4
votes
2answers
33 views

Where to obtain Tycho Brahe's data?

I would like to obtain Tycho Brahe's data on Mars. What would be an authoritative source? One source I could find is this page (the data is given as an Excel file) but I have no idea can that be ...
4
votes
1answer
107 views

How likely is it that the Sun will destroy our electric society?

Given the studies of the Sun and similar stars and the most impressive understanding of its physics, is there any kind of probability distribution for its dangerous behavior? There are also some ...
4
votes
2answers
144 views

Is there an element of chance/chaos in stellar evolution?

Since stars are an ideal example of macroscopic objects, is their evolution determined by their initial mass and metallicity? Are there any non-trivial random internal processes going on that may ...
4
votes
1answer
59 views

Is CMB Polarization simply the temperature gradient of the CMB?

Firstly, I have to admit that I don't fully comprehend the concept of "CMB Polarization". When I think of "Polarization", I normally think of the optical definition of polarization, as defined by the ...
4
votes
2answers
91 views

Is there anywhere I can find some kind of database on all known stars and their properties (mass, surface temperature, radius, and luminosity)?

I have been looking for some kind of collection of all known stars and their individual respective mass/radius/temperature/and luminosity, can you link me to one if it exists? My goal is to write an ...
4
votes
2answers
63 views

Typical wavelength of solar flare

I read that solar flares are customarily viewed in H-alpha light, as a temporary brightening of a small portion of chromosphere. What all can be interpreted from this? Is it because, energy of the ...
4
votes
1answer
58 views

What will New Horizons be able to say about a magnetic field at Pluto?

Does NASA's New Horizons flyby probe to Pluto have instruments to measure Pluto's (or Charon's) magnetic field, if any? I'm a bit confused by the Wikipedia article which says that New Horizons, ...
4
votes
1answer
94 views

How bright are the outer planets, when at close range?

Seven probes have passed by or orbited outer planets. I wonder how their photos differ from the naked eye view one would have if one were actually there. Saturn is 10 AU from the Sun, which means ...
4
votes
1answer
84 views

Energetics of Titans Tholin haze

So, I've googled and wiki'd on this, but no clue, so I turn my question to the community: Given Titan's nice orange haze that is supposedly composed of Tholins and strangely coincides with its ...
4
votes
1answer
88 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 ...
4
votes
1answer
74 views

Is it conceivable that the presence of chlorophyll (or similar) could be distinguishable from other chemicals on an exoplanet?

If an Earth-like exoplanet had a sufficiently extensive plant biosphere (i.e large forests, aquatic algal mats etc), is it at all conceivable that scientists could spectroscopically detect the ...
4
votes
1answer
32 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. ...
4
votes
2answers
111 views

Assuming a sufficient amount of mass above the density threshold, does the actual concentration of the mass matter in creating a black hole?

I've heard that the actual density of a black hole (within the volume of the event horizon) is pretty low - does that mean that any sufficiently large volume of mass over that density is also a black ...
4
votes
1answer
26 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? ...
4
votes
1answer
35 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 ...
4
votes
1answer
117 views

What is the explanation for rapid inflation just after the big bang?

I often hear about cosmic inflation occurring rapidly after the Big Bang, but have never came across any explanation for it. What supposedly caused this inflationary period in the early universe? ...
4
votes
1answer
26 views

2SB mixer in radio astronomy?

In literature about the instrumentation of radio astronomy, I frequently come across a type of mixer described as "2SB". I'm familiar with single-sideband (SSB) and double-sideband (DSB) mixers, but ...
4
votes
1answer
80 views

What kind of collision of celestial bodies would be visible to the naked eye?

When asteroids crash into the Moon they give of huge amounts of energy resulting in a "bright" flash, as can be seen in this video. At the end of the video its also says that anyone looking at the ...
4
votes
1answer
50 views

Where will I be able to see the Lyrid meteor shower?

So supposedly the Lyrids meteor shower will take place between early morning April 16th to 22nd - correct me if I am wrong. I am aged 15 and am interested in skywatching, I just wondered will it be ...
4
votes
1answer
179 views

Why are most planetary orbits nearly circular

In our solar system, with the exception of Pluto all planets follow a relatively circular orbit around the Sun, at the same inclination. They also all rotate in the same direction, none are ...
4
votes
1answer
62 views

Are many exoplanets synchronously tidally locked like Mercury?

The only tidally locked planet in the Solar system i Mercury. But it is synchronously tidally locked 3:2, because of the relatively high eccentricity of its orbit, so doesn't turn the same side ...
4
votes
1answer
315 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
150 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
96 views

Brightest Radio Source In the Universe

I would have assumed that the brightest radio source in the Universe is a quasar of some kind (perhaps 3C 273) given that the average pulsar has luminosity of $~10^{40} \text{Watts}$ and this is the ...
4
votes
2answers
86 views

Is sundial time entirely dependent on solar azimuth?

I've visited several "how sundials work" sites and can't seem to get a clear answer to this: is "sundial time" just a linear function of solar azimuth? More specifically: When the sun is due ...
4
votes
1answer
1k views

How to measure the altitude and azimuth of a star?

Given that the star is crossing the local meridian line in a certain location, I've tried calculating the altitude of a star by finding the difference between the declination of the star and the ...
4
votes
1answer
36 views

Are we still in the Solar Maximus stage? Will this winter 2013/14 be a good aurora-viewing season?

