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Questions tagged [observational-astronomy]

The methods and techniques for gathering astronomical data, as well as the limitations thereof.

While is mostly concerned with studying the contents of the universe via whatever means are available, directly pertains to the data-gathering methods themselves.

Use this tag for questions pertaining to how we can observe astronomical objects, as well as for what physical limitations are encountered. This can include, for example, questions about

  • How large a telescope is needed to observe a particular object;
  • How the atmosphere interferes with astronomical observations;
  • Which phenomena can be detected in radio waves, or gamma rays; or
  • The particulars of photometry, spectroscopy, or interferometry as employed in astronomy

are suitable for this tag.

On the other hand, questions only concerned with the data itself, rather than the acquisition of that data, should probably be tagged and not . Similarly, if one is only concerned about underlying physical theories, would be more appropriate than .

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What is the most compelling evidence of General Relativity in the presence of matter and energy?

The most oft-cited triumphs of GR are things such as the shifting perihelion of Mercury, gravitational redshift experiments, and gravitational lensing. But, as far as I know, these are only verifications of Einstein's equation in a vacuum:…
Bridgeburners
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Why do stars flicker?

Why do stars flicker and planets don't? At least this is what I've read online and seen on the night sky. I've heard that it has to do something with the fact that stars emit light and planets reflect it. But I don't get it, isn't this light, just…
user25857
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How can one get the eccentricity of the orbit of the Sun around center of the Milky Way?

How can one get the eccentricity of the orbit of the Sun around center of the Milky Way? Can it be measured?
Alfavoufsila
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What made us think that Earth moves around the Sun?

Trying to observe the night sky for a few weeks, the motion of the Sun and the stars pretty much fits into the Geocentric Theory i.e. All of them move around the Earth. What then, which particular observation, made us think that it could be the…
Cheeku
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Observing Jupiter's non-Galilean moons

What strength of telescope is required to observe some of the non-Galilean moons of Jupiter? My current telescope at 50 magnification resolves the Galilean moons well, but I'm guessing it's far below what's needed to observe any of the smaller…
jball
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Milky Way Voyeurism

When and where on earth do we get the best view of the Milky Way? I believe it helps if it is night if it is winter to look in the direction of the galaxy center I think that this information from wikipedia: The Galactic plane is inclined by…
hpekristiansen
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What are the different ways to measure the spatial curvature of the universe?

Just what the question asks. Assuming the Friedmann-Rovertson-Walker (FRW) metric, what measurements can be performed to determine the spatial curvature of the universe.
user26866
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How does nuclear war look like from space?

As today's the 29th anniversary of possible Armageddon, had Mutual Assured Destruction taken place, with the USA and USSR exchanging most of their nuclear arsenal, what would someone In low earth orbit On the moon On Mars observe with the naked…
Gnubie
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Is it possible that I just saw Jupiter's moons?

Today at about 18:00 I was looking for Venus near the moon and I saw a short bright line. I thought that maybe I was seeing Venus' crescent but it was perpendicular to the crescent of the moon. I then noticed Venus very close to the moon and…
dotancohen
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How do I use this 'Horizon Observatory'?

Just around the corner, we have one of these: It's at the Halde Hoheward (article in the German wikipedia), and it's called a 'Horizon Observatory' by the people who built it. How does it work exactly, and how do I use it? A note: clearly, I need…
Stefano Palazzo
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How do we estimate $10^{23}$ stars in the observable universe?

Now, I read somewhere, that there are $10^{23}$ stars in the observable universe. How did scientists estimate this?
Harshfi6
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Why is the Hubble Space telescope able to see farthest in the universe?

What determines how far a telescope can see in the universe? How does recording data for a very long time (~10 years) help? If we could build a telescope which work at microwave region, will it be a better telescope (so that we could see even…
curious
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View of the Sun from Voyager 1

Today Voyager 1 is approximately 122 AU distance from the Sun. What does the sun look like from this distance? How much brighter does the sun appear to the naked eye compared to other stars in the same field of view? Are any of the other planets…
steampowered
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For observing planets what kind of telescope offers the best view?

I've heard that using a refractor is better than a reflector when it comes to planets to best reproduce their colors. But perhaps other factors can weight in too? For example, do you want a slow or fast f-stop to get the best view of a planet? …
WilliamKF
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What is the luminosity of the Milky Way galaxy?

The luminosity of the Milky Way galaxy according to this is $5\times10^{36}$ Watts, but this number suggests that there are about 10 billion stars with Solar luminosities in the Milky Way, which doesn't sound right considering that the Milky Way…
Abanob Ebrahim
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