2
votes
2answers
40 views

What is meant by Electronic Beam Steering and how is it achieved?

I recently came across an article about the Murchison Wide Field Array which said directivity is achieved by Electronic Beam Steering and not by Mechanical methods. It would be helpful if someone can ...
2
votes
2answers
70 views

How do scientists know if an Earth-like planet is really Earth-like?

I'm not sure how scientists determine that a planet is really an Earth-like planet. How do they do it?
2
votes
1answer
76 views

why are galaxies different in color?

whether its in movies,television,real-life or some planetarium different galaxies are shown in different color. For ex:- Milky way is always seen in Blue where as Andromeda gives out a bit reddish ...
2
votes
1answer
207 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 ...
2
votes
1answer
72 views

Why doesn't the earth's surface collapse onto itself? [closed]

From what I know the sun (or any other star) nuclear fission keeps it from collapsing under its own gravity until the fuel runs out, if that's so why doesn't the earth surface like the tectonic plates ...
2
votes
1answer
68 views

What would happen if we put a small part of White Dwarf or Neutron Star on Earth?

I would know what would happen if we put a small part (let me assume 1 cm$^3$) of White Dwarf or Neutron Star on ...
2
votes
1answer
68 views

What does black hole evaporation correspond to in the accelerating universe / black hole analogy?

In the same way, as a black hole emits Hawking radiation corresponding to its temperature $$ T = \frac{\hbar}{r_{BH}} $$ the accelerating universe can be described as all of the stuff falling ...
2
votes
2answers
52 views

Is it possible to calculate the time of day given latitude, longitude and solar elevation angles (zenith, azimuth, elevation)?

I am trying to determine the time of day of some images I have. I know the lat/lon, the day and year of image. I also know the 3 solar angles (zenith, azimuth, and elevation). Is there MATLAB or ...
2
votes
1answer
80 views

Could black holes be creators of dark matter?

At the tremendous forces of gravity inside a black hole, can "matter" be transformed into a more degenerate form; "dark matter" (if that truly what dark matter is)? I know the inside of a black hole ...
2
votes
1answer
93 views

In what form was the space at singularity?

It is somewhat imaginable for all the matter or energy to be condensed in sub-atomic size. But what about space? The space is neither 'matter' nor 'Energy'. If there were no space at singularity ...
2
votes
1answer
50 views

What is needed to break through the surface of Europa? [closed]

How big does a satelite we send have to be to be able to chrush through the ice layer and dive into the ocean on Europa? If a mission should head there, is this a better way of examining the ocean ...
2
votes
1answer
95 views

Star names and the HYG Database

Related to Convert coordinates between RA/dec and WGS 84 (SRID=4326). WARNING: I'm a noob in astronomy. After import all stars from HYG Database (http://www.astronexus.com/node/34) I noticed some ...
2
votes
1answer
20 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?
2
votes
1answer
74 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 ...
2
votes
1answer
84 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
2
votes
1answer
54 views

Calculate apsides without knowing eccentricity

How would one go about determining the apsides of an orbit, knowing only the current distance between the 2 bodies, the orbital velocity, and the period? Every formula I've seen requires eccentricity, ...
2
votes
1answer
29 views

iteration to cover the whole sky with right ascension, declination, angle

I am sure I get parts of the terminology wrong but if anyone can shed some light in the following: I understand that for a given right ascension (RA) and declination (DEC), one has defined a ray ...
2
votes
1answer
45 views

Without using absolute magnitudes or isochrones, how might we tell a star's age and evolutionary status?

Usual methods of estimating stellar ages involve isochrone approximations. It can also help to estimate a star's radius by correlating its absolute magnitude with effective temperature and apparent ...
2
votes
1answer
43 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 ...
2
votes
1answer
28 views

Any cheap (<100 euro) tools for observing the lines in solar spectrum?

I am now reading the book ''The story of Helium and the Birth of Astrophysics''. I really want to observe the lines (dark or bright) in the solar spectrum. Any easily available tools for an amateur? ...
2
votes
1answer
38 views

What record do we have of the length of supernovas?

recently I heard an astronomer on the radio claim that the supernova we have observed in our own galaxy lasted about 6 months, while in distant galaxies they last about 7-8 months, due to relativity ...
2
votes
1answer
74 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 ...
2
votes
1answer
50 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 ...
2
votes
1answer
56 views

Taking Advantage of Time Dilation

According to Einstein's theory of Special Relativity, one's speed in relation to a relatively stationary object would 'slow down' time on the moving object. With this in mind, would it be possible to ...
2
votes
1answer
40 views

Broadband spectrum of Sun

Broadband spectrum is one which is inclusive of all the observed wavelength ranges. In the case of the BB spectra of our Sun, there is a sharp (non-differentiable) kink in the curve in the UV-range ...
2
votes
1answer
38 views

Is the local group bound to the Virgo cluster?

