Questions tagged [atmospheric-effects]

Questions about the influences of Earth's atmosphere on astronomical observations.

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When measuring the spectrum of an object at the zenith, is it better to orient the spectroscopic slit N-S of E-W?

If you were to measure the spectrum of an object while it's exactly at the zenith, how should you orient the slit of the spectrograph to minimise atmospheric dispersion? Is North-South or East-West ...
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What conditions are necessary for the sun to look [as described below]

First of all sorry for the weird title. I have no idea how to describe it in a succinct way because I've never heard of something similar happening and I've only witnessed it once. The only way for me ...
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1 vote
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How would the surface of Mars compare with the Atacama desert for millimeter wave (and shorter) radio astronomy?

In this answer to What kind of experiments would a scientist do on Mars? I suggest that the resemblance of the ALMA array's site in the Atacama Desert to the surface of Mars suggests millimeter ...
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4 votes
3 answers
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Fixed star-like light appears for a second or two - is there a way to find out what it was?

I saw what I can only describe as a fixed point of light, as bright as a shooting star, near Alpheratz for a second or two before disappearing. I am positive it wasn't a satellite nor a plane. There ...
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Why are fewer stars seen next to the horizon?

I was in the desert the other day, in an area that was free of light pollution. While it was easy to see the stars above us, I noticed that near the horizon, even when there is no distance light, we ...
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What are the oxygen or water vapor lines?

I was reading the document Recommendation ITU-R P.676-11 (09/2016); Attenuation by atmospheric gases (P Series, Radiowave propagation) in order to calculate the atmospheric losses, and there were some ...
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14 votes
4 answers
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What it the outer part of the sun, that we see with our eyes, called?

When we look at the sun with our eyes it seems much larger than it actually is. When we use a solar filter we are seeing what the sun actually is. So, what is the name of the thing the solar filter is ...
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How precise are Saemundsson/Bennett refraction formulas?

I was trying to reproduce the predictions of the Bennett formula* by physically-based calculations with a model based on a real-life refractivity profile. My calculations based on Table V from ref. 1 ...
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Why could I so easily see and photograph such a bright totally eclipsed Moon from a bright city road? (May 26, 2021 total lunar eclipse)

Due to scheduling and geometry I could only snap last night's lunar eclipse with an older model cell phone on a pedestrian overpass of a brightly lit city street, but surprisingly the Moon was quite ...
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10 votes
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Do radio telescopes see other stars better at night?

As you know, we don’t see stars with the naked eye during the day because of the visible glare of our Sun. As I understand our Sun emits radio frequency waves, too. Is there a radio ‘glare’ from the ...
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How do they know the TNT equivalent of the meteor explosion over Vermont?

I've seen several reports of this meteor explosion, below are two. Was there infrasound recordings of the pressure wave, or were weak, local seismic signals recorded, or it this just a ballpark ...
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3 votes
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Why do some stars twinkle more than others?

This is a child's question I failed to answer. When observing some stars with naked eye, some stars (e.g. Regulus) appeared to blink significantly more than others, but I did not have the patience to ...
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4 votes
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Effect of particulates on the visibility of stars?

I am looking for a (mathematical) relationship - either empirical or theoretical - which quantifies how the visibility of celestrial objects decreases with increasing amount of particulates in the air....
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3 votes
2 answers
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Understanding energy loss in a telescope aperture due to atmospheric dispersion

I'm trying to understand energy losses due to atmospheric dispersion, given the plot below from the Keck telescope. For a typical seeing I'm told that there's 80% encircled energy in 1". The ...
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6 votes
1 answer
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Do stars twinkle when seen from Mars' surface?

Mars' average atmospheric pressure is 0.006 atm (0.088 psi). Is that enough to make fixed stars on Mars' night sky twinkle? Do we know an air pressure or density limit for that?
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Source of red in earth's photographs

What is the red in this picture of earth? At first we thought it might be pollution, but Jupiter also has red. Picture source: https://education.seattlepi.com/primary-movements-motions-earth-4701....
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-1 votes
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If the Earth circled a red dwarf/giant or a brown dwarf, would its sky still look blue? [duplicate]

I have the impression that in brown dwarf and weak red dwarf systems, everything looks more reddish on a planet, including its atmosphere regardless of composition. Suppose there's a planet having an ...
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Why do in general stars twinkle and planets don't? [duplicate]

I got an email update on what can be observed this week. Jupiter looks like a bright yellow-white star, almost as bright as Mars. Saturn is about 10 moon widths to the left and slightly above, and is ...
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1 answer
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Can an average person see stars from the bottom of a well or through cardboard tubes? Definitive answer required!

