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13
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How complicated is the heating of meteors?
When any gas, including our atmosphere, is compressed, it's temperature rises.
When a meteor is falling through the atmosphere, it is compressing the air below it.
Because this makes the air hotter than the meteor, heat moves from the air to the…
BenGoldberg
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13
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How is an exoplanet characterised as "Earth-Like"?
Which features or characteristics are taken into account to characterize an exoplanet as "Earth-Like"?
Topcatmki
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13
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Pulses from a pulsar
What is/was the motivation behind attributing the pulses received from a pulsar to the rotation of an object (neutron star) and emission from the magnetic poles (of the said neutron star), given that fact that pulsars have not been resolved yet in…
user30981
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13
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How much mass does the Sun lose as light, neutrinos, and solar wind?
In this answer I estimate the loss of gravitational mass of the Sun to be about 1.3E+17 kilograms per year using $E = m c^2$ and 1360 W/m^2 at 1 AU.
While writing that answer I realized that solar neutrinos also carry away a lot of mass equivalence…
uhoh
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Why are telescope mirrors made of glass?
Optical telescope mirrors are typically made from endlessly polished glass surfaces that have been aluminised to provide a very smooth surface of reflective aluminium.
But why the need for glass at all? Why can't mirrors be made of pure metal, or of…
Ingolifs
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13
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The recent results on Hubble constant measurements
In recent news there is this announcement
In the introduction they say:
Distance measurement discrepancy: a $4.4σ$ tension on the value of $H_0$
and I understand the discrepancy is with the value derived using the cosmic microwave radiation (CMB).…
anna v
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13
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Can a system of three stars exist?
Just like binary stars can a system of three stars mutually equidistant from each other?
What I mean is three stars at the vertices of a equilateral
If yes than what will be the orbit of a planet out there
If no what will be the problem for it's…
Heth Ghetiya
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13
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How does angular resolution of a telescope translate to its parallax precision?
We can often read in the scientific and also more casual reader literature and articles about the angular resolution of various telescopes and other optical equipment, be it ground based or onboard space probes. They would often list their angular…
TildalWave
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What am I looking at here at Google Sky?
I was looking through the Google Sky map, when an object caught my eye:
I am really curious as to what this is (just a big star? then why does it look so peculiar?)
It's hard to search for online because I don't know which words to use. If anyone…
user2315111
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13
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Observable universe equals its Schwarzschild radius (event horizon)?
The estimated age of the universe is 14 billion years.
The estimated Schwarzschild radius (event horizon) of the observable universe is 14 billion light-years.
What are the ramifications?
Dirk Helgemo
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Sky photography through compositing images in software?
I've read about and seen some rather sophisticated rigs for night sky photography that allow for ultra-long-exposure photos by counteracting the rotation of the sky by rotating the camera with it. The problem is mechanics for such rigs is rather…
SF.
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How fast do we travel through space?
Could someone give the rough estimates of speeds of our travel through space?
I can easily find the two nearby ones:
Earth's own rotation - depending on latitude, up to 40,075 km/24h = 463 m/s
Earth's orbital speed around the Sun - 940 000 000…
SF.
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13
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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 the first to postulate that space was a…
uhoh
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13
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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/questions/34357/rainbow-space-probe
Muze
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How do we know if an object is redshifted?
I have some questions about redshift. I think that the first two hang on the last two, but feel free to point out anything you think I should know.
How do we know if an object is actually redshifted, and that we aren't just seeing the regular…
Gimcrack
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