The virgo cluster is currently red-shifted by 0.003 according to Wikipedia; this indicates that the cluster is expanding. Will the cluster's enormous gravity eventually "win" and pull the milky ...
2
votes
2answers
82 views

Conundrum involving distance to object, universal expansion, age of universe, etc

I was recently reading about a galaxy or quasar (not sure which, so lets just say quasar) where the estimated distance to this thing was some very significant fraction of the age of the universe. ...
2
votes
1answer
37 views

Why do Jovian moons fade when transiting Jupiter's shadow?

When reading an article on using Jovian moons to calculate longitude, I came across this passage: Periodically, Jupiter eclipses each of the four large moons as they pass into the planet's mammoth ...
2
votes
1answer
57 views

Black dwarf binary systems

I know black dwarf stars do not exist yet, and that they are what white dwarfs end up after a long time. The question is really simple: would it be possible to have a binary system in which one of the ...
2
votes
1answer
134 views

How do I calculate the velocity dispersion of a galaxy given an integral field spectrograph?

I couldn't find on the web how to get the velocity dispersion and velocity maps of galaxies from the 3D data cube that I get from the integral field spectrograph.
2
votes
2answers
25 views

Locate asteroid in asteroid belt

I was interested in tracking the orbit of 1986 DA. I couldn't find any resource when I looked. Just for fun, so any help appreciated.
2
votes
1answer
140 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 ...
2
votes
1answer
46 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 ...
2
votes
1answer
57 views

What are the masses of the two stars (given the information provided)?

If anyone would at least be willing to point me in the direction of finding the answer, or help me solve it I'd appreciate it. I don't know how to go about this, and need to know how to solve this on ...
2
votes
2answers
59 views

Can looking at the sun through solar viewing eclipse shades everyday harm your eyes?

I have a pair of Solar Viewing Eclipse Shades that say "Safe for Direct Solar Viewing" and would like to know if my eyes would be harmed if I looked at the sun everyday for about a minute wearing ...
2
votes
1answer
105 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 ...
2
votes
1answer
266 views

Is C/2012 S1 (aka ISON) the fastest comet on record to-date?

This source may be nebulous (no pun intended!) for some. It writes to say Starting at around 95,000mph at the start of this month, Comet ISON will eventually reach an astonishing 845,000mph on ...
2
votes
0answers
86 views

is there any theory or observational evidence that our universe is electrically neutral or not?

It seems our universe is neutral in large scale. There is CP violationwiki problem about matter and dark matter. Similarly is there any theory about whether our universe is electrically neutral? ...
2
votes
1answer
42 views

Hour angle sunrise calculation problem

I am trying to program a sunrise/sunset calculator using this formula tutorial. If you follow the steps, eventually you get to this formula for "H" (the "hour angle"): $H = \arccos( [\sin(-0.83) - ...
2
votes
2answers
43 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 ...
2
votes
0answers
50 views

what is the farthest object we've been able to bounce signals off of to date?

I know people bounced lasers off of Venus and Mercury in 1960s in order to test the Shapiro delay. Since then, we've developed higher-power lasers and radio transmitters (Bolshakovo transmitter). ...
2
votes
0answers
76 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 ...
2
votes
1answer
46 views

Calculate telescope orientation based on RA, DEC and Lat/Long

I'm parsing FITS files for a project based on data from a telescope. These files include 'DEC', 'RA' and lat long values. I understand roughly the concept of celestial coordinates and I assume that ...
2
votes
1answer
49 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 ...
2
votes
3answers
58 views

Are there standard algorithms and procedures for creating unique sky maps based on latitude/longitude/date/time?

I am trying to build an astronomy app that will use the user's latitude and longitude, along with the current date and time, to create a 3D view of the celestial sphere as seen based on that data. ...
2
votes
1answer
68 views

“How the Universe Works”: is it scientifically accurate? [closed]

The documentary/mini-series How the Universe Works is based on scientific evidence and according to what is known nowadays, or sheer bunk? Throughout the series, are there any particular topics which ...
2
votes
0answers
38 views

Exoplanet naming conventions

I'm looking for any exoplanet nomenclature, official, semi-official, proposed, or just a good idea, beyond what can already be found on Wikipedia at ...
2
votes
0answers
39 views

Why can primordial tensor perturbations of the CMB be ascribed to gravitational waves?

Why can primordial tensor perturbations of the CMB be ascribed to gravitational waves? Is this attribution unique, or are there other michanisms that could lead to the ecitation of tensor modes? In ...
2
votes
0answers
24 views

need data-point: actual counts per second with APD (avalanche photodiode) detector

I'm designing a sensor system to perform specialized [astronomy and space-sciences] experiments, and need a "reality check" to support or adjust my theoretical calculations. What I need is the ...
2
votes
1answer
72 views

Radioactive decay is the main source of the earth's interior heat: fact or theory? [closed]

It's believed the main reason that the interior of the Earth hasn't cooled down in 4 billion years is because of the ongoing decay of radioactive elements that keeps adding more heat than is lost to ...

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