A debate about seeing stars or planet during the day below this answer to the Aviation SE question At what altitude might a pilot be able to see at least the brightest stars during the day? seems ...
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3 votes
1 answer
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How far can we detect lightning in radioastronomy?

The wikipedia article on whistlers has this information: Voyager 1 and 2 spacecraft detected whistler-like activity in the vicinity of Jupiter known as "Jovian Whistlers", implying the ...
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Would a red dwarf star resemble our own Sun at sunset to an observer on a nearby planet?

Suppose you're observing a red dwarf star at Noon from the surface of an Earth-like planet orbiting in the red dwarf's habitable zone, so that the red dwarf's luminosity is equal to our own Sun. Aside ...
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A question about Sun disk deformation

Suppose the Sun rises and due to refraction the Sun's disc gets deformed. Let the center of the sun be $O$ and $OL$, $OR$, $OT$, $OB$ be the distances from the center of the disc to the edges in the ...
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3 votes
2 answers
221 views

Which kinds of astronomical observations most need to avoid the Moon being up?

This comment to Did nobody in the Astronomy community think 12,000 new satellites in LEO might be a problem? links to Phys.org's New ESO study evaluates impact of satellite constellations on ...
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6 votes
2 answers
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Why is blue light extincted more strongly than red?

We know that blue light suffers extinction more strongly than red (examples include ISM, atmosphere etc.), but why? Is it a property of the shorter wavelength itself? Can someone provide a conceptual ...
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5 votes
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When are wedge prisms used to correct chromatic effects of atmospheric refraction? (atmospheric dispersion)

Atmospheric refraction (shown below) happens because Earth's atmosphere has an index of refraction that differs from unity. @MikeG's comment mentions that this refraction would have a chromatic ...
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3 votes
1 answer
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What can be learned from low frequency radio astronomy available outside of Earth's ionosphere?

As discussions and answers to How large does refraction become in radioastronomy? point out, it is difficult to do radio astronomy much below 30 MHz (or 10 MHz depending on how aggressive you are in ...
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2 votes
2 answers
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What is the horizontal distance needed to observe an object just as badly as if it where in space at the zenith?

When I see an object in space (let's say the ISS) above my head, my line of sight traverses ~$100\; km$ of atmosphere. The vast majority of the extinction, absorption and turbulence happens closer to ...
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When and where are we exposed to most cosmic radiation?

I understand the mechanical dynamics of being faced away from the Sun at night, having a lower altitude, not being in the weak points at the poles in the atmosphere, being in a valley and others ...
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2 votes
1 answer
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How could the polarizer in early coronagraphs make the Sun's corona more visible against the daytime sky?

Wikipedia's Coronagraph; Invention says: High Altitude Observatory's Mark IV Coronagraph on top of Mauna Loa, uses polarization to distinguish sky brightness from the image of the corona: both ...
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3 votes
1 answer
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Why would atmospheric absorption increase rather than decrease the antenna temperature in Penzias and Wilson's famous CMB observation?

The classic paper A MEASUREMENT OF EXCESS ANTENNA TEMPERATURE AT 4080 Mc/s begins: Measurements of the effective zenith noise temperature of the 20-foot horn-reflector antenna (Crawford, Hogg, and ...
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4 votes
2 answers
264 views

Why is only a narrow chunk of sky darkened in this amazing Curiosity solar eclipse GIF from Mars?

I found three NASA JPL images in the sequence PIA23133, PIA23134, and PIA23135. They were taken by the Curiosity Rover on Mars and show solar eclipses by Mars' two moons. Details of these images are ...
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1 vote
1 answer
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Was is the angle needed to see a glory (a rainbow-like effect) from space off the Earth? [closed]

What positions would the Earth, Sun and viewer need to be to see a glory (a rainbow-like effect) from space? What position would they need to be in to reproduce this picture? Source: Gizmodo (NASA ...
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13 votes
2 answers
332 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 ...
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3 votes
2 answers
162 views

What is meant by "there is no refraction at the zenith"?

