All Questions

0
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0answers
2 views

Why does moon's highest altitude change during the year

I came across a question in which moon's highest altitude had to be calculated as seen from a certain latitude, also the month and the hour and the constellation in which moon would be in had to be ...
2
votes
0answers
6 views

Radiative Flux, Irradiance and Luminosity confusion

First of all I know there is a similar question here, but I feel is wasn't answered at all. My question is that I have seen many texts which says that Radiative Flux is equal to the Irradiance of a ...
1
vote
1answer
31 views

If you could bottle a photon would it have mass? [on hold]

Ok. A photon has no rest mass for the good reason that it has no rest energy. But what about a standing wave? There is fair belief that particles are standing waves, so perhaps nothing rests. So. ...
2
votes
1answer
144 views

What produces gravitational waves with “periods between about 100 - 8000 seconds”?

The Ulysses mission has a compelling story. I was sent to Jupiter to perform a gravitational assist shooting it out of the plane of the ecliptic in order to fly over the Sun's north and south poles to ...
2
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0answers
10 views

What fraction of the time is EM-L2 in darkness on average?

This answer to the question How wide is the Moon's umbra and penumbra at EM-L2? calculates the widths of the umbra and penumbra at a distance from the Moon equal to the distance from EM-L2 from ...
4
votes
3answers
98 views

cosmic-microwave-background - 2.7 degrees but does the Big Bang care?

The Big Bang is a proposed answer to the beginning of the universe, and the Cosmic Microwave Background or CMB is a central part of the evidence for it. Now suppose the measurement returned a ...
2
votes
1answer
82 views

Why hasn't the Earth fallen into the sun yet?

So the Earth's been orbiting the sun in a relatively stable orbit for billions of years now. during that time, it's been plowing through dust, and hit by comets and asteroids, presumably mostly from ...
1
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0answers
16 views

How can I get the fluxes of fetch_imaging_sample? - astroML

I'm working with astroML in Python and I need to get the fluxes from the magnitudes in r band of fetch_imaging_sample(). ...
2
votes
1answer
94 views

Why was helium hydride (HeH+) the universe's first molecule?

The abstract of the new Nature paper Astrophysical detection of the helium hydride ion HeH+ tell us that infrared spectroscopy from SOFIA detected ...rotational ground-state transition of HeH+ at ...
0
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0answers
36 views

How impermeable are the surfaces of the moon?

In the event that we want to dig into the surface of either face of the moon do we know yet if the surfaces of the moon are particularly difficult or particularly easy to dig in?
2
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1answer
45 views

Do we know the availability of any material suitable for solar cells on the moon?

Disclaimer: I have no formal training in any scientific field. Have we located any material suitable for solar panels already on the moon? Or does it appear that they would have be imported?
1
vote
1answer
25 views

Do we know the fluctuations and constant temperature depth of the moon?

Disclaimer: I have no formal scientific training. From what I understand, surface temperature effects on Earth extend only so far into the ground so that at a certain depth the temperature remains ...
2
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2answers
91 views

Why is the Earth called terrestrial? Can we call the Earth an ocean planet?

Why is Earth called a terrestrial planet even though it is 70% covered by water?
3
votes
2answers
109 views

Can anyone one show how speeds greater than c cause a paradox on a space time diagram?

So according to Relativity, time moves at different rates for different observers, and distant observers will actually disagree on the order of events. Now from what I gather this gets sorted out for ...
1
vote
2answers
59 views

How to determine the eccentricity, knowing the orbital speed and distance

How to determine the orbital eccentricity of a planet, knowing the instantaneous orbital speed of it and the distance from the Sun to the planet at that moment?
2
votes
3answers
91 views

Is there a far away probe that has recorded the light spectrum from Earth as if it were an exoplanet?

We analyze the light spectrum of stars and distant planets to know characteristics like: chemical composition, temperature, mass, etc. Starting from the same principle, a probe at the border of the ...
2
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2answers
172 views

Is blue light not traveling faster then red light in space?

