All Questions

3
votes
1answer
80 views

Is the expansion accelerating or Decelerating?

According to Hubble's Law, the farther a galaxy is, the farther it is moving away. But do we take into account the fact that we are actually looking in the past? For example, there are two galaxies A ...
3
votes
1answer
60 views

Does Tobler's First Law of Geography Apply to Star Composition?

There is a principle in Geography called Tobler's First Law of Geography which states that "Everything is related to everything else, but near things are more related than distant things." Does this ...
3
votes
1answer
32 views

Instrument aperture sizes on Hubble Telescope

When looking at the diagram of the focal plane of the Hubble Space Telescope I noticed that the aperture sizes of most of the scientific instruments are very small. They occupy a very tiny fraction of ...
3
votes
2answers
58 views

Where can I find a set of data of the initial conditions of our solar system?

As title suggests I'm in need of a set of data of our solar system. Similar to this http://bima.astro.umd.edu/nemo/archive/#iau25, specifically dubinsky milky way-andromeda data. I'm creating a ...
3
votes
1answer
90 views

Could an asteroid impact cause radioactive fallout?

Could a (regional or global) fallout of radioactive material be a "bonus" disaster effect of an asteroid impact? My reasoning for how such a scenario maybe could be possible: A) Some asteroids maybe ...
3
votes
2answers
80 views

Why is Mars considered the outer edge of the “goldilocks zone”?

In both books and documentaries I often see the Goldilocks Zone as described between Venus and Mars with the Earth "just right." This seems sort of ill thought out to me, because it assumes that ...
3
votes
2answers
94 views

Questions about time and space (from beginner)

To be honest my knowledge about astronomy and related physics is close to zero. However, since I studied math a bit, I would like to ask a couple maybe stupid questions, which I am curious about and I ...
3
votes
1answer
102 views

Which type of telescope should I make?

I am not very much interested in observational physics but I just like to look at the night sky. It gives me a lot of inspiration. So, i was thinking about making a telescope for basic observations. I ...
3
votes
1answer
66 views

What’s the object between the earth and the sun currently showing in Google maps?

If I select satellite imagery in Google maps and zoom out, the earth is shown in space. It shows light/dark regions correctly updated, but there’s an object between the earth and the sun. It looks too ...
3
votes
1answer
49 views

Sattelite's orbit

What is the maximum distance for a satellite to orbit the earth? Does earth's gravity has the impact on satellite? I do know that earth's gravity will never be zero and it's gravity is inversely ...
3
votes
1answer
264 views

How to get the longitude/latitude from solar zenith/azimuth?

How do I get the longitude/latitude from zenith/azimuth? Or how can I position my sun in a 3d application? code extracted from here ...
3
votes
3answers
276 views

Spotting the International Space Station (ISS)

Recently, I visited the NASA website which provides sighting locations to see the International Space Station (ISS). As we all know, we can even see ISS with the naked eye in a clear sky as a passing ...
3
votes
1answer
46 views

What happens to the shrinking universe in the presence of the pressure of Hawking radiation?

Black holes release Hawking radiation. Now assume that the universe after all collapses back again, bringing all matter to a single black hole. I assume that this would bend the whole space-time of ...
3
votes
1answer
60 views

How is the magnitude of a star measured?

How does one measure the brightness of a star?, I did not find anything on the internet.
3
votes
3answers
137 views

Why is the outline of a crescent moon brighter?

Some quick googling has given me the answer to whether seeing part of the moon that receives no sunlight is an optical illusion or not: it isn't. Earthshine lights the moon enough for the human eye to ...
3
votes
1answer
62 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 ...
3
votes
1answer
64 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. ...
3
votes
1answer
76 views

Coordinate transformations between reference frames in spherical astronomy

Suppose there are two observational frames of reference with origins $O$ and $O'$, respectively, separated by some constant distance. A body located at point $P$ has Cartesian coordinates ...
3
votes
1answer
148 views

How does a Bahtinov mask work?

For focusing the image of a telescope, one can use a Bahtinov mask. How does this mask work, and how did Mr Bahtinov get the idea to cut such a peculiar shape? Is it possible for me to design my own ...
3
votes
1answer
51 views

Exercise: 2D orbital mechanics simulation (python)

Just a little disclaimer beforehand: I have never studied astronomy or any sciences for that matter, so I am trying to fill this gap by self-education. Astronomy is one of the areas that has captured ...
3
votes
1answer
77 views

Is early life required for life?

I was watching the new Cosmos and Neil DeGrasse Tyson said something that made me go hmmm... He mentioned that the only reason that the Earth did not experience the runaway greenhouse effect like ...
3
votes
1answer
51 views

What is the shape and size of a gamma ray burst?

As I understand it, a gamma ray burst is created when a massive star collapses into a black hole. The poles of the black hole eject a massive burst of energy which we know as gamma ray bursts. So my ...
3
votes
1answer
26 views

Tools for creating a multiwavelength view of the sky

Not sure that this is the correct place to ask this question, but here goes. I am trying to find tools to accumulate image data (preferably in FITS format) on a given (RA, Dec)-coordinate of sky. ...
3
votes
1answer
22 views

Save current state in ds9?

