6
votes
3answers
100 views

What is the ultimate fate of a cluster of galaxies?

We're fairly aware clusters of galaxies drift apart due to space expansion, which will drive them out of each other's cosmic event horizon eventually, leaving them separate, alone, each a single ...
5
votes
0answers
39 views

Is there a paper on galaxy mergers in clusters of galaxies?

I'm looking for something to cite about galaxy mergers in clusters of galaxies. I need numbers on the frequency of mergers in the outer parts of galaxy clusters vs. the cluster center. In the center ...
0
votes
1answer
80 views

Contradict the expansion of the universe?

Lets say that we observe in a distant galaxy cluster, which in all the galaxies move far away from us. and here we see in the same cluster a galaxy that move away from us in a much lower velocity ...
7
votes
2answers
113 views

How are Galaxy Super Clusters Generated

I have seen pictures of clusters of galaxies, usually used in regards to theories of dark matter and galaxy formations. One of the most famous ones has the perceived shape of a stick-figure. If I am ...
2
votes
0answers
10 views

Estimating the tangential and cross component of the galaxy's shear using Gnomonic projection

I would like to know how I can estimate the tangential and cross component of the galaxy's shear using Gnomonic projection of the right ascension and declination ...
2
votes
1answer
19 views

Beta profile fit of Virgo cluster gas?

I'm looking for the parameters $r_c$, $\rho_0$ and $\beta$ in a $\beta$-profile fit of the Virgo cluster's ICM density. I just can't find a reference for it. Unlike for Coma (Abell 1656) where it's in ...
1
vote
2answers
39 views

Fate of the Spiral Arms of the Milky Way and Andromeda

In a few billion years, the Milky Way and Andromeda will collide. Chances are, there won't be many spectacular stellar collisions, and there's a pretty good chance that the Solar system (and most ...
0
votes
1answer
40 views

Thought experiment about the outskirts of the universe

Suppose I aim at some object that is 13 billion light years away from Earth. Let's assume I have a twin that pilots a ship that travels in infinite speed, meaning that he can reach that object and ...
8
votes
3answers
343 views

Questions about spiral galaxy arms

I have 2 questions related to spiral galaxies. Firstly, how did the arms form? Why would the stars accumulate into those specific areas? And secondly, why are they still intact? The inner parts of ...
0
votes
1answer
19 views

Mechanism for Brown Dwarf Fusion

I've read (at here, among other places: http://deepblue.lib.umich.edu/bitstream/handle/2027.42/55288/index.html?sequence=1) that during the Degenerate Era, star formation will end and the last stars ...
-1
votes
1answer
10 views

Could the universe have evolved differently?

Given the initial conditions at the Big Bang, could our universe have evolved any differently? In other words, did the initial conditions predetermine every stage in the evolution of the universe to ...
6
votes
1answer
91 views

Is the Hubble Ultra-Deep Field image representative of the entire sky?

The Hubble ultra-deep field image is a photograph of an area of sky equivalent to a 1mm x 1mm piece of paper held a metre away from the eye (one thirteen millionth of the entire sky). It contains an ...
2
votes
2answers
50 views

Why aren't the farthest objects close to each other?

The last years we find some objects like this : MACS0647-JD which are more than 13 billion light-years away from us. This means that the picture we get was created only some million years after the ...
7
votes
1answer
142 views

Determining effect of small variable force on planetary perihelion precession

Is there an analytical technique for determining the effect of a small variable transverse acceleration upon the rate of aspides precession (strictly not a precession but rotation of the line of ...
0
votes
0answers
13 views

How LOFAR pass through the ionosphere?

The LOFAR project open a new window in the universe's study because it allows to receive low frequences of the universe that we could not get because of the ionosphere. But I'm wondering how can ...
5
votes
1answer
31 views

How to identify stars in photographs?

