Questions tagged [observational-astronomy]
Questions about the techniques and practice of observing the night sky.
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Adaptive Optics?
I get the general idea of adaptive optics. The light from an object distorted by differences in the earth's atmosphere, and a telescope with AO tries to compensate for this distortion by various ...
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Save current state in ds9?
After fooling around with a FITS file(s) (e.g. setting scale, changing color) is it possible to save the session such that there is a file associated with all those tweaks the next time I open it up?
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How was an infrared picture of the entire universe taken?
(click to enlarge)
How was this picture of the supposed entire universe taken in infrared? Also, why does it seem as though almost all of the matter is in a line formation over the center? It makes ...
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Data for red-shifting
I am looking for basic data regarding red-shifting that comes with reliable measure of distance of the emitting star.
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Why can't we determine the center of the universe [duplicate]
I find this baffling. If we can observe objects moving away from us and each other, than it stands to reason that we can track their paths (relative to each other and ourselves) backward to find a ...
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Perception of an objects history passing as an observer moves toward it
If a star is 20 light-years away and I look at it through a telescope, what I'm observing is what the star was doing 20 years ago yes? So, if I fix my sight on the star and move toward it (for example'...
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What is this graph showing?
This is from the NED
What do these three titles mean?
log fb (Jy)
MRK 1014
Log v (HZ)
Why is there LINE,LINE,...
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Is it difficult to see DSO in your eyepiece?
I want to know if bringing the image of a DSO in eyepiece generally represents a problem for beginners in astronomy.
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How did Kepler determine the orbital period of Mars?
As I understand it, Kepler used the orbital period of Mars, along with observational data of Mars' and the sun's position in the sky to derive the orbits of Earth and Mars. (As described, here: https:...
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how does redshift prove expansion is accelerating?
My astronomy teachers never would answer this for me... Redshift obviously indicates an object (such as another galaxy) is moving away, but how do we know its acceleration from this? It's my ...
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Can I look at the sky and find the day of the week?
Suppose I wake up from a coma on a desert island in the 19th century (i.e. we already use the Gregorian calendar but have no satellites yet). I have a clear view of the sky and a couple of days to ...
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Point Spread Function size: Full Width Half Maximum (FWHM) vs Sigma
I having been studying some astronomy papers related to galaxy observations and I realized that every time they want to express the size of the Point Spread Function (PSF) of a system which can be ...
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Sensitivity of calculated orbital elements to observational errors
These days, we have some very precise ways of making measurements, but I'm sure it wasn't so in Kepler's day. So I am wondering how astronomers of that time could make such accurate determinations of ...
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How can we know the nature of the companion in a neutron star binary?
The companion of a neutron star could be a main sequence star, white dwarf, neutron star or black hole.
We detected a pulsar-pulsar binary several decades ago. But if one of the pulsar does not ...
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How would Alpha Centauri A appear from the surface of Alpha Centauri Bb?
I'm trying to imagine what a hypothetical observer on the surface of Alpha Centauri Bb would see in the daytime sky. I know it would vary depending on the orbit of b around B, as well as the position ...
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Please Guide me to buy my first Telescope [duplicate]
I am a beginner and I've planned to buy a telescope(Newtonian reflector)for viewing planets and deep sky objects. As far as I know the most important factor to get a brighter view is that the ...
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Are satellites orbiting around earth visible to the naked eye?
I was just lying under the sky trying to possibly see some meteorites, unfortunately never seeing any I might add, but I saw three objects all moving at about the same speed( all at different times). ...
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Why do Jovian moons fade when transiting Jupiter's shadow?
When reading an article on using Jovian moons to calculate longitude, I came across this passage:
Periodically, Jupiter eclipses each of the four large moons as they pass into the planet's mammoth ...
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Present distances between planet. How can I find them?
It's "commonly known" how distant are our solar system planets from Sun. But we can't easily say that about planets, which distances can differ greatly, without some observations (or simulations, ...
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How are rogue planets discovered?
Planets are usually found by observing a star and waiting for the light level to drop when a planet passes in front of it, but what about rogue planets that don't have host stars?
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How do one identify something they see in the sky?
I've always wondered how someone looking at the sky into the enormous amount of stars and other things out there figures out that whether it is an already identified object or is he looking at ...
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How do astronomers find interesting events?
I always wondered how those tiny dots representing moving stars or whatever forming an interesting event (supernova explosions, stars being sucked into black holes etc.) get caught in the huge solid ...
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Why can you see the space station on some days but not on others?
In my area, from December 17th - 26th, you can see the space station every day, twice
But from December 27th - January 6th, you can only see it twice
My question is, why does it appear for almost ...
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If we were to see the Sun with our naked eyes from the Orion belt, would all planets be encompassed inside the star? Is this calculable?
When we see a star it looks much bigger in diameter to us than it really is, this picture (extracted from here) explains what I mean:
Notice that the point we see in the skynight, represented by the ...
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Solar Noon: meridian crossing time versus time of maximum elevation
According to the first paragraph of the Noon Wikipedia page, solar noon is the moment when the Sun crosses the meridian and is at its highest elevation in the sky. The wording there suggests that ...