I just can't understand why light and other massless particles are not traveling at different speeds? Gravity effects anything with a mass but light has no mass but a black hole, and weak lensing ...
1
vote
1answer
38 views

How wide is the Moon's umbra and penumbra at EM-L2?

Measuring the total width of the Moon's umbra and penumbra at EM-L2, 64,700 km, how wide would the shadow be?
0
votes
0answers
56 views

The reason why the Sun doesn't explode? [duplicate]

I know that the Sun is made up of hydrogen and helium. Also, hydrogen explodes when it touches a flame. But why does the Sun not explode?
3
votes
4answers
698 views

Black hole density

How does more compression relate to a stronger gravitational pull. Like, when we say that a black hole is a tiny space that has 20-30 suns compressed in it, how does this increase its density and ...
1
vote
1answer
27 views

Existence of a mass-volume astronomical chart?

I've been wanting to make a mass-volume (or mass-radius) chart for astronomical objects ranging from asteroids to supermassive black holes on a log-log scale. A sort of 'Hertzsprung-Russel' type ...
-6
votes
0answers
55 views

Can Point Set Topology prove that the Alpha Centauri Double Star System is a mirage? [on hold]

The following diagram is a consequence of Apollonian groups. (1) If the diagram is to be taken seriously, a magneto-optic correction of the 137th order for charged particle telescopes will reveal why ...
1
vote
1answer
44 views

How to improve efficiency in periodicity detection?

Our data set has $10^4$ data points, but has a long baseline and many gaps. If we bin the data, there would be $10^8$ data points ($[t,\rm {value}]$), but only about 1% are non-zero values. How to ...
1
vote
1answer
90 views

What is that light of the middle of the milky way galaxy?

I'm Being confused what is that light in the middle of milky way galaxy? Image is from Charting the Milky Way From the Inside Out The text with the image explains a lot about the spiral arms and the ...
-1
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0answers
24 views

What is the Structure of Earth's atmosphere?

What are the Structure of the atmosphere of the earth and what is the difference compare to other planets ?
-1
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0answers
64 views

Are Torsors useful mathematics for modeling Spiral Galaxies? [on hold]

The local interstellar cloud seems to spiral into sunspots as time approaches positive and negative infinity - behavior I've always imagined representative of spiral galaxies. I am curious if any ...
1
vote
1answer
46 views

Difference of Gas Giant Planet and Ice Giant?

What is the Difference of or the Structure of a GAS PLANET AND AN ICE GIANT Why they called ICE GIANTS like Neptune and Uranus. Do they have a similarity ?
1
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0answers
8 views

Clarity on dust extinction terms and implementation: R_V, A_V, and E(B-V)

I have created a model galaxy spectrum using STARBURST99 and want to compare it to an observed spectrum of a particular galaxy. I understand that I need to redden ...
2
votes
0answers
15 views

How to correct observed flux densities for redshift

Say I have a spectrum of a galaxy at a redshift $z$, in flux density units of erg/s/cm^2/Angstrom. I'd like to recover the spectrum (in the same flux density units) at z=0, i.e. at its rest ...
2
votes
0answers
81 views

How does the black hole at the center of M87 look like in the visible spectrum?

I learned here that the picture of the black hole we saw all over the news was a false color image, based on the radio spectrum emissions. How would the black hole at the center of M87 look like when ...
0
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0answers
32 views

The Size of the Observable Universe [duplicate]

In the history it has been demonstrated that the galaxies have gone away between if there is another thing that has allowed us to calculate the value of the acceleration of the expansion that ...
2
votes
1answer
43 views

How do radio telescopes gather information about visible light?