Wikipedia states: Atmospheric refraction of the light from a star is zero in the zenith and other sources seem to agree. I don't see why this should be so. Consider a situation in which air gets ...
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11 votes
3 answers
301 views

How would rainbows appear on other planets?

Are other planets capable of producing rainbows? How would those rainbows appear? Can rain, clouds or ice from elements other than water produce rainbows? Related: https://space.stackexchange.com/...
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4 votes
1 answer
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Under what situations can an aperture mask improve the resolution of a small/medium amateur telescope? Is this demonstrable mathematically?

@antlersoft's answer describes some of the challenges to seeing any details in the small disk of Mars in small amateur telescopes. In the case of reflecting telescopes, it mentions the use of either ...
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4 votes
2 answers
681 views

Why is it that night has a almost a bluish tint to it instead of red?

From my understanding/been told, the color red has the ability to travel the farthest in our atmosphere, being the reason why we have red sunsets and such. But with this in mind, why is it that at ...
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0 votes
1 answer
135 views

Why is the opening in the Anglo-Australian Telescope's dome so small?

Many older or "classic" telescope domes have a horizon-to-zenith opening in the dome, and this helps speed up the thermal equilibration between the inside and outside air, decreasing turbulence and ...
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1 vote
3 answers
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Adiabatic versus convection

I am reading about the interior temperature structure of Jupiter. It says in various texts that there are regions in Jupiter's atmosphere which are well-approximated by a dry adiabatic lapse rate. ...
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5 votes
1 answer
102 views

Impact of Atmospheric Water vapour on Optical Observations

I would like to ask; how does Water Vapour in the atmosphere interfere with astronomical observations? Is it in the same manner as Carbon dioxide? What brought this to mind is the following: A ...
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12 votes
1 answer
349 views

How would astronomical seeing on Mars differ from that on Earth?

Astronomical seeing is the limiting factor for the resolution of all but the smallest Earthbound telescopes. Source Stunning advances in adaptive optics (along with it's predecessor speckle ...
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7 votes
1 answer
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Is it possible to see Saturn from Titan's surface, day and night?

Titan is the only moon in our solar system with a thick atmosphere, similar to what our Earth's atmosphere was before life "appeared". It also orbits Saturn close enough to actually see it beautifully ...
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-2 votes
1 answer
160 views

Looking at ourselves with a powerful telescope?

Could a small curved mirror and/or lens in Earth's orbit be aimed at a different hemisphere from where you are be be viewed with a powerful telescope to see the ground through the mirror? Would a more ...
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3 votes
1 answer
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Would an extremely bright star produce same kind of shadow band effect as seen in solar eclipses just before totality?

This answer explains that the shimmering patterns seen on surfaces at the moment before totality of a solar eclipse are called shadow bands, and that the phenomenon is closely related to the twinkling ...
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5 votes
1 answer
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What is causing this strange shimmering pattern of light during a total solar eclipse?

Below this question was left a comment linking to the Smarter Every Day video Space Station Transiting 2017 ECLIPSE, My Brain Stopped Working - Smarter Every Day 175. At about ...
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7 votes
2 answers
373 views

How will "modern equipment" allow the Royal Observatory to now avoid some of the effects of light pollution at Greenwich?

The article First Light: a new era for the Royal Observatory says (in part): 25 June 2018 The first modern, research-grade telescopes have just been installed at the Royal Observatory Greenwich, ...
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52 votes
5 answers
17k 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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4 votes
1 answer
451 views

Formula for sun's atmospheric refraction below the horizon

I have searched in Google and found interesting articles for atmospheric refraction influence on sun's elevation above the horizon (from 0° till 90°). eg. Bennett G.G. etc. I would like to know if ...
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3 votes
1 answer
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Scattered Intensity of Light vs Angles of Incidence and Emission

So I just derived an expression for the scattered intensity of light from an atmosphere with ideal isotopic scattering: $I/F=\frac{cos(i)}{4(cos(e)+cos(i))}$, where $I$ is intensity, $F$ is flux, $i$ ...
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3 votes
1 answer
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What is tilt anisoplanatism for Laser-guide-star usage in adaptive optic systems?

How does tip-tilt mirrors correct such issue? What is the physical origin of the error?
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