6
votes
1answer
56 views

Is there a variation of ISO 8601 for julian calendar dates?

If I want to write a date in the Gregorian calendar, I can write it in the ISO 8601 format; today would be 2016-02-20. The advantage is that there are many parsers available to let computers read in ...
-2
votes
2answers
85 views

What is the current state of gravity in the vacuum of space? [closed]

Is Gravity in the vaccum of space decelerating or exspanding? please explain why,when and how in detail, Along with a credible reference. If Science has not concluded either please give a reference as ...
4
votes
1answer
75 views

Where is the flaw in this hypothetical concept of escaping event horizon using another's blackhole flyby?

imagine two black holes approaching each other in a way that they will perform just very close flyby. You have a spaceship just below the event horizon of one black hole in line between centers of ...
0
votes
1answer
48 views

Astronomy Olympiad Gravitation Qn

Question: Approximately once in 5 years people on Earth can observe bright comets whose nuclei have radius about 1km. The orbits of such comets are close to parabolic. Assuming that these nuclei are ...
6
votes
5answers
416 views

Are black holes really singularities?

Can't black holes just be super dense objects? They could still be black (having the color of black never really required special physics, after all) and have a really strong gravitational field. If ...
3
votes
1answer
76 views

Earth's Versus Catastrophic Meteor

How evasive is the Earth to Catastrophic Meteors? Google says the Earth is approximately 92.96 million miles from the Sun. It also says the suns radius is 432,474 miles. Therefore, it is 93,392,474 ...
3
votes
1answer
31 views

What is the formulat to compute King tracking rate for a given set of topocentric coordinates?

Canbury Tech has a good background on King tracking rate, which approximates the average sidereal motion of a refracted star across the sky. Most amateur telescope mounts have some sort of notion of ...
1
vote
2answers
58 views

Table of absolute magnitudes of stars by spectral type and photometric band

I would like to find a table where I can, say, look for K5 dwarfs and read off that stars of that type have on average an absolute magnitude of X.XX in the infrared L band and Y.YY in the G band. I've ...
5
votes
2answers
288 views

Does natural satellite(s) of a planet affects its orbital velocity around a star?

Please excuse me for a lay question. As we know, to calculate the orbital velocity, we take the mass of the orbiting body, the mass of the body being orbited and the distance between the two bodies ...
6
votes
1answer
102 views

Does LIGO have a blind spot?

If I understand the principle of operation of operation of LIGO, it detects relative distortions of the two perpendicular arms. So if both arms are distorted the same way, nothing would be spotted. ...
1
vote
1answer
88 views

Special Relativity as Applied to an Interstellar Starship?

I'm once again confused by the twin paradox. Let's say I am on an interstellar starship flying at 0.6c from a star 30 light years away from Earth to a star 50 light years away from Earth and 40 light ...
3
votes
1answer
43 views

what is the percentage of stars with planetary systems?

I'm having hard times understanding the equation of Drake, i can´t find the number of the variable that refers to the stars with planetary systems (fp)
2
votes
2answers
90 views

How fast can and do gravitational waves travel?

I was thrilled by the recent announcement of the detection of gravitational waves. The media has done a great job explaining them and the theory behind them and I get the concept fairly well. But if ...
2
votes
0answers
18 views

Telescope optical tolerance from central axis

I sometimes encounter telescopes/binoculars with a decent objective diameter but are very difficult to use because they only work when the eye is looking down the central axis (i.e. in the centre of ...
0
votes
1answer
47 views

Create Position-Velocity diagram from a velocity field

Can someone explain to me how I can generate a Position-Velocity (PV) diagram from a galaxy's radial velocity field? I understand that usually PV diagrams are generated across the major axis of the ...
1
vote
1answer
141 views

Do black hole singularities actually merge?

new questioner here so please be gentle. Do the singularities of merging black holes actually merge together? I mean there are 2 infinitely small objects (singularities) that are trying to find each ...
11
votes
3answers
128 views

Frequency of gravitational wave detection

You may have heard in the news that the LIGO experiment recently detected a gravitational wave. Though I'm not an astronomer, the paper is a good read and mostly accessible. The detection of the ...
-1
votes
1answer
74 views

Is the flat curvature of the universe in the 5th dimension?

