0
votes
0answers
1 view

Can we spot a gray-goo exoplanet?

How would look an earth-like planet eaten by nano-machines? I guess there must be some properties we can assume from different nano-machine scenarios - strange size, too uniform landscape (a perfect ...
0
votes
0answers
11 views

How is expansion different from contraction?

For example, two space ships cross the event horizon. There would be a period of time where space is 'expanding' correct? I mean, the lead ship would always be accelerating faster than the one ...
2
votes
0answers
24 views

Why didn't we have inflation when the theory of everything and GUTS broke symmetry?

Inflation seems to have occurred when the symmetry breaking of the electroweak occurred. But do we know of any reason why we did not have inflation when gravity separated from the other forces or ...
0
votes
0answers
18 views

How does the Higgs field relate to the Yang-Mills fields and gauge theories in general?

It is very confusing. Is there an easy explanation that will tell me how these differ or what the difference is?
-1
votes
1answer
54 views

Stability of solar system

My question is simple: Is the Solar system stable? You can see this Wikipedia page. Edit: Sorry, because i think my question is more about mathematics and classical mechanics of planets in ...
1
vote
1answer
36 views

What is the air pressure in the heliosphere (Sun's atmosphere)?

Specifically, I am wondering what the pressure is at a distance of around 1 AU. Does it it decrease quadratically with distance?
0
votes
0answers
23 views

Why did Kepler Telescope's Reaction Wheels fail?

I was just reading about the Kepler telescope and how it uses reaction wheels to finely control orientation, much like Hubble. Reaction wheels seem like very simple devices with only one moving part: ...
-1
votes
0answers
18 views

How can I use Buchdahl's equation of state with analytic solutions to Einstein's equations to solve for the mass-radius relation analytically? [on hold]

I am trying to model a neutron star as a polytrope based on the non-relativistic equations of stellar structure. Post continued below since I have less than 10 reputation.
-1
votes
3answers
46 views

Does the sun move

I'm curious, does the Sun actually move? The concept behind the question is, if you wear a shirt and you move, does the shirt actually move? Like the Solar system orbits around the Milky Way, but does ...
-1
votes
1answer
40 views

what is the time mentioned after date (1962-07-03+02:00) the +02:00? [on hold]

i was retrieving a some personalities birthday date through computer programming when i retrieve a person's birthday the result was ...
-1
votes
0answers
14 views

Dull, Red, Slow Moving, Meandering Meteors?

+Localfluff I've seen three to date. One 2-3 years ago the last two March 2015 5 minutes apart! Naked eye 11:00pm or so from Aviemore area of Scotland. First and biggest (pinkie nail at arms length) ...
1
vote
2answers
62 views

What causes horizontal and vertical lines coming out of pictures of stars?

What causes the horizontal and vertical lines coming out of pictures of stars, instead of them simply appearing as circles? For example, this picture from Wikipedia: .
0
votes
2answers
75 views

Accidental or deliberate? [duplicate]

We know the visual size of Sun and Moon from the Earth in our life time(!) are nearly equivalent. Now my question: this event is random or have a scientific reason? For example maybe there is ...
0
votes
1answer
22 views

Eclipse on the moon

What kinds of eclipse is seen by the person on the moon, when there is i)Solar eclipse on the earth and ii)Lunar eclipse on the earth
1
vote
1answer
55 views

How much larger would a star have to be to cause thermonuclear reactions if it was made out of mostly rock like Earth, instead of gases?

I assume it would have to be considerably larger since rock isn't as flammable as gases are? But it's also more dense to begin with.. Do we know of any suns that are made like this? Is it even ...
1
vote
2answers
88 views

How to calculate conjunctions of 2 planets

So, the recent conjunction of Jupiter and Venus seems to have spawned lots of excitement over this "rare" event. But what I can't figure out, is exactly how rare it is. And I've seen such conflicting ...
0
votes
1answer
26 views

Are mass extinction events more likely during meteor showers / passing through comet debris?

Meteor showers happen when Earth passes through the debris left by a comet in its orbit. Meteors are generally tiny, like snow flings or pebbles and don't make it to the ground as meteorites. But ...
5
votes
1answer
108 views

How can Halley's Comet be predictable?

How can we know that Halley's Comet is going to come again every 76 years? I understand that the comet has an orbit around the sun but how can scientists know that it won't be thrown off course for ...
1
vote
1answer
92 views

What is the brightest star (by absolute magnitude) that we can see by naked eye?

Is it Rho Cassiopeiae or Mu Sagittarii? I see in the Stellarium 0.13.0 that Mu Sagittarii have absolute magnitude -11.43!!
0
votes
0answers
23 views

What is the next planned mission that can discover life on another planet?

I've heard that we have a great shot at finding life on Mars if we just drill deep enough down to the surface to the water and detect if its sterile or not. Are there planned missions to do this? If ...
1
vote
1answer
45 views

How to find Exomoons?

How would we be able to detect Exomoons? We detect exoplanets by seeing if the light gets faint from a star, but could we really use the same method for determining if there is an exomoon around that ...
0
votes
0answers
29 views

Stellar mass database

I need a stellar mass database that also has the distance of the star/system from the sun. Can anybody tell me the name of such of database and where I can find it. I need to do a project on this. ...
2
votes
2answers
104 views

Does a week represent something in astronomy? [duplicate]

I know that a day represent the time for the earth to make a full rotation around its own axis and a year is the time for the earth to make a full rotation around the sun. But does a week represent ...
0
votes
0answers
27 views

How far away would a supernucleus comet be visible?

If an instrument like LSST quickly spots something as soon as it reaches magnitude 24½, how far away would a 60km first-time visitor from the Oort cloud be when it is spotted? I'm thinking that a ...
1
vote
1answer
45 views

Is the diameter of the observable universe a relative quantity?