Is the first image of a black hole that was captured by the Event Horizon Telescope what would be seen with a large enough optical telescope (or with the naked eye from a proper distance of the black ...
5
votes
1answer
73 views

What is the force that changes a satellite’s inclination when orbiting a planet with an equatorial bulge

I tried looking this up without success and I imagine there's a formula for it, with some ridiculous numbers like it drops off to the 5th power of the distance or maybe even more. Imagine a planet ...
0
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1answer
71 views

Can we get the gas compositions from a gas planets? [on hold]

Is it possible to get some gases like hydrogen from gas planets (Saturn, Jupiter, Uranus or Neptune)?
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0answers
26 views

On finding yesterday's star setting time if today's rising and culmination time is given

A star will rise today at 14h 56m and will culminate at 21h 49m. At what time yesterday did the star set? The refraction and horizon lowering can be disregarded.
-1
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0answers
44 views

About black hole [closed]

Is it possible that the center of Universe is a big massive black hole and all the galaxy move around it on its axis due to attraction of massive black hole? And after long time all the gallay are end ...
1
vote
1answer
111 views

What is the farthest we can see into the universe?

Is there a limit in which the mass in space obscure the ability to detect anything farther even as technology progresses? Related: Can the range of the observable universe be extended through an ...
1
vote
2answers
46 views

Knowing the RA/DEC of a star how do i locate a star from ground?

Standing in Melbourne at 4 am in the morning on 14th April 2019, Sirus RA = 06h 45m 08.9s, Dec = -16° 42' 58"..How do I Locate this. Standing facing east I turn myself towards south approx 90 Deg and ...
2
votes
2answers
80 views

Can the range of the observable universe be extended through an intermediary?

I understand that the so called observable universe has a limit we cannot see through. My question is whether we might get information through an intermediate hypothetical actor located halfway to ...
4
votes
1answer
85 views

Are we looking for brown dwarfs where the dark matter has to be?

We have been repeatedly assured that their ain't enough brown dwarfs to account for all the dark matter in our galaxy. My question is have we been looking in the right places? Or in more detail. ...
0
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0answers
21 views

Black hole rotation and it's significance

Is there is any significance of the direction of black hole rotation with the nature of the instantaneous distortion of space-time curve, the jets coming up in the axis of black holes, and nature of ...
5
votes
1answer
298 views

Where is the intervening light in the M87 black hole?

The M87 black hole is at the centre, more or less, of an elliptical galaxy of 1 trillion or more stars. So certainly there are stars and other light emitting objects (emission nebula e.g.) in the ...
0
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1answer
29 views

Does interstellar cloud obstruct or reduce the visibility?

We just pictured a medium distant black hole by combining data from various observatories around the world. That's when I wondered if interstellar cloud blocks the visibility at multiple position in ...
1
vote
1answer
31 views

How does the Large Binocular Telescope resolve so well in both orthogonal directions simultaneously?

The Forbes article Ask Ethan: How Does Very-Long-Baseline Interferometry Allow Us To Image A Black Hole? includes an example of optical interferometry from the Large Binocular Telescope, shown below. ...
2
votes
1answer
47 views

What does the Sun look like from the heliopause?

I calculated the angular diameter of the Sun at the heliopause to be 0.004°. If that is correct, would the Sun appear as a disk, or like the pinpoint of light from a star? How bright would the ...
6
votes
4answers
388 views

Why does the Event Horizon Telescope (EHT) not include telescopes from Africa, Asia or Australia?

The Event Horizon Telescope seems to include these radio telescopes currently: Image by European Southern Observatory (ESO)/O. Furtak; CC-BY 4.0-licensed, see the source on Wikipedia Commons and the ...
5
votes
1answer
76 views

Superscript-subscript uncertainty notation

While reading publications in astrophysics I've encountered this kind of notation (fictitious example): $$M = 6.1^{+0.6}_{-0.1} \times 10^{30} \textrm{ kg}.$$ Several examples are here, p. 2. I ...
0
votes
0answers
49 views

What would happen if two objects in two different black holes were connected by an infinitely strong rope? [closed]

I´ve read the answers to this, this, this, and especially this question, and still have questions about how black holes work. Two objects connected by a rope are released into two black holes. As ...
0
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1answer
84 views

Could the Sun have liquid iron in orbit?

How close of an orbit to the Sun could an iron meteor get before it melts into a ball?
0
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1answer
80 views

If a black hole does not emit light, how can one take a picture of the black hole itself?

There's some discussion that the image composed by the Event Horizons Telescope is really just an accretion disk. To "take an image" of something, you need the light reflecting off of the surface of ...

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