# All Questions

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26 views

### Artificial gravity using Permanent Magnet method [closed]

Is it possible to create an artificial gravity for space station by using floating/rotating permanent magnet the inner floor/living quarters to counter rotate the outer rotating station when creating ...
26 views

### An idea to construct moon habitat [closed]

There is a boulder on peak of tyco crater central peak.we can send a robot with simple tools to create rooms inside the boulder.isn't this much cheaper and safe place for astronauts to stay inside ...
84 views

### Population density of stars within $13$ light-years of us

This item from Fox News refers to "over 600 stars that came within 13 light-years of the sun". Because of the past-tense "came", they could have meant stars that are not now within 13 light-years of ...
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### How much photon is still in flight?

Since space is mostly empty, one might first think that the majority of the photons, e.g. emissions from the stars since the beginning of the universe, are still in flight and not absorbed by anything....
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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 ...
130 views

### How long is the Sun closer to Earth then Mars is?

A recent question at Space.se has generated a few comments that are interesting. But the answer to one particular comment to might address a lot of misconceptions. I imagine the actual halfway ...
22 views

### Doppler Shift Vs Gravity Assist for Frequency Shifts from Rotating Galaxies

Frequency Shift of Light Leaving Rotating Galaxies: Differences in Doppler Shift due to Radial Velocity Vs Frequency Shift due to Gravity Assist from a Rotating Galaxy A description of estimating ...
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### Moment of inertia of precession

How do you calculate the moment of inertia of a planet for the effects of precession only?
151 views

### Why is the Earth's magnetic field stronger than its neighbors?

[Edited] I've learned that the Earth's core is hot due to decay of radioactive elements, causing the liquid part of the core to stay liquid. This was stated as an explanation to why the Earth has a ...
32 views

### line of lights as bright as stars moving across the night sky [duplicate]

was in adams county wi. morning of nov. 24th and saw 3 lights moving across the sky from sw to ne .moving quite fast then noticed more coming from sw in total I counted 28 may have been more not sure ...
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### What is this gap between hot and cold Jupiters?

When plotting mass to semi major axis on exoplanets.org, there seems to be a gap between Hot Jupiters and Cold Jupiters. A lot of Jupiter-mass planets at less than 0.1 AU have been discovered, and a ...
8k views

### Is Jupiter still an anomaly?

I remember a few years ago hearing that Jupiter was an anomaly in the landscape of exoplanets. Back then, most Jupiter-mass planets discovered were Hot Jupiters, orbiting very close to their host star....
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### How many exoplanets have been found around binary stars?

This XKCD whatif talks about circumbinary and [the other kind of] exoplanets. How many such exoplanets have actually been discovered? I tried to look it up at exoplanets.org, but didn't find a column ...
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### Why does the solar wind switch to flowing straight by the time it reaches Earth?

Between 02:01 and 02:29 the new NASA Goddard video 5 New Discoveries from NASA's Parker Solar Probe explains finding # 4, A ...
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### How can I use my current camera whose zoom lens can't be removed behind an f/6 refractor for as an astrophotography?

I am looking at an Astrotech AT60ED (60 mm f/6 with a field flattener) and a Digi-Kit telescope adapter to do astrophotography, mainly deep-sky and I'm wondering if I can use my current Panasonic DMC-...
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### What is the temperature of the black hole?

Are black holes hot or cold? I was thinking because I wanted to know if there any human sustainable temperature so we can travel in it.
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### Aligning of 7 unidentified objects in the sky, what are they? What did I see? [duplicate]

So this morning (4th December 2019, 0518hrs) I was out turning my horses out in the fields and noticed a strange arrangement of what I perceive to be stars, only I’ve never seen it before and wondered ...
4k views

### How far apart are stars in a binary system?

I'm wondering how far apart from one another the stars are in binary systems. What is the distribution of the separation between binary stars? Are most of the binary stars very far apart like Sirius (...
61 views

### How does one find the electric conductivy of a planet's atmosphere?

I am working on an undergraduate project in which we study shaped structures in the atmosphere of the gas giants. We are investigating whether the magnetic field is the source of the instability ...
57 views

### Would it be possible for life found on moon of rogue planet

I have heard that there are at least three Basic requirement for life exist in the universe, they are: Source of Energy Complex chemistry (including solvent/medium for chemical reaction) Protection ...
246 views

### A Sky Map of Gravity - what would it look like?

PREAMBLE Sky Maps exist which show the distribution and intensity of electromagnetic radiation received on Earth at various wavelengths. An obvious form is a map of the stars (Star Chart). Maps ...
28 views

### Different sizes of bow shocks

In this image of LL Ori bow shock, there is a smaller bow shock at the upper right. Is that second bow shock substantially smaller than the LL Ori bow shock, or is it just much further away? If ...
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### What percentage of a spiral galaxy is the center/bulge?