I can look at a star chart and identify things like constellations in the sky. But if I take a picture with my DSLR camera (35mm with a decent zoom lens, no astronomy specific optics), I run into ...
7
votes
2answers
121 views

With gravitational lensing, is it possible to mathematically compute the correct image of the galaxy that is being distorted?

There's been another report of gravitational lensing in the news. Wikipedia has a good image of an example of gravitational lensing taken by the Hubble Space Telescope. This brings me to wonder ...
2
votes
1answer
31 views

Can the martian dichotomy (SIH) and the moon's formation (GIH) be related?

If we assume that the Single Impact Hypothesis regarding the martian dichotomy (wikipedia) and the Giant Impact Hypothesis regarding the Moon's formation (wikipedia) are true, then is it possible that ...
1
vote
2answers
105 views

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 ...
5
votes
4answers
86 views

The Existence of Natural Satellites in Geostationary Orbits

While browsing through Physics SE, I noticed a question about satellites in geostationary orbit (unrelated to the one I'm asking here), and for a moment I interpreted it as referring to natural ...
1
vote
2answers
96 views

How do black holes evaporate?

Will black holes evaporate, if they evaporate? When and why do they evaporate? What are the conditions for evaporation? Under what principle do they evaporate?
0
votes
3answers
89 views

What is the relative time difference between us and a star system in outer layer of our galaxy?

Just curious to know what will be the time difference between someone living on the outer layer of our galaxy and us, considering the known facts that Time is relative to gravity Our sun goes around ...
-1
votes
1answer
46 views

How to calculate planet positions in (Rāśi) zodiacal signs?

I want to calculate planet positions according Specific Date, Time and place (Latitude & Longitude). Further clarification: I will input Date, Time and Place (with latitude and longitude) and ...
1
vote
1answer
21 views

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 ...
1
vote
1answer
25 views

What is the exact position of the Large Magellanic Cloud?

I am not able to visualize the position of the LMC and have not found a satisfactory explanation... Can someone please answer it this way? Relative to a ray joining the Earth to the ...
6
votes
1answer
86 views
+50

Would bagging an asteroid destroy valuable science about it?

NASA has a plan called "Asteroid Redirect Mission option A". It would robotically put an asteroid of a few meters diameter in a bag and push it into reach of astronauts for thorough examination. 44 ...
1
vote
1answer
42 views

Original Hubble diagram units incorrect?

Figure 1 from Hubble 1929 has velocity with units of km. Is this just a typo or was there a reason the plot is printed this way?
2
votes
1answer
108 views

Are there stars that don't emit visible light?

Are there stars that do not emit any light in the visible part of the EM spectrum?
1
vote
1answer
55 views

What did I see streaking across the sky last night?

I was enjoying a casual naked eye view of the summer sky last night around midnight in a new jersey beach town. The sky was pretty clear for around here.The Milkyway was just visible and there was no ...
2
votes
1answer
66 views

Maximum Amplitude of a Lissajous Orbiting Object in a L4 or L5 Position

I stumbled on The Lagrangian points during some wikipedia reading. After looking at the gravity contours, I naturally come to the conclusion that the L4 & L5 should have a wave pattern and then ...
1
vote
1answer
37 views

World line coordinate finiteness

If you trace two particles' world line backwards in time, according to current theory, both objects should converge at big bang. Would both objects arrive there simultaneously? Another way of asking ...
11
votes
3answers
220 views

Why do (most of) the planets rotate counterclockwise, i.e. the same way the Sun does?

Referring to the mechanisms explaining the solar system formation and to the initial rotation of the gaseous cloud that collapsed, I understand easily why the planets orbit the Sun the same way this ...
5
votes
2answers
51 views
+50

Can the Gaia telescope detect small temporarily captured asteroids near its Lagrange orbit?

The Gaia space telescope is in a Lissajous orbit around the Sun-Earth Lagrange point 2. The orbit period is about 180 days and the size of the orbit is 263,000 x 707,000 x 370,000 km. It has been ...
0
votes
0answers
14 views

Any results from the B-mode CMB polarization measurements?

