1
vote
2answers
89 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? ...
3
votes
2answers
34 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, ...
2
votes
2answers
71 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.
3
votes
1answer
62 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 ...
1
vote
2answers
48 views

Can redshift be measured using fourier?

Are there pictures that contain high enough dynamic width, so that amateurs can use fourier spectrum analysis to observe the redshift themselves? I know pictures usually are encoded using RGB and/or ...
4
votes
1answer
67 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 ...
8
votes
2answers
184 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 ...
0
votes
1answer
102 views

Can you identify this telescope in a desert? [closed]

It should be in a desert. 5-15 similar lens cones are binded together,small size(about 30 cm?),same direction. The purpose is to find exoplanet? It is like WASP below. It is in a desert and lower ...
13
votes
3answers
240 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 ...
5
votes
1answer
101 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 ...
9
votes
1answer
132 views

Where is all the antimatter?

The universe supposedly started off with equal parts matter and antimatter and they are said to annihilate each other. Also, nature is famous for it's balance between everything. So all we see is ...
6
votes
1answer
50 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 ...
0
votes
1answer
67 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 ...
7
votes
1answer
129 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 ...
5
votes
2answers
41 views

apparent size of an astronomical body

What's the name of the measure of apparent (visible) size of a body? e.g. the Sun and the Moon appear to be roughly the same size, despite the Sun being vastly bigger - because the Moon is much ...
7
votes
2answers
707 views

Why can we sometimes see the moon during the day?

At some points in the year, the moon at my location can be clearly visible during the day. Why is this? If it is any help, I live in Alberta, Canada.
5
votes
3answers
160 views

Does gravity slow or speed light up?

The speed of light in a vacuum is presumably the fastest speed possible. if gravity bends the course of light, does this imply that gravity the retards light so it is moving at a slower speed? If ...
3
votes
1answer
59 views

Rotation and relativity

When a planet is spinning around its own axis, it has an effect on the trajectory of its satellites. I believe it is called frame dragging. Spin increases the kinetic energy of an object, ...
5
votes
2answers
145 views

Why do we have the cosmological constant?

Since the cosmological constant is not required to explain that the universe seem to be expanding, why do we have it? What other factors cause us to have that constant? Background: Without the ...
5
votes
1answer
112 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 ...
4
votes
2answers
65 views

What is the relationship between the focal length and f number of a telescope compared to a guide scope?

How do you determine the optimal length of a guide scope for a given imaging telescope? I imagine it would have to take into consideration the pixel size of the guide scope, but would the aperture ...
7
votes
3answers
144 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 ...
5
votes
3answers
66 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 ...
3
votes
2answers
63 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 ...
5
votes
2answers
39 views

Are nebulae only visible from a distance?

There's plenty of data about the density of nebulae, and obviously they're pretty thin. This is space, after all, and these things are really, really big. But I'm wondering about the practical ...
3
votes
1answer
59 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 ...
4
votes
2answers
188 views

How to plot orbit of binary star and calculate its orbital elements?

I have a set of dates, position angles ($\theta$) and angular separations ($\rho$) for visual binary star. For example: ...
5
votes
1answer
88 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? ...
4
votes
2answers
88 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 ...
0
votes
1answer
48 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 ...
4
votes
2answers
113 views

How does light affect the universe?

When light is emitted by for example a star, that star loses energy - which causes it to reduce its gravity. Then that energy begins a journey for potentially billions of years, until it reaches some ...
6
votes
1answer
92 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 ...
2
votes
1answer
76 views

Black Holes emitting Hawking radiation

I've read that even light cannot escape from black holes. The speed of light is theoretically predicted to be the escape velocity of a black hole. I've also read that the general notion that nothing ...
5
votes
2answers
85 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.
0
votes
1answer
45 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 ...
7
votes
1answer
123 views

Where is Voyager 1 (or 2) going? In which direction?

Knowing it has exited the solar system, is it traveling in the direction of the center of the galaxy, away from it, orbiting it, or maybe even going perpendicular from the disk-shaped galaxy?
6
votes
1answer
72 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 ...
7
votes
2answers
275 views

Why don't we see the galaxy center?

When we look at the sky, and see the Milky Way, we mainly see a band, with no real center. On a more accurate picture we can guess the center of the galaxy (see this picture), but we still don't see ...
3
votes
2answers
251 views

What is the physical, geometric shape of the universe?

I'm not asking about theoretical ball, vs saddle, vs flat surface which is just a metaphor with 2D space. It's hard to say as we see very little of it, and we see them in the past because light ...
3
votes
1answer
62 views

What does it mean for a black hole to “evaporate”?

It says in this Wikipedia's article: Entropy, however, implies heat and therefore temperature. The loss of energy also suggests that black holes do not last forever, but rather "evaporate" slowly. ...
4
votes
1answer
57 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 ...
4
votes
1answer
108 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 ...
4
votes
1answer
125 views

What is the fastest spinning rotation of a Neutron star?

What is the fastest spinning rotation of a Neutron star? I have heard that Neutron stars have a specially fast spinning rotation. What is the fastest?
5
votes
1answer
88 views

What Is The Great Attractor?

I've heard that there is something called the Great Attractor which seems to have some kind of gravitational influence on objects in the Universe. Is this some kind of theoretical notion posited in ...
6
votes
1answer
64 views

What is a Barlow lens?

I am looking to buy a Celestron 21023 FirstScope 76 Telescope, which is quite inexpensive, and it has good reviews on Amazon. One thing that many reviewers have said is that the two lenses that it ...
11
votes
1answer
156 views

Our galaxy, the Milky Way, forms part of a galaxy group called The Local Group. What are the parameters that dictate what a galaxy group is?

Are there different classifications or just the one? How does our galaxy group compare with others?
3
votes
0answers
139 views

What skills would a software developer need to get a job in space research or exploration organization? [closed]

I am in the field of software programming. What skills should I brush up and gear up to get a job in space exploration and the observatory industry? What are various job profiles in terms of software ...
4
votes
1answer
137 views

Telescope buying guide for a beginner in India

I am located in the southern part of India and am looking forward to buy a telescope to gaze up to look ay farther planets, moons in our solar system and take pictures. How should I go about getting a ...
3
votes
1answer
74 views

Which planet or moon has all resources that can be used to sustain life in a controlled biosphere? [closed]

Now that we are making it to Mars, continuing onward, in an effort for humanity to civilize other planets, not just setting up residential colonies, but to mine minerals and carry on geological and ...
6
votes
1answer
77 views

Can Doppler shift make colors of two stars at same distance different?

As you know, Doppler effect can change the wavelength of the light. Suppose there are two stars at same distance and same temperature. If one star is receding and the other star is approaching, their ...

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