It is hard to imagine that the universe could have a flat curvature while I've read that it is at this moment the most likely. When you look around the universe is expanding in all directions, so it ...
1
vote
1answer
55 views

How early/late is the human race as intelligent life in the universe/milkyway? [closed]

In the history of the universe, there has been a time, where intelligent life had no chance to develop (e.g. in the early universe, when no habitable planets have formed) and there is a time today ...
1
vote
1answer
140 views

How did LIGO verify that the gravitational waves originated 1.3 billion years ago from two specific black hole collision? [duplicate]

So they finally found gravitational waves. That's cool and I trust is the case, but how did they confirm it originated 1.3 billion years ago and that two blackholes merging caused it and what ...
4
votes
1answer
157 views

Could a pair of binary black holes form within a star?

After the discovery of gravitational waves by LIGO last week the team behind the Fermi gamma-ray telescope released a paper that showed a soft gamma ray burst was detected only 0.4s after the ...
2
votes
2answers
102 views

Is phys.org/space-news reliable source?

I found this page: http://phys.org/space-news/ . It seems to me pretty good page with interesting news and so on and I like that it is free. But I noticed in comments people arguing about the validity ...
2
votes
1answer
49 views

What methods exist to calculate the ellipticity of galaxies

What methods exist to calculate the ellipticity of galaxies and what are their drawbacks? I have asked this question about ellipticity in the SDSS but I want to know about general methods for cases ...
28
votes
6answers
6k views

What did LIGO Actually See? (Gravitational waves discovery)

I am trying to find an original video/image of what LIGO actually saw, but all I can find is artist renditions of gravitational waves.
2
votes
2answers
128 views

Could gravity waves be used to confirm the existence of a ninth planet?

Shortly after the news of the discovery of gravity waves, my physics professor explained the significance of the discovery by comparing it to a medical X-ray machine. He said that gravity waves can be ...
1
vote
2answers
69 views

visualisation of galaxy density

If I had a long stick that was millions of light years long, and with a width of about the Sun, and I then swiped it through the center of the milky way galaxy, what would the probability be of me ...
3
votes
1answer
84 views

Sundial (solar clock) in a binary star system

What would a sundial look like in a binary star system? What is the path drawn by the shadows? It probably depends on the system, the sizes of the stars, their distance... If you know a binary star ...
4
votes
1answer
36 views

Problem with denoising the BICEP2 data?

This question pertains to this article which talks about why the BICEP2 measurements of B-mode polarization in Cosmic microwave background radiation turned out to be noise from galactic stardust. They ...
0
votes
1answer
29 views

Angular distance/apparent separation between AE Aurigae and Orion's belt

The title perhaps gives the question away, but would anyone know/be able to roughly approximate the angular distance/apparent separation between AE Aurigae and Orion's belt. I have the value of $42^\...
1
vote
1answer
81 views

The effect of gravitational wave is like tidal forces?

What would happen if a strong gravitational wave passed through a human body or any other kind of material? The shape of the human body would change? Would the human body be distorted apart? If ...
2
votes
1answer
67 views

How far should the source be, for the gravitation waves to be visible on Earth?

If I understand it well enough, gravitational waves cause ripples in the space-time fabric. To our eyes, that would look like those rippling-effects on amateur videos. Where does a source have to be,...
0
votes
2answers
38 views

Reference for broader spectral lines?

I'm looking for some reference listing spectral lines outside the visible spectrum. (In particular, I'm looking for an element or compound that emits strongly in the 700-900nm range.)
0
votes
1answer
31 views

Minimum Mass Solar Nebulae Scaling Factors

I'm attempting to build a MMSN, I've been trying for about... a week to get an intuition on the scaling factors for calculating the mass of the disks, I'm not entirely sure how to think about it. I ...
4
votes
1answer
56 views

How to determine the ellipticity of galaxies in SDSS

What is the best approach to determine the ellipticity of galaxies in the SDSS DR12. I have read this page. Are those really good methods? Do flux-weighted second moments (as given in the stokes ...
1
vote
2answers
69 views

Why can't different regions of the universe be the same as they have the same origin?

