solar activity, $2 billion worth of satellite technology was damaged or destroyed.


14. A repeat of a Carrington event like that of 1859 could cost the US electrical grid $30 billion a day and up to $70 billion for the satellite industry.


15. On August 4, 1972, the solar flare was so strong that, according to some estimates, an astronaut during the flight would have received a lethal dose of radiation.


16. During the Maunder Minimum (1645-1715), accompanied by the onset of the Little Ice Age, the 11-year sunspot cycle has not been detected.


17. In one second, the sun converts 4 million tons of matter into pure energy.


18. The core of the Sun is almost as dense as lead and has a temperature of 15 million degrees C.


19. During a strong solar storm, the Earth loses about 100 tons of atmosphere.


20. Rare earth magnetic toys can have a magnetic field 5 times stronger than that of sunspots.

One of the striking features of the solar system is the diversity of planetary atmospheres. Earth and Venus are similar in size and mass, but the surface of Venus is hot up to 460°C under an ocean of carbon dioxide that presses against the surface like a kilometer-long layer of water.

Callisto and Titan are large moons of Jupiter and Saturn, respectively; they are almost the same size but Titan has an extensive nitrogen atmosphere , much larger than that of the Earth, and Callisto is practically devoid of an atmosphere.

Where do such extremes come from? If we knew this, we could explain why the Earth is full of life, while other planets near it look lifeless. By understanding how atmospheres evolve, we could determine which planets outside the solar system might be habitable.

The planet acquires a gas cover in different ways. It can spew steam from its interior, it can capture volatiles from comets and asteroids when it collides with them, or its gravity can pull gases from interplanetary space. In addition, planetary scientists are coming to the conclusion that the loss of gas plays just as important a role as its acquisition.

Even the earth's atmosphere, which looks unshakable, is gradually leaking into outer space.

The leakage rate is currently very low: about 3 kg of hydrogen and 50 g of helium (two of the lightest gases) per second; but even such a trickle may become significant over a geological period, and the rate of loss may once have been much higher. As Benjamin Franklin wrote, "A small leak can sink a big ship."
The current atmospheres of the terrestrial planets and satellites of the giant planets reminiscent of the ruins of medieval castles - these are the remnants of former luxury, which has become a victim of robbery and dilapidation .
The atmospheres of even smaller bodies are like ruined forts - defenseless and easily vulnerable.

Realizing the importance of atmospheric leakage, we are changing our understanding of the future of the solar system.
For decades, scientists have tried to understand why Mars has such a thin
atmosphere, but now we are surprised that he even retained at least
some atmosphere.
Is the difference between Titan and Callisto due to the fact that Callisto lost her atmosphere before air appeared on Titan? Was Titan's atmosphere once thicker than it is today? How did Venus retain nitrogen and carbon dioxide but completely lose water?
Did the hydrogen leak contribute to the origin of life on Earth? Will our planet ever become a second Venus?

When it gets hot

If a
the rocket has gained the second cosmic speed, then it is moving so fast that it is able to overcome the gravity of the planet. The same can be said for atoms and molecules, although they usually reach their escape velocity without a specific target.
During thermal evaporation, the gases become so hot that they cannot be contained.
In non-thermal processes, atoms and molecules are ejected as a result of chemical reactions or the interaction of charged particles. Finally, when colliding with asteroids and comets, whole pieces of the atmosphere come off.

The most common of these three processes is thermal evaporation. All bodies in the solar system are heated by sunlight. They get rid of this heat in two ways: by emitting infrared radiation and by evaporating matter. In long-lived objects, such as the Earth, the first process dominates, and, for example, in comets, the second. If the balance between heating and cooling is disturbed, then even a large body the size of the Earth can heat up quite quickly, and at the same time its atmosphere, usually containing a small fraction of the mass of the planet, can evaporate very quickly.
Our solar system is filled with airless bodies, apparently mainly due to thermal evaporation. A body becomes airless if the solar heating exceeds a certain threshold, which depends on the strength of the body's gravity.
Thermal evaporation occurs in two ways.
The first is called Jeans evaporation in honor of the English astrophysicist James Jeans, who described this phenomenon at the beginning of the 20th century.
At the same time, the air from the upper layer of the atmosphere evaporates literally atom by atom, molecule by molecule. In the lower layers, mutual collisions hold the particles, but above a level called the exobase (at the Earth it lies at an altitude of 500 km from the surface), the air is so rarefied that gas particles almost never collide. Above the exobase, nothing can stop an atom or molecule that has enough speed to fly out into space.