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When is optical refraction important in Astronomy? (beyond Earth's atmosphere)
What are commonly important astrophysical systems/models, where optical refraction is important or necessary to account for?
I would kindly ask you not to consider refraction in Earth's atmosphere or ...
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How to calculate the altitude of the Moon?
With the known latitude coordinate of the observing position, how to find the altitude of the moon when it is high, i.e when it crosses the local meridian?
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What are some night sky objects I could see with my Celestron UpClose 20x50 Porro Binocular?
I bought this binocular because I've read countless times that one should start with a pair of binoculars before diving into telescopes. I've seen details of the moon and I can notice Venus round ...
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What's the smallest scale at which dark matter has been measured?
What is the smallest scale at which we have detected "dark matter" (more kinetic energy than would be predicted)?
If you don't mind indulging a follow-up: Would its detection on smaller scales be ...
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How to calculate Longitude from Right Ascension?
Considering that a star of certain declination is crossing the local meridian at the observer's zenith at an unknown location on the earth. Here, the declination of the star is equal to the observer's ...
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How to measure the altitude and azimuth of a star?
Given that the star is crossing the local meridian line in a certain location, I've tried calculating the altitude of a star by finding the difference between the declination of the star and the ...
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At what distance from Earth would our Sun be the same apparent magnitude as the next brightest star in the sky?
When I stand outside looking at the night sky, to my untrained eye, everything except the moon looks like a star. I know intellectually that some are planets circling our sun, and some are entire ...
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What is the object in this photo?
What object is in this photo?
View coordinates: $47.25103 \ \ 38.81697$
Time: $2013$-$11$-$23 ~21$:$00 +4 ~UTC$
Sony $A580, \ 50mm f/1.4 15"$
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How would I measure that I'm at a pole?
How would a person measure that he is at a planetary pole? My first inclination is to use a sextant to ensure that the Sun remains at a constant inclination. However, due to the orbit around the Sun ...
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Open data for satellites positions
Is there a site / service where I can get the data for the positions of satellites (I mean artificial satellite, ISS, etc.)?
I know that some sites provide a visualization of these positions, but I'm ...
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Colossus telescope, trying to outsmart aliens?
I was listening to Jeff Kuhn's talk
on SETI's Colossus telescope project.
Background:
He explains his theory that a civilization living somewhere the galaxy would want to hide, and thus would ...
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Planned telescope to detect alien waste-heat
I remember watching a talk by someone who designed a telescope to view a single star at a time.
The purpose of the telescope was to detect waste-heat which would presumably be emitted by any ...
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Is it possible to observe if there is traces of life on an exoplanet?
We can observe exoplanets, but is it possible with today's technology to observe if there is life as we know it on an exoplanet? What do you look for when doing this kind of observation?
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How much did we know about asteroids at the beginning of the 20th century?
When was the nature and size of asteroids discovered? I was under the impression that it was not until the 1980s or 1990s with deeper space probes and Hubble imagery that we learned the nature of ...
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How can I safely observe a Solar Flare?
Solar Flares obviously release extreme amounts of energy and extend thousands of miles out into space.
Because they are so big I would like to be able to observe some of these events through a ...
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What study profiles could land me the job of astronomer?
I realize there are very few to none universities that offer direct specialization of astronomy. If I aspired to be make astronomy my career choice, I'd likely have to pick something like physics and ...
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How can an amateur astronomer verify the position of near Earth objects?
Sometimes, hobby-astronomers use rather professional means to observe the big voids of space. Every now and then (think in months, not days) even I can locate an NEO (near Earth object).
Now, I'm ...
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How can the orbit of a Kuiper Belt Object be differentiated from the transit of a rogue planet?
Related to the question "Are any Pluto-sized objects remaining to be discovered in the Kuiper Belt?" and the fact that most of the Kuiper Belt objects have very elliptical orbits, the question begs, ...
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How often do comets survive passage by the Sun?
I had heard that comet ISON might not survive a close pass by our Sun, and I was curious about the odds of how other comets had fared. So, how often do other comets survive a close pass by our sun? ...
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What observational constraints are there in detecting the presence of volcanism on exoplanets?
This question is somewhat related to my earlier question How are the compositional components of exoplanet atmospheres differentiated?, but this about a specific surface-atmospheric phenomena - ...
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What are the current observational limits on the existence of Dyson spheres/swarms/rings?
A Dyson sphere/swarm/ring is a hypothetical structure an extra-terrestrial entity would construct to collect a large fraction of its host star's light, and would likely generate a fairly strong ...
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Has Hawking Radiation Ever Been Observed?
I know Hawking Radiation has firm theoretical footing, but has a signal ever actually been observed? What observational research is being done to attempt to see this effect? Is it simply too tall an ...
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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 ...
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Why can't we observe the Oort cloud with a telescope?
The Oort cloud is a hypothetical structure based on our observation of long-period comets. There are currently proposals to design probes to confirm the existence of the Oort cloud.
Now, sending a ...
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How do I build a stargazing aficionado's Sun funnel to observe our nearest star safely?
How do I observe the Sun safely, with tools I could build myself and without breaking the bank? If I wanted to build a Sun funnel on my own and use it on my enthusiast grade telescope, how would I do ...
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