Why is the relation between primordial gravitational waves of the early universe, and the minor polarization deviations of the cosmical microwave background? AFAIK the CMB is coming from the 300000 ...
5
votes
3answers
148 views

Why do astronomers like green laser pointers? [closed]

When I've been to Astronomy-nights for the public at the local observatory, they always used green lasers to point things out. Why is there such a preference for green lasers? What's wrong with red ...
2
votes
1answer
30 views

Time after sunset until star can be seen

Given a star's apparent location and apparent magnitude, how how many degrees below the horizon must the sun be for the star to be visible to the naked eye for an observer on Earth at a specified ...
3
votes
2answers
39 views

Why do some celestial bodies have atmospheres, and not others?

Question is rather self-explanatory. An answer touching upon how/why atmospheres are formed in the first place would be ideal as well. An example of such astral bodies would be The Earth and it's ...
1
vote
1answer
34 views

Star System Formation questions

I'm making a game in which I'd like to randomly generate star systems. Which is cool. The trouble I'm having is working out exactly what limits I need to place on the generation. So far, the ...
7
votes
1answer
68 views

Can we see the Big Bang happen if we look far enough?

The observable universe is constantly expanding as more light from the Big Bang reaches us. This light has been travelling for billions of years, so we are looking at the universe as it was a few ...
1
vote
1answer
71 views

How many light years away is Earth from the closest outer edge of the black hole at the center of the Milky Way?

How many light years is Earth away from the closest outer edge of the supermassive black hole in Sagittarius A* at the center of the Milky Way? I don't mean the distance to the center of the galaxy, ...
1
vote
1answer
37 views

Which spiral arm of the Milky Way is Kepler-62 in?

I am trying to find out which spiral arm of the Milky Way the star Kepler-62 and its planetary system are in. All I can find by Google searching is that it is part of the Lyra constellation, but I ...
3
votes
1answer
59 views

How did the reionization epoch make the universe “transparent”?

I've been reading about the reionization epoch of the universe, and it isn't entirely clear to me. As I understand it, very shortly after the big bang the universe was ionized, with the electrons ...
3
votes
1answer
79 views

what is the farthest object we've been able to bounce signals off of to date?

I know people bounced lasers off of Venus and Mercury in 1960s in order to test the Shapiro delay. Since then, we've developed higher-power lasers and radio transmitters (Bolshakovo transmitter). ...
2
votes
3answers
66 views

Are there standard algorithms and procedures for creating unique sky maps based on latitude/longitude/date/time?

I am trying to build an astronomy app that will use the user's latitude and longitude, along with the current date and time, to create a 3D view of the celestial sphere as seen based on that data. ...
1
vote
2answers
102 views
10
votes
2answers
126 views

Will an observer falling into a black hole be able to witness any future events in the universe outside the black hole?

I know someone or something sucked into a black hole could not survive, but is the bending of light so immense that an observer falling into a black hole will be able to witness any future events in ...
2
votes
2answers
36 views

Can solar luminosity & activity be predicted?

Can a star's luminosity and its activity, solar flares and sunspots, be predicted? If so, with what accuracy & precision?
2
votes
1answer
25 views

What are possible methods of discerning a starburst AGN composite galaxy?

I'm currently working on an independent project that involves discerning starburst galaxies that are themselves within active galaxies. I would assume radio observations would be best to discern star ...
2
votes
1answer
70 views

What's an order-of-magnitude main sequence star look like?

I'm looking for a very rough, order-of-magnitude approach to the main sequence. What I mean is, I have a spherically-symmetric hydrogen distribution. I'm looking to get a rough approximation for ...
1
vote
0answers
60 views

Multiple apparent lunar eclipses last night

I saw something very strange last night that I'm hoping someone can help me explain. I was sitting on my roof with a night-cap at about 3am last night. The moon, about the last quarter, was low in the ...

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