I remember reading in 2011 that 2013/2014 would be the peak of the current solar maximus, but I want to confirm whether that is still ongoing. Will the upcoming winter season be a good time to see ...
4
votes
1answer
22 views

Astronomical databases for machine learning?

I was reading this question about open problems in astronomy. The bounty-receiving answer says that I have just left the field where some colleagues are trying to develop some software to use ...
4
votes
3answers
161 views

how far away could we detect that earth has life?

My guess is that life bearing planets are too far apart to be detected. I think we can only find the ones within a sphere around our planet that is 100s of light years in diameter but I suspect life ...
4
votes
3answers
203 views

Is there enough hydrogen left after a star dies so another star will have enough to light up?

A star consumes quite a lot of hydrogen in its life, and is pretty much "vacuuming" everything in its vicinity. After it dies (eventually by supernova which will spread all its composition over light ...
4
votes
2answers
188 views

Weight of a celestial body

How do astronomers find out the correct weight of a planet even though there isn't any direct means to weigh them? What technique do they use? Just curious!
4
votes
1answer
59 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 ...
4
votes
1answer
124 views

How many new galaxies enter the observable universe each day/year/decade?

Each day light has more time to reach our eyes from distant galaxies. In one day, light travels 2.59×10^10 km. So our observable universe (assuming my simple math skills apply here and there isn't ...
4
votes
1answer
117 views

Maximum Amplitude of a Lissajous Orbiting Object in a L4 or L5 Position

I stumbled on The Lagrangian points during some wikipedia reading. After looking at the gravity contours, I naturally come to the conclusion that the L4 & L5 should have a wave pattern and then ...
4
votes
1answer
135 views

How did Copernicus get the idea of heliocentric model?

The heliocentric model marked the beginning of modern astronomy. But what were the reasons which led Copernicus to think that the earth orbited the sun. I've read that his model was based on ...
4
votes
1answer
58 views

Density of hydrogen between galaxies

From watching a video on youtube, it states that Dark Matter is 6 times more abundant than known matter. I was wondering if it was possible to have hydrogen clouds between the universes galaxies. The ...
4
votes
2answers
132 views

Galactic Habitable Zone

Do galaxies have habitable zones the same as stars do? Say in a galaxy with a very active nucleus producing a lot of heat and radiation, would there be a point at which no star's planets could harbor ...
4
votes
1answer
82 views

What's the smallest scale at which dark matter has been measured?

What is the smallest scale at which we have detected "dark matter" (more kinetic energy than would be predicted)? If you don't mind indulging a follow-up: Would its detection on smaller scales be ...
4
votes
1answer
663 views

What is the maximum transmission distance of the radio signal in the outer space which could still be understood?

I’ll put this question in a form of a physics problem: Transmitter at a point A sends a signal to a receiver at a point B. What is the longest distance in light years from points A to B for which ...
4
votes
1answer
185 views

Can I see comet ISON from Saudi Arabia?

I live in western Saudi Arabia, I am trying to see the comet ISON, reading here and there tells that I can see it by naked eye somewhere next to the constellation leo, I used an app to tells me where ...
4
votes
2answers
100 views

Likelihood of a stable system with a dwarf planet's orbit inside that of a gas giant

I keep thinking of various planetary system configurations, and would like to know: What are the fundamental references based on Monte Carlo long-term simulation of planetary systems' evolution that ...
4
votes
0answers
31 views

Going from the second moments of an object to its ellipticities and half-light-radius

I am studying ellipticity distributions of galaxies and am having trouble moving from the second central moment matrix (covariance matrix) to properties for an object such as its half-light radius. I ...
4
votes
1answer
152 views

What is the bluest narrow band filter mounted on ground based telescopes?

If we want to check a QSO's lyman alpha narrow band image, could a ground based telescope do that? I mean under the circumstance that its lyman alpha shifts to 3300A.
3
votes
4answers
407 views

Why don't we feel the speed of earth moving

When we move our vehicle, we "feel" the speed of it. However, when stationary, we still are moving,but moving by quiet a speed. We know that earth moves with X ...
3
votes
2answers
109 views

Why do pictures of the Milky Way look like a spiral?

When I see pictures of the Milky Way they show a spiral shape. Why is this?
3
votes
5answers
289 views

Why aren't there galaxy-sized balls of iron out there?

Since we know that stars burn out, collapse, or blow up when too many of their atoms fuse inti iron, then how come, with all the ancient galaxies we've been observing, there isn't one galaxy whose ...
3
votes
4answers
220 views

Is it possible to extend the life of a star?

Is it true that when a star 'runs out' of its fuel, it hasn't really used up all its hydrogen, it still has hydrogen left, but the hydrogen is not at its center where the fusion happens. If something ...
3
votes
2answers
383 views

What is the name of that which exists beyond the Universe?

"The Universe is commonly defined as the totality of existence" but that is more of a philosophical position. Empirically we know (or believe) that it is of finite size some believe it is expanding ...
3
votes
3answers
194 views

What gases are needed to make a star?

What gases do you need to start the creation of a star, and why do you need these gases? What are their functions?
3
votes
3answers
143 views

Is gravitational energy released when a body contracts?

Kelvin stated that gravitational energy released due to contraction was responsible for the energy radiated in the stars. Although the theory was wrong, was the assumption practically right? If it's ...

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