Questions tagged [atmosphere]

Questions regarding a layer of gasses surrounding a celestial object.

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52
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5answers
13k views

Why is moon light not the same color as sunlight?

The light from the moon is light being reflected from the sun. The sun, in space, is white. But on Earth, when the light is filtered through an atmosphere, the light appears yellow. So then, why is ...
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2answers
3k views

Why has Venus's atmosphere not been stripped away by solar wind?

This answer on Space Exploration to a question about Mars says that one reason Mars has such a thin atmosphere is because it lacks a magnetic field to protect it from the effect of double solar winds. ...
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2answers
7k views

Why doesn't the moon twinkle?

Stars twinkle because their light has to squeeze through several different layers of the Earth's atmosphere. So why doesn't the moon twinkle as well?
31
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1answer
1k views

How could a hobbyist astronomer determine apparent magnitude of a star?

Apparent magnitude is a rather complex way to determine the brightness of a star. Quoting the introduction text from the linked to Wikipedia page: The apparent magnitude (m) of a celestial body is ...
29
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1answer
3k views

Can a tectonically inactive planet retain a long-term atmosphere?

Can a planet be tectonically inactive and still retain a magnetosphere and protected atmosphere? How does that work? How else could a planet retain a thick atmosphere like Earth's for extensive ...
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2answers
28k views

Why did Venus not lose its atmosphere without magnetic field?

It is often stated that the magnetosphere not only shields the planet from cosmic radiation, but also prevents atmospheric loss. Why then did Venus not lose most of its atmosphere if it doesn't have a ...
23
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2answers
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Terrestrial Exoplanet Skies – I've Built a Visual Sky Chart. Is it Accurate?

I'm an artist (and science enthusiast) and I've been trying to find a comprehensive resource that would help me clearly identify likely sky colors (as perceived by human vision) for exoplanets that ...
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3answers
6k views

Why can't moon light (reflected sun light) turn the sky blue?

Does turning the colour of the sky blue need more luminous light? Does it depend on luminosity or some other factors are also responsible for this phenomenon? Why can't the moon light turn the sky ...
20
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1answer
234 views

How are the compositional components of exoplanet atmospheres differentiated?

How are exoplanetary atmosphere compositional spectra distinguished from those of the parent star(s), from the composition of the planetary surface or any other factor? Is it actually possible to ...
19
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6answers
8k views

What does forward modeling mean?

In my research on exoplanets, I have heard many people talk "forward modeling of exoplanet atmospheres". I don't know what the "forward" means in "forward modeling" and how it compares with "reverse ...
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4answers
7k views

How does Titan maintain its atmosphere?

Titan, which is smaller than Mars, has an atmosphere but Mars is not able to maintain its atmosphere. Even Luna (the Moon) doesn't have an atmosphere. Why is Titan able to hold an atmosphere, despite ...
17
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2answers
18k views

Does the Moon have any oxygen in its atmosphere?

Since the moon has gravity, it's almost impossible that there aren't some gasses trapped on the surface by the moon's gravity. Has any free-floating oxygen been found on the Moon? If so, in what ...
17
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1answer
160 views

Loss of atmosphere on Mars

If the atmosphere on Mars was once much thicker, how was it likely lost? Was it due to interaction with the solar wind, the small size of the planet, both, or something else, and approximately how ...
15
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1answer
1k views

How much clearer are stars in earths orbit?

As a child I remember my parents taking camping in California, and upon stepping out of the car I was awestruck at how thick the Milky Way galaxy was and at the number of stars everywhere. I've always ...
15
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2answers
261 views

Does Ceres have an exosphere similar to the Moon?

Thinking about the question and answers for Does the Moon have any oxygen in its atmosphere? begs the question, despite being considerably smaller than the Moon and further away from the sun, does ...
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2answers
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How can clouds form in Jupiter's atmosphere of Hydrogen and Helium?

Here is a graphic of cloud layers of Jupiter (source: Wikipedia): There are three distinct cloud layers of ammonia, ammonium hydrosulfide, and water. The temperature and pressure conditions seem to ...
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2answers
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Is Earth unique in its fairly clear atmosphere?