The horizon problem states that because of the speed of information can't be faster than light and the distances between far regions are too big there is a problem because they look quite the same. ...
0
votes
0answers
11 views

SDSS ImgCutout webservice returns black image for dr12

The SDSS (Sloan Digital Sky Survey) ImgCutout webservice should return jpeg images for a given field that is defined by the parameters. The service can be tested here: http://skyservice.pha.jhu.edu/...
0
votes
1answer
70 views

Does the event horizon of a black hole increase or decrease by adding mass?

So a black hole is a something that has enormous gravity, therefore mass accelerates faster towards it. But if the black hole double it's mass, will it's event horizon increase in length , or will it ...
1
vote
1answer
66 views

Why is there a difference between the cosmic event horizon and the age of the universe?

According to wiki the cosmic event horizon is 5 Gpc but the age of the universe is about 13,7 billion years. Usually light from far galaxys needed at most 13,7 billion years to reach the earth so the ...
5
votes
2answers
163 views

Why when we look through a telescope in space, do the billions of stars not block our view from seeing further?

I know that we are able to "see back into time" by looking very far away through telescopes such as the Hubble telescope, but my question is, wouldn't you run into at least a couple of stars that were ...
3
votes
1answer
56 views

What effect does the Moon have on the near Earth asteroid population?

Does the big (0.012 Earth masses) Moon of Earth clear away NEAs, Earth orbit crossing asteroids, in a significant way? Venus and Mars don't have large moons, do they therefore have larger or smaller ...
4
votes
1answer
98 views

Have we seen a black hole?

Have we actually seen a black hole out there? By "seen" I mean "recorded a em-spectrum image of gravitational lensing caused by object believed to be black hole".
2
votes
2answers
96 views

What would happen if those gravitational waves were much stronger?

What if those gravitational waves detected would be actually so strong that the distance of those mirrors moved would be larger? Not 1/1000th of proton but rather one millimeter, or one meter or even ...
2
votes
2answers
130 views

How to derive the redshift of GW150914?

We all know LIGO has detected gravitational wave(GW) directly. prl The LIGO team argue they detected the merger of two solar mass black holes($36M\odot+29M\odot-3M\odot$) at z=0.09. My questions ...
8
votes
1answer
165 views

Why can we detect gravitational waves?

Now that LIGO has finally measured gravitational waves using a huge laser interferometer, to me, the question remains, why was it possible? As it is explained in many news articles, gravitational ...
0
votes
2answers
60 views

What caused gravitational waves detected by LIGO?

I understand that in recent discovery gravitational waves have been detected. But knowing space time is not static it probably changes constantly in many places in the universe due to changes in ...
1
vote
0answers
33 views

Will we see gravitational waves from the big bang? [duplicate]

This is almost identical to an unanswered question already asked, but I want to put it a different way. The announced LIGO event was from a localized source. I assume that gravitational waves from the ...
4
votes
2answers
123 views

Why do Earth and moon move apart but binary black holes move closer?

According to the accepted answer on Is the moon moving further away from Earth and closer to the Sun? Why?, the moon is receding from Earth because tidal forces and friction cause energy to be lost. ...
0
votes
0answers
17 views

How the magnetic field and the rotation of the planets and the sun inside our planetry system are related

Coming from this question Are there collected data about the direction of rotation of black holes and the direction of the magnetic field? I want to know: How the magnetic field and the rotation of ...
0
votes
1answer
193 views

Is the Earth Really Spinning? (honest question)

Most people consider it common knowledge that the Sun's "movement" in the sky is only perceived due to the Earth's "spin and movement". Based on this, you'd think that the stars in the night sky (...
1
vote
0answers
50 views

Relationship between absolute magnitude of a star and its luminosity?

Why does this relationship involves the absolute magnitude of the sun and its luminosity? How to derive an expression relating the absolute magnitude of a star to its luminosity? So according to the ...

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