The diameter of my observable universe is 90 billion ly measured in proper distance. But isn't lenght a relative quantity in the theory of Relativity? Could an observer moving at a different velocity ...
0
votes
1answer
17 views

When will the next summer solstice and a full moon coincide? What day?

What day will the summer solstice and full moon coincide? As far as I know the next time will be in 2016. I would like to know what day.
0
votes
1answer
39 views

What is the projection of Earth's axis on the sphere with the Sun in center (see explanation)

Seems like it is the most convenient SE community for this question.. Imagine the sphere, witch center is the Sun and radius is, say, ~1.5 distance from Sun to earth (in arbitrary time, precise ...
2
votes
1answer
38 views

How to calculate the limiting magnitude of Hubble?

I've found various sources on the web stating that the limiting apparent magnitude of the Hubble Space Telescope is about 31 or 31.5. Wikipedia lists that here and it has a cite to a pdf about it. ...
1
vote
1answer
67 views

Which is the shape of the sky?

I'm a software developer and I'm developing a planetarium and the first thing that I don't know is: What is the shape of the sky? First, I though that it is a semi-sphere, but searching on Internet I ...
0
votes
0answers
31 views

material exchange between a planet and its host

Of the exo-planets found so far, there is one that can exchange material much with its host? How to prove that? Io may be a good example, but it is not a planet.
1
vote
1answer
41 views

Dark Matter Detection

A paper appeared at the arXiv.org (in April or May) claimed that the writers have found the gamma rays emitted by annihilation of dark matter in a satellite galaxy of the Milky Way by examining the ...
1
vote
1answer
27 views

What to do after first year of amateur astronomy? [closed]

I have practiced astronomy as a hobby for a while now. I have an entry-level telescope (6-inch Newtonian). In addition to observing the night sky, I have been studying physics related to optics, ...
0
votes
0answers
31 views

Abbreviations for days of the week

Is there a set of standard abbreviations for the days of the week for use in astronomy? I couldn't find any reference to it in the The IAU Style Manual (1989).
4
votes
2answers
338 views

Are space telescopes completely out of the earth's atmosphere?

Is the Hubble Space Telescope, and every other space telescope for that matter, completely outside the Earths atmosphere?
1
vote
2answers
48 views

How/where to check where the Sun is (constellation)?

I would like to check in which constellation the Sun was in at some time in the past, any recommendations how to do that?
2
votes
0answers
40 views

If nothing can pass the schwarzschild radius, how can black holes even start? [duplicate]

From our point of view, no object can fall into a black hole in finite time. The object will seem to be more and more red-shifted to us, but it will never quite pass the schwarzschild-radius / event ...
5
votes
1answer
98 views

Has the great Andromeda Galaxy ever collided with any galaxies?

We know that the Andromeda Galaxy is moving towards the Milky Way and vice versa, so there will be a collision. Because of the vast space between the stars as they are defined will not themselves ...
1
vote
1answer
254 views

How long will it take Pluto to grow to planet size? [closed]

Pretty much everything in our solar system has collisions with smaller objects that lead to an increase in the mass of the larger. With Pluto being one of the largest things in the area of which it ...
-2
votes
0answers
36 views

What are Wolf - Rayet stars?

I learnt about various types of stars and objects from a recent hubble public lecture on The weirdest stars in our universe. I also explored about them in Internet. During this exploration, I came ...
2
votes
2answers
48 views

Is “Main Sequence” a temporal sequence?

Stars plotted by luminosity and surface temperature fit into patterns in a Hertzsprung–Russell diagram. A rough diagonal subset of this plot is called the main sequence. Is this in any sense a ...
0
votes
2answers
49 views

Star formation analogy

If I have understood correctly, stars form in big clouds of gas and dust that are pulled together by their gravity. And the stars are often ignited when something disturbs the cloud, such as a passing ...
1
vote
3answers
109 views

How does gravity interact with a photon?

If photon is mass-less and gravity can interact only with matter, then how does gravity alter the trajectory of light?
4
votes
3answers
166 views

What is the name of our Solar System?

what is our Solar System called rather than "the Solar System"? I've found "Sol System" and "Monmatia", too, but is there more to it?
0
votes
0answers
37 views

Why some stars appear to move differently when viewing device shakes

I was looking at Arcturus with a pair of binoculars, and noticed that when they vibrate due to my heartbeat, Arcturus seemed to move differently than the other dimmer stars. I started playing with ...
3
votes
2answers
63 views
+150

Is any meteorite known to come from a comet?

Comets are mostly icy but they should have some rocky components too, right? I wonder if there's any rocky piece of a former comet among collected meteorites. Is it possible today to identify a ...
1
vote
2answers
57 views

Metal rich or metal poor?

What does the image in the link mean? Are the stars in the halo high in metallicity or low? How about at the bottom by the disk? ...
4
votes
1answer
110 views

How do you calculate length of day in a multiple-star system?

How can you calculate the length of day for a planet (given a particular latitude and longitude on that planet) orbiting multiple stars? What about a planet that is orbiting one star, but that star ...
1
vote
1answer
52 views

Is metallicity low at the central region or nucleus of the Milky Way?

Is metallicity low at the central region or nucleus of the Milky Way? Does metallicity decrease or increase as we move from the center out to the edges of our galaxy?
1
vote
1answer
117 views

Name and language of symbol in astronomy book

I've been working on a programming project involving Peter Duffett-Smith's Practical Astronomy With Your Calculator (3rd Ed.), which has a large number of mathematical/astronomical formulas in it. ...
0
votes
1answer
49 views

Age of the universe vs. its contents

A couple of decades ago I read an article (could have been either Astronomy, Space, or Science News) that suggested the contents of the universe may be older than the universe itself. Of course, that ...

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