0
votes
2answers
94 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 ...
1
vote
1answer
35 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
3
votes
2answers
106 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 ...
3
votes
2answers
399 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
33 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
218 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
159 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!!
-1
votes
3answers
72 views

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

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 ...
2
votes
1answer
87 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 ...
3
votes
1answer
110 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
143 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 ...
1
vote
1answer
57 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 ...
8
votes
2answers
159 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 ...
1
vote
1answer
177 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.
1
vote
1answer
79 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 ...
4
votes
1answer
192 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
89 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 ...
1
vote
0answers
41 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
52 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 ...
2
votes
1answer
43 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, ...
1
vote
0answers
46 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).
5
votes
2answers
392 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?
4
votes
2answers
104 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?
3
votes
0answers
49 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 ...
7
votes
1answer
141 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 ...
2
votes
1answer
355 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
2answers
58 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
71 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 ...
3
votes
3answers
322 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?
8
votes
3answers
5k 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?
1
vote
0answers
66 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
74 views

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 ...
2
votes
2answers
103 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
137 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 ...
3
votes
1answer
61 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?
2
votes
1answer
137 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. ...
1
vote
1answer
60 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 ...
0
votes
1answer
39 views

Does the universe prefer a velocity?

As I understand it, the distribution of matter is roughly homogeneous across space -- anywhere I stand in the universe, there will about the same amount of matter in every direction around me. Is the ...
2
votes
0answers
31 views

Available data on the Milky way around 1920

In a book by Alexander Moszkowski, there is an Einstein quote about a hypothetical size of the universe (100 million Light years). Moszkowski claims that Einstein had deduced that from the ...
2
votes
1answer
32 views

How can I use Polar Alignment to find objects in the sky?

I have a six inch telescope on an equatorial mount and I've been struggling to use the mount properly. For a couple months now, the only strategy I've used is just 'point and look.' I've watched some ...
6
votes
4answers
430 views

Does Sun have a reflection on Earth?

The new Google Maps1 presents an actual view of Earth, with the current position of Sun illuminating half part of Earth in real time. It is quite an exquisite view. My question is based on the ...
1
vote
1answer
98 views

What was the orbit of the meteor that impacted the Moon on 2013 September 11?

On 2013 September 11th, a meteor impacted the Moon leaving a 34-meter crater. So far the only info I've found was from youtube (https://www.youtube.com/watch?v=zCFDkj2JtyA) and this site: ...
3
votes
2answers
53 views

What is the force of a CME on objects in space?

I've been reading a little bit about coronal mass ejections lately and they seem really interesting, and they cause a lot of amazing things to happen. However, one thing I haven't seen is the physical ...
3
votes
1answer
42 views

How do we convert other waves of the EMS to visible light?

So I just had a quick question and I was wondering how we convert other waves of the electromagnetic spectrum to visible light waves. For example we use X-ray's or radio waves to see things in space ...
-1
votes
1answer
71 views

Apollo Moon Landing [duplicate]

Can there be any truth to the rumour that the Apollo Moon landing in 1969 was staged ? I dismissed this rumour as being nonsense but today on the news I was surprised to hear that the head of the ...
6
votes
4answers
330 views

Is it possible to use Hubble Telescope to observe Earth in the past?

We can observe many astronomical objects and structures beyond our solar system, however our observations are as the objects appeared in the past due to the speed of light. My question: "Is it ...
1
vote
1answer
91 views

Question about total absolute magnitudes of galaxies - negative or not?

I have seen this in a couple of places, but when the authors in the paper - http://chandra.as.utexas.edu/~kormendy/kfcb-accepted.pdf - wrote: "All 10 of our ellipticals with total absolute ...
3
votes
2answers
66 views

Pulsars: How do astronomers measure minute changes in period (~picoseconds per year)?

I've been to some talks that mention how stable the period of a millisecond pulsar is over long periods of time. Recently, it was mentioned that astronomers have calculated the change in period over ...
0
votes
1answer
69 views

How accurate are rederings of something entering Earth's atmosphere?

Supposedly how accurate is it when you see a movies showing something entering Earth's atmosphere traveling 1 mile to 10 miles an hour or barely at all but skinning the atmosphere they show it heating ...
2
votes
1answer
153 views

How does the Grand Tack Hypothesis explain how Jupiter formed inside the frost line?

The Grand Tack Hypothesis states that Jupiter formed at roughly 3.5 AU from the Sun, then interacted with a large portion of objects in the Solar System before settling into its current orbit. Yet as ...

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