Hydrogen, as the lightest gas, is the easiest to overcome the gravity of the planet. But first he has to get to the exobase, which is a long process on Earth.
Hydrogen molecules do not normally rise above the lower atmosphere: water vapor (H2O) condenses and falls as rain, while methane (CH4) oxidizes and turns into carbon dioxide (CO2). Some of the water and methane molecules make it to the stratosphere and break down, releasing hydrogen, which slowly diffuses upward until it reaches the exobase. Some of the hydrogen is leaking, as evidenced by ultraviolet images showing a halo of hydrogen atoms around our planet.

The temperature at the height of the Earth's exobase fluctuates around 1000 K, which corresponds to an average velocity of hydrogen atoms of about 5 km/s.
This is less than the second space velocity for the Earth at this altitude (10.8 km/s); but the velocities of the atoms around the mean are widely distributed, so some hydrogen atoms have a chance to overcome the gravity of the planet. The leakage of particles from the high-velocity "tail" in their velocity distribution explains from 10 to 40% of the loss of hydrogen by the Earth. Evaporation of Jeans is partly responsible for the absence of an atmosphere on the Moon: gases emerging from under the surface of the Moon easily evaporate into space.

The second way of thermal evaporation is more effective. While Jeans evaporates the gas molecule by molecule, the heated gas can escape in its entirety. The upper layers of the atmosphere can absorb ultraviolet radiation from the sun, heat up, and expand to push air up.
Rising, the air accelerates, overcomes the speed of sound and reaches the escape velocity. This form of thermal evaporation is called
hydrodynamic outflow, or planetary wind (by analogy with the solar wind - the flow of charged particles ejected by the Sun into space).

Basic provisions

Many
the gases that make up the atmosphere of the Earth and other planets slowly leak into space. Hot gases, especially light gases, evaporate, chemical
reactions and collisions of particles lead to the ejection of atoms and molecules, and
comets and asteroids sometimes tear off large chunks of the atmosphere.
The leak explains many of the mysteries of the solar system. For example, Mars is red because its water vapor has split into hydrogen and oxygen; hydrogen flew into space, and oxygen oxidized (rusted) the soil.
A similar process on Venus led to the appearance of a dense atmosphere from
carbon dioxide. Surprisingly, the mighty atmosphere of Venus is the result of a gas leak.

David Ketling and Kevin Tsanle
Journal "In the world of science"

The earth is losing its atmosphere! Are we facing oxygen starvation?

The researchers were amazed by the recent discovery that our planet is losing its atmosphere faster than Venus and Mars due to the fact that it has a much larger and more powerful magnetic field.

This may mean that the Earth's magnetic field is not such a good protective shield as previously thought. Scientists were sure that it was thanks to the action of the Earth's magnetic field that the atmosphere was well protected from the harmful effects of the Sun. But it turned out that the Earth's magnetosphere contributes to the thinning of the Earth's atmosphere due to the accelerated loss of oxygen.

According to Christopher Russell, professor of geophysics and specialist in space physics at the University of California, scientists are used to believing that humanity is extremely lucky with the earth's "registration": the Earth's wonderful magnetic field, they say, perfectly protects us from solar "attacks" - cosmic rays, flares on Sun and solar wind. Now it turns out that the earth's magnetic field is not only a protector, but also an enemy.

A group of specialists led by Russell came to this conclusion while working together at the Conference of Comparative Planetary Science.