So, we have surface pictures from two alien planets, Venus (captured by the Venera 13), and Mars (captured by the rover). Both of these pictures appear to be very dusty. For Venus we see strong ...
13
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1answer
1k views

How can neutron stars have gaseous atmospheres?

Neutron stars can have small atmospheres. However, they also have extremely strong gravitationally pulls. Shouldn't the all the gas molecules be drawn to the star's surface, and become solids under ...
13
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2answers
381 views

What is the current accepted theory as to why Titan has retained its atmosphere?

Titan (moon of Saturn) is unique in that it possesses a very thick atmosphere. However, Titan is certainly is not the largest of the moons - Ganymede being larger. What is the current accepted ...
12
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1answer
2k views

Why do gas giants have clearly delineated surfaces, whereas the Earth's atmosphere fades into space?

I've just seen this Forbes article. Why do gas giants appear to have clearly delineated surfaces, whereas the Earth's atmosphere fades into space? Is it just a matter of scale? Or is there some ...
12
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2answers
4k views

Why argon instead of another noble gas?

I noticed that the atmospheres of Earth and Mars have a little bit of argon in them (1% to 2%). I checked Venus, too, which has 0.007% argon, but that's still more than any other noble gas in the ...
12
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2answers
293 views

What was the first astronomical measurement which demonstrated that “the Earth is surrounded by vacuum”?

The question Who was the first to realize that the Earth is surrounded by vacuum? was closed because some users felt it was answered by answers to a different question in an different SE site: Who was ...
11
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1answer
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Why doesn't Titan have a carbon dioxide atmosphere?

Earth's primitive atmosphere had large amounts of carbon dioxide, as did the ancient Martian atmosphere. Venus's current atmosphere is no exception either. So why does Titan have next to none of this ...
11
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3answers
7k views

Why is twilight longer in summer than winter and shortest at the equinox

I recently decided to set my alarm clock to wake me up when it is "dark" out. In the end, I decided to set my clock to the earliest time that nautical sunrise is in my state (Illinois) and stick with ...
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3answers
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How do we get to know the total mass of an atmosphere?

Since atmospheres don't end abruptly but gradually get thinner the higher you go, I wonder how we can get the total mass of an atmosphere if we don't know where exactly it ends. E.g. the Earth's ...
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1answer
115 views

Do brown dwarfs have stripes?

Brown dwarfs (BD) are often depicted with stripes. brown dwarf Jupiter Pictures of BD resemble Jupiter but brown dwarfs ...
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1answer
244 views

Is the wind's intensity on Mars similar to Earth?

I've read that in Mars' poles, the winds can be as fast as 400 km/h, when the poles are exposed to sunlight because the frozen $CO_2$ sublimes. I know that the Martian atmosphere is much thinner than ...
9
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2answers
295 views

Can we find out whether early Venus was Earth-like or not?

It has been speculated that Venus billions of years ago could've had a much different atmosphere with liquid water on its surface and possibly life. Partly thanks to the cooler young Sun. But is it ...
9
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1answer
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Why are Saturn bands much fainter than Jupiter's?

The atmospheric composition of both planets are very similar. Then why are Jupiter's bands more visible (North and South equatorial belt, etc.): Whilst Saturn's are not: (except for the storm of ...
9
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1answer
352 views

Would Europa be an ocean planet if it were in the habitable zone?

If a Europa-like body were in the Sun's habitable zone, let's say in an orbit between Earth and Mars, would the body become and remain a water ocean planet? In the habitable zone, the Sun would warm ...
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1answer
562 views

Could the earth's atmosphere have been partially stripped by a passing rogue planet?

I am involved in the fight between palaeontologists and aerodynamicists on the theoretical flight capabilities of the largest pterosaurs (who reached their climax in the Cretaceous and then ...
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1answer
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At what depth on Mars would the atmosphere have equal pressure of that on Earth?

I know the atmospheric pressure on Mars is less than that of Earth, and so is its gravity. However, I know that the deeper you go (e.g. in a cave or a hole that is dug), the more atmospheric pressure ...
8
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1answer
206 views

Why does Titan have an atmosphere while similar moons such as the Galilean moons don't?

The Galilean moons of Jupiter are similar in size to Titan and are also protected by their parent planet's magnetic field. How come only Titan is able to maintain an atmosphere?
8
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1answer
113 views

What is the projected range of the JWST to be able to detect exoplanet atmospheres?