After fooling around with a FITS file(s) (e.g. setting scale, changing color) is it possible to save the session such that there is a file associated with all those tweaks the next time I open it up? ...
3
votes
1answer
26 views

meaning of p-wave charmonia

What exactly does p-wave mean when referring to particles, like charmonia states. For example, see the following reference: http://arxiv.org/abs/hep-ph/9208254 My doubt is - p wave in scattering ...
3
votes
1answer
51 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 ...
3
votes
1answer
60 views

What is star composition after formation

Most descriptions of star ignition go something like... The star reaches a critical mass and ignites, blowing away the surrounding material. The most obvious question would be "Why are stars not all ...
3
votes
1answer
51 views

Potential Re-Capture of Rogue Planets

Rogue planets can be designated as rogue planets due to one of two possible scenarios: 1) the "rogue planet" formed as a sub-brown dwarf, or 2) the planet was ejected from its home star system. I want ...
3
votes
1answer
52 views

What are Flamsteed numbers?

Can you tell me about Flamsteed numbers? I just know that it is a specific number used for identification of stars. But what is the theory behind it? In what way is the number given to stars?
3
votes
1answer
52 views

How massive does a planet need to be to create gravitational lensing?

Is it ever possible for starlight to be distorted in a noticeable way from something as small as a planet? I'm guessing that the chances of this working are better on a dense terrestrial planet than ...
3
votes
2answers
49 views

What is the difference between a dwarf spheroidal galaxy and a globular cluster?

This Wikipedia article states that Segue 1 is either a dwarf spheroidal galaxy or globular cluster associated with our own Milky Way. I am wondering what the difference is between dwarf spheroidal ...
3
votes
2answers
173 views

What is gravity really?

What is gravity? I want to know more than it being simply the "mysterious force" that attracts things to earth. Is it a particle, a wave, or something else entirely?
3
votes
1answer
61 views

How would a planetary defence against comets work?

Mappings of practically all potentially dangerous asteroids is well underway. But comets seem almost hopeless to protect against. How far away are approaching comets detected today? How long time ...
3
votes
1answer
52 views

Space objects visible from earth

I recently saw the International Space Station without a telescope. Are there any other man-made space objects that can be seen using bare eyes?
3
votes
1answer
100 views

Is there another explanation, apart from the doppler effect, for the redshift observed in distant galaxies?

On episode 10 of the original Cosmos TV series, Carl Sagan mentions that some scientist don't agree that the redshift observed in distant galaxies is evidence of the big bang, stating that probably ...
3
votes
1answer
58 views

What method is used to calculate the 'quality' of a solar/planetary image?

What sort of algorithm is used to calculate the relative quality of an image, such as is performed by PIPP, Registax, or Avistack? Such applications take planetary or solar images and prior to ...
3
votes
1answer
46 views

What are the concrete technical arguments supporting the idea that the wave function of the universe can be written as partition function?

In this talk, the not yet settled down idea that the wave function of the universe could potentially be written as the partition function of a scale invariant statistical field theory is mentioned: ...
3
votes
1answer
82 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. ...
3
votes
2answers
83 views

Expansion again: where does the energy come from?

Is it sensible to ask for the overall increase in potential energy when looking at the baryonic mass in the universe moving away from each other, that is, moving against the direction of the force ...
3
votes
1answer
67 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 ...
3
votes
1answer
79 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 ...
3
votes
1answer
76 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 ...
3
votes
1answer
109 views

USNO moon images look quite different?

I visited: http://aa.usno.navy.mil/imagery/moon http://www.usno.navy.mil/USNO/time/moon-phase-images within seconds of each other, and saw two very different "current moon images": Is one of ...
3
votes
1answer
48 views

Why is there billowing dust in nebulae?

Why do some nebulae look like the billowing clouds? Wouldn't that require something like a viscosity in empty space?
3
votes
1answer
30 views

Is there any evidence that the Gas Giant planets in our solar system are experiencing orbital migration?

Planetary migration is defined by Lubow and Ida (2010) in their article Planet Migration as the process by which a planet’s orbital radius changes in time. The main agent for causing gas giant ...
3
votes
1answer
47 views

What theories are there in explaining the formation of the Pluto-Charon system?

After reading the question and answer to Effect of Charon on Pluto, a further question is this: how is the Pluto-Charon relationship explained? Specifically, what theories are there in how did the ...
3
votes
1answer
33 views

Long term effect on rocks of high pressure and temperature?

The mean surface temperature of Venus is about 460 C and the pressure is about 92 atmospheres. Assuming this situation (or similar) has prevailed for millions of years what changes (if any) would ...
3
votes
1answer
54 views

Can astronomical radio sources be used as a verifiable randomness beacon?

A randomness beacon is a source of random data that is broadcast to multiple parties. Users listening to the beacon receive the same sequence of random strings and no one can predict the values in ...
3
votes
1answer
85 views

What is the galaxy M87 doing these days?

The massive elliptical galaxy M87 in the Virgo cluster is 53,490,000 light years away. It also contains one of the largest, heaviest supermassive black holes in the known Universe. But it's also my ...
3
votes
1answer
85 views

Sun from SuperNova

I have read that our sun was created from older star(s) which had exploded in a supernova. If all the matter is travelling away from the central point of explosion, how does it coalesce back into a ...

15 30 50 per page