# All Questions

9,781 questions
Filter by
Sorted by
Tagged with
2answers
243 views

### Nuetrino interaction with plasma and electromagnetism [closed]

Following question enter link description here After watching the Thunderbolt Project on Youtube I have a very very very fresh perspective on the universe - the electric universe. From the electric ...
1answer
163 views

### Time dilation on an object circling earth

How would a receiver on Earth hear a radio transmission from an object circling earth at 99% of the speed of light for 24 hours. The transmission from the object circulating would be non-stop. ...
1answer
524 views

### Asteroids between Mars and Jupiter

Is the cluster of asteroids between Mars and Jupiter two dimensional as seen in every model of solar system shown in books or television? Or is it three dimensional as i think it should be?
1answer
2k views

### What distance has the moon been from earth at the closest?

For every year, the moon is orbiting further away from earth. What distance has the moon been from earth at the closest?
2answers
131 views

### Neutrino interaction with dense molecular structures

Would dense molecular structures on heavier planets (crystalline or other compounds which are generally unknown to us) allow neutrinos to pass through as easily as on Earth?
2answers
554 views

### How many minutes does a sundial change every day?

I'm planning to create a sundial in Ghana (10° 28.852', 0° 26.032') in July 2014. I will stay there for about 3 weeks. Do I need to adjust the numbers anywhere in these 3 weeks? I know the shadow's ...
2answers
267 views

### Length contraction of a star

Something moving toward or away from us will be contracted in length according to special relativity. As the M31 galaxy is moving toward us at great speed it's "depth" should appear slightly ...
1answer
93 views

### Recommended papers

I am highly interested in how the moon originated. Theories suggest that the moon is a chunk of the earth, or rather, both were at one point one celestial body. Is there any literature out there with ...
1answer
209 views

### What if the black hole in the center of the galaxy grew faster?

Imagine that hypothetically the black hole in the center of the milky way gradually increased in mass by for example 50% every year. That is exponential increase in mass. Which visual effects would ...
2answers
119 views

### What happens to the energy from a GRB?

A gamma ray burst produces somewhere around 1044 J of energy, according to Wikipedia. Only a small portion of that energy will be absorbed by other objects. The rest of that energy will go on to ...
1answer
2k views

### Can I see “my own hand” in the void space?

If I were floating in a void (far away from any galaxy or cluster), would the light from these objects at such distances be enough to see for example, my hand?
1answer
547 views

### Is it possible that we see our solar system as a star?

A few days ago I just read here that our galaxies (one of which we are part of) move or expand faster than light, And read here that light we see from stars is extremely old, maybe more than several ...
1answer
150 views

### Periodic behavior of Venus

After a couple months of watching a very bright Venus appear at dusk and set soon after the Sun, I've noticed that it seems to have temporarily disappeared to the naked eye. I used a virtual sky ...
1answer
185 views

### How to estimate age of asteroid family Erigon

I have one problem: On picture below we can see Erigone family asteroids in plane semimajor axis - absolute magnitude. Based on V-type as a consequence of Yarkovsky effect, estimate age of this ...
3answers
1k views

### Are we made of the stuff of one star or more stars?

[T]his coincidence enabled stars in the late stages of their lives to turn helium into carbon, oxygen and most of the other atoms that you and I are made of. [...] [W]e're made of star stuff. Max ...
1answer
538 views

### Could the earth's atmosphere have been partially stripped by a passing rogue planet?

I am involved in the fight between palaeontologists and aerodynamicists on the theoretical flight capabilities of the largest pterosaurs (who reached their climax in the Cretaceous and then ...
2answers
251 views

### Could dark matter particles be unstable?

Is it possible that dark matter particles are unstable and the existing dark matter will decay in the long run and turn into hydrogen, for example? What would be possible mechanisms for such a decay? ...
1answer
726 views

### Did time pass more slowly in the past?

13 billion years ago, the universe was about 600 million years old according to many scientists. At that time, all matter in the universe would have to be closer, or in other words denser. Did time ...
2answers
89 views

### what is the highest throughput astronomy project in pixels?

I was having a discussing about big scientific projects with colleagues, and I postulated that astronomy is still one of the scientific fields with biggest projects per amount of data dealt with, ...
1answer
99 views

### Pictures of large galaxies

The Andromeda Galaxy is tens of thousands of light years in diameter. That suggests that the most distant stars in the Andromeda galaxy is up to tens of thousands of years "behind" in their orbit ...
2answers
255 views

### How often does Earth cross the galaxy regions with higher supernovae activity?

According to Summa Technologiae, a book by a Polish author Stanisław Lem that based his science fiction novels on scientific research of the era, the Earth crossed in the moment of forming of life the ...
2answers
889 views

### Amateur observing targets for binary star systems?

Are there any easily resolvable, binary star, observing targets visible from ~N40°? I'd like to be able to show, in one observing session, Mizar and Alcor (naked eye resolvable), another with ...
1answer
228 views

### Where can I find good places to watch stars? [duplicate]

Where can I find good places to watch stars near me? I live in Leicestershire, England and am looking for good places to watch the sky nearby.
5answers
442 views

### Orbiting around a black hole

Is it possible (for either a satellite or a planet) to orbit around a black hole? Do they attract everything around themselves into the center? Or they just affect gravitational force just like stars?
2answers
751 views

### Will new stars stop forming at some point of time?

New stars keep forming in the universe thanks to all the nebulae. Now, we need Hydrogen to form stars and there would a time when all the hydrogen will get exhausted, and no more star formation will ...
1answer
54 views

### In India, what is the best time to view the geminid meteor shower in 2013

As of the time of writing this question, the meteors should have appeared, but so far I haven't seen any. What time would be the best to view them?
1answer
965 views

