2
votes
3answers
383 views

Why did the moon abruptly change positions in the sky?

Three or four weeks ago I was outside showing my neighbors how cool the moon was through a 'backyard' telescope in broad daylight (~8PM PDT). It was 3/4 of the way across the sky (setting behind the ...
2
votes
0answers
34 views

Given a date obtain latitude and longitude where is the sun zenith

Searching is easy to find terminator line (frontier between day and night) or the position of the sun in the sky given a position on the earth and a time; but I can't find how to obtain where is the ...
8
votes
2answers
232 views

If the Wow! signal was not directed at us, then where?

We probably all know the Wow!-Signal, happened on August 15, 1977. Assume that it wasn't meant for us. What was it pointing at then? The signal at that time came from RA= 19h25m31s ± 10s or 19h28m22s ...
2
votes
3answers
108 views

How is the universe bordered?

This answer says that some models describes the universe as finite. How do those models describe the universe's border? Does the border (theoretically) exist? Is it a solid border? Do they predict ...
1
vote
1answer
114 views

Can General Relativity indicate phase-dependent variations in planetary orbital acceleration?

In a previous question about differences in Newtonian and GTR gravitional force for the case of star-planet gravitational interactions an approximate relationship was noted between the expressions for ...
3
votes
1answer
38 views

Number density of stars on the Galactic plane

The number density of stars (e.g. the number of stars per cubic parsec) is given by $$N(z) = N(0) e^{-|z|/h}