Yesterday the K2 mission detected transit events of objects passing in front of a number of M dwarfs which could turn out to be rocky planets. If some of these planets host atmospheres, could the JWST ...
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2answers
630 views

Why did the Chelyabinsk meteor explode?

In February, a meteor entered the Earth's atmosphere over Chelyabinsk, Russia and exploded, producing a shockwave blast that damaged hundreds of buildings around the explosion site in Russia. But why ...
7
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1answer
136 views

What causes the abundance of dust to 'float' in the thin lunar atmosphere?

Several missions to the Moon have revealed a lunar horizon glow, such as the ones seen below by the spacecraft Surveyor 7 in 1968: Image source: NASA According to the NASA article "Model Helps ...
7
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1answer
118 views

Oldest Reference to Astronomical Seeing

I'm writing a paper on astronomical seeing. Sir Isaac Newton identified both the phenomenon and origin of astronomical seeing in his Opticks. He writes: ...
7
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1answer
191 views

Is it accurate to compare comets to clouds and rain?

I'm trying to avoid an opinion-based question, so before I outline the comparison I'm proposing, I will qualify the specific facts that yield this comparison. By focusing answers on the relative ...
6
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2answers
784 views

Why do some celestial bodies have atmospheres, and not others?

Question is rather self-explanatory. An answer touching upon how/why atmospheres are formed in the first place would be ideal as well. An example of such astral bodies would be The Earth and it's moon....
6
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1answer
285 views

What is the underwater temperature of Europa?

If Europa has an oxygen atmosphere with a water mantle, is it possible that there could be life under the crust of Europa ice on the ocean where it is warmer? What could be the temperature under the ...
6
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2answers
114 views

What are the conditions for an ionosphere to form?

What are the conditions for an ionosphere to form on a given planet? Factors I could think of are Class and age of the star the planet orbits Distance to said star Density and composition of the ...
6
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1answer
448 views

What causes the aurora of other planets to have different colors?

All I could come up with is it depends on the atmospheric composition of the planet as they will interact with the charged solar particles which might be true but is there is there a definite reason ...
6
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1answer
239 views

Gravitational pull needed to keep a gas in atmosphere

How can you determine the gravitational force needed to keep a particular gas in the atmosphere of a planet (for example, carbon dioxide (CO2))? I came across the following formula $\left(\frac{8RT}{...
6
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1answer
128 views

How are sulfuric acid clouds able to completely cover Venus?

It is a well-known fact that an opaque layer of highly reflective clouds of sulfuric acid completely shrouds Venus preventing its surface from being seen from space in visible light. This is mentioned ...
6
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1answer
174 views

How deep in Mars would a person not need insulation and pressure? [duplicate]

How deep in Mars' surface would one have to go to both not need a pressurized suit and be warm enough to just wear clothes? in other words is there a dept Goldilocks where you would only need an ...
6
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1answer
140 views

If water vapor is always blown away into space, how is it able to create chemical compounds on Venus?

This is the follow-up of this chem.SE question. According to Wikipedia, water vapor on Venus is present in trace amount (20 ppm). There are multiple reasons why Venus has very low water content: The ...
6
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1answer
294 views

Mars vs Venus: the retention of atmospheres in relationship to Earth

Correct me if I'm wrong, but the factors than enable a planet to retain or lose an atmosphere seem to be: 1. Magnetic Field, 2. Solar Winds, 3.Weight of Gases, 4. Planetary Temperatures. 5. Distance ...
6
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1answer
315 views

How can you determine the initial volume of a planet's atmosphere?

Since the surface pressure of a planet is determined by the mass of the column of gasses above it one would surmise that to determine the pressure you must know the volume and mass of the atmosphere. ...
6
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1answer
111 views

Equation for solar radiation at a given latitude on a given exoplanet?

I'm trying to find equations that would help me determine the amount of solar radiation hitting a certain latitude on a certain planet given the following inputs: the degrees of latitude of the ...
6
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1answer
82 views

What is the nature of bright spots found on Uranus?

The following text is from space.com which was written during the time of discovery of the first dark spot on Uranus: During the past decade, many bright spots have been seen on Uranus in both red ...