### Emulation of an Orrery

Orrery is a clockwork model of the solar system. I am trying to emulate one in 2D. Now, to emulate, I need to know what goes on inside. Can someone please explain the basic principle behind the ...
1answer
136 views

### Age and relativity [closed]

This is a question, where I start with some assertions: Try to consider the universe as a four-coordinate system, x,y,z,t where t is time and where we view a change in t as a change in position, and ...
1answer
127 views

### How can the life time of a multiple star system, such as for example the trinary system PSR J0337+1715 be derived?

As for example explained at the beginning of this blog post, the trinary system consists of a millisecond pulsar ($1.438$ times the mass of the sun) orbited by two white dwarfs. One of the white ...
3answers
591 views

### Why are planets spherical?

I am a complete novice when it comes to astronomy, but someone asked me the above question casually. It seems as though planets are all roughly spherical, whereas other celestial bodies aren't ...
2answers
237 views

### Does gravity propagate?

Gravity is sometimes described as a curvature in space-time. Due to relativity, doesn't this imply that gravity doesn't propagate? A thought experiment. If you are moving toward a black hole, this ...
1answer
928 views

### When we say a galaxy is 200 million light years away, does this account for the expansion of space in the time it took it's light to reach us?

When we see a distant galaxy, the light we are watching started it's journey millions of years ago. In all that time, space has been expanding, so if the initial distance was A, right now the distance ...
3answers
471 views

### Heavy star and redshift

A heavy star should look redshifted, due to gravitational time dilation. How is that incorporated into the calculations of distances to the stars, or is it negligible? How about an entire region of ...
1answer
422 views

### Do galaxies have a preferred orientation?

This article: http://physicsworld.com/cws/article/news/2011/jul/25/was-the-universe-born-spinning asserts that the universe was "born spinning" and that there is a preferred rotation direction for ...
2answers
2k views

### How does angular resolution of a telescope translate to its parallax precision?

We can often read in the scientific and also more casual reader literature and articles about the angular resolution of various telescopes and other optical equipment, be it ground based or onboard ...
2answers
153 views

### Is the discovery of Alien or Extra Terrestrial Life a function of the science of Astronomy?

Is the discovery of Alien or Extra Terrestrial Life a function of the science of Astronomy? When i read astronomy articles on the search for new Planets or discussions on Mars a lot of the topic is on ...
1answer
302 views

### How can satellites be safe in the atmosphere when there are so many asteroids coming in?

How can artificial satellites be safe in the atmosphere when there are hundreds of tons of dust and asteroids coming into earth's atmosphere everyday? What is an orbit of an artificial satellite? At ...
1answer
502 views

### Could something temporarily break the Moon's tidal lock?

Would it be possible for something to cause the Moon to start rotating at a different rate, breaking its tidal lock with Earth, without ripping it apart? If so, would the Moon's tidal lock eventually ...
1answer
972 views

### How does gravity affect the wavelength of light?

If, hypothetically, me and my rocket powered flashlight were falling straight toward the center of a black hole. The flashlight is a few kilometers behind me in our travels toward the center of the ...
1answer
80 views

### Martian Brother [closed]

According to some documentaries History and Discovery, fossils have been found in a meteorite that fell to earth. This meteorite came from Mars. It is possible that the Martians always try to be ...
1answer
196 views

### The life course for a massive star from birth to death using the HR Diagram

could you explain to me the life course for a massive star (30-40 solar masses) from birth to death using the HR Diagram (by showing key events in its life on the HR Diagram)? thanks
1answer
898 views

### If we were to see the Sun with our naked eyes from the Orion belt, would all planets be encompassed inside the star? Is this calculable?

When we see a star it looks much bigger in diameter to us than it really is, this picture (extracted from here) explains what I mean: Notice that the point we see in the skynight, represented by the ...
1answer
119 views

### What does observational evidence say about the number of protoplanets believed to exist in the early solar system?

Currently, the solar system has 8 major planets, a handful of dwarf planets and a plethora of asteroids, comets and natural debris, and of course, a rather locally dominant star (the Sun). There are ...
2answers
3k views

### How to calculate the altitude of the Moon?

With the known latitude coordinate of the observing position, how to find the altitude of the moon when it is high, i.e when it crosses the local meridian?
1answer
212 views

### How Does Cosmology Constrain the Number of Neutrino Species?

I've asked this question already on the Physics SE, but I felt it would be worth posting here as well. I know that based upon theories of structure formation cosmologists can constrain the sum of the ...
2answers
3k views

### How does a telescope measure parallax angle?

I know how stars' distances are measured by using parallax, but I want to know how the actual telescope measures the parallax angle. Any helpful links/ explanations are needed.
1answer
59 views

### (Sound) Echo from X takes 5-7 days, [closed]

Hey I want to describe an event A happening roughtly 5-7 after event B. I'd like to describe it as the 'A happened after the sound of B echo'd off X', where X is recognisable space thingy... (I'm ...
2answers
157 views

### What does the term alien planet actually refer to?

This article left me wondering what do they mean by the term alien planet? Aren't all planets simply alien by default, or do they mean planets outside our solar system are alien? Do they mean there is ...
1answer
184 views

### How do astronomers find interesting events?

I always wondered how those tiny dots representing moving stars or whatever forming an interesting event (supernova explosions, stars being sucked into black holes etc.) get caught in the huge solid ...
1answer
813 views

### Latest sunrise/earliest sunset out of phase with solstice?

Everybody knows that the shortest and longest days of the year occur on the solstices. However, examination of sunrise/sunset tables shows that the maxima and minima of sunrise/sunset times are ...

15 30 50 per page