Is there a credible source that can tell me how big the bulge of a spiral galaxy is compared to the rest of the galaxy? Unfortunately, I could not find any.
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### Can we violate law of physics in any other planet? [closed]

Can't there be any way to violates any law of physics? If in our earth we can't violate any law of physics can't we violate in any other planet?
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### Latitude of given altitude of Sun

From Question #6 of USAAAO First Round 2018 (1 point) For the following problem find the range in which the answer lies: on the day of summer solstice, on which geographic latitude is the sun ...
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### Galactic Coordinate System and distance

If the Galactic Coordinate System is made up of two values, angles of longitude and latitude, how is distance measured? If you have those two values, you get a line from the sun in a certain direction....
4k views

### Why does the 70-solar-mass black hole in the LB-1 system challenge current astrophysics?

Recently scientists discovered a large stellar-mass black hole, which (previously) they believed that it shouldn't be possible in our galaxy! Source An international team of scientists say they ...
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### Is there a way to know the time according the moon appearance?

Is it possible know the time according to the moon location? To look at the sky at night and then determine what the time is.
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### Finding the Uncertainty in a Spectral Line

Currently, I am doing a lab in school on atomic spectroscopy. After taking readings of strong emission lines of various elements, I have fit the data using a Voigt Profile function from lmfit. The ...
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### Redshift and Velocity relation

Let us say that we have a stellar object so its total velocity is defined as $$v_{tot} = v_{pec} + V_{rec}$$ Where $$V_{rec} = H_0r$$ ...
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### Are there any *client-side* JavaScript astronomy libraries? (not node.js)

Are there any client-side JavaScript astronomy libraries? Almost every library I see appears to be server side for node.js. I realize some node.js libraries can be adapted for client-side use, so I'...
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### what is the resolution of the magnitude that is distinguishable to the naked eye?

Or is it possible to spot the changing brightness (magnitude) of a planet with a naked eye The context of the question is this: If I'm not mistaken Ptolemy was able to say (using observation alone) ...
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### What are other names for planetoids that aren't orbiting a solar system, but hurtling through space?

I'm trying to think of a good word for an asteroid/planetoid that has no stable orbit but has been ejected from a system and is passing close to a sun. Any help?
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### Can “rock stars” form from interstellar dust?

Imagine a large and massive dust cloud made of solid phase micrometeoroids, asteroids and larger planetoids, all material in it is in solid phase, and contains no hydrogen or other volatiles in gas ...
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### Line of lights in the sky over Bedford United Kingdom [duplicate]

Saw multiple 'stars', 29 November about 4.00 am GMT. One at a time moving at 15 second intervals across sky in direction of South east. I counted over 50. At one point 12 lined up in a row and carried ...
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### Just saw 35 approx lights in the sky, [duplicate]

Just saw 35 approx lights in the sky, all moving in the same direction. When I saw the first 2, I presumed they were satellites as I've seen satellites and the iss before but I've never seen this ...
139 views

### Why do the magnetic field lines of the earth go from south pole to north pole?

I saw these figures and could not get why the magnetic field lines are not pointing from the north pole towards the south pole but they do the opposite. Or also this picture which is about magnetic ...
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### How to calculate Equivalent Width of a spectrum with continuum at 0

I am trying to calculate the Equivalent Width of emission lines of a spectrum whose continuum is at 0, making the calculation of the EW impossible. I have the spectrum of a transient in a galaxy, so ...
65 views

### Why would a black hole have a disk, but not emit x-rays?

There's a recent paper in Nature about LB-1, a B-class star orbiting a massive black hole. I don't understand how these two parts of the paper can be reconciled. On page 2, the authors argue that the ...
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### Sun and moon's orbit in ecliptic coordinates using skyfield

I am new to using skyfield, is there any doc or help file that can show me on how to get the orbit of Sun and moon in ecliptic coordinate for a particular date and ...
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### “Holes” discovered in the Milky Way Galaxy

Recently I read that Astronomers have noticed a few "holes" in our Galaxy. They are about one million times the mass of our Sun. They are baffled as to what could have caused this and speculate that ...
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### About more than 15 stars moving in straight line through the sky [duplicate]

I had seen more than 15 stars are moved in a straight line through the sky just like a train. And the distance between each star was not same, some of them were near and some of them were far. The ...
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### At what rate is the observable universe expanding?

The observable universe is $4.4 \times 10^{26} m$ in every direction. I told this to my daughter and then added, "And guess what? It's a little bigger today than it was yesterday." "Wow!" But by ...
182 views

### Any book on How do they know it (in Astronomy)?

I am reading my college level undergraduate astronomy textbook. It has lot of ínfromation but every page rises a similar question in my mind: "How do they know it?". It starts from simple things like ...
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### Units of freqency in Doppler broadening

What units of freqency are used in this formula please?
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### How to calculate parallactic angle from a fixed alt-az position?

Say we have an observer at a specified latitude and longitude on Earth who would like to observer a specific fixed alt-az sky position (rather than RA and dec), for example to look at geosynchronous ...
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### Orbits of planets in ecliptic coordinates

Is it possible to get the ecliptic coordinates of orbits of planets for a specific date and time? Does the ephemeris data of planets help in constructing that? Any help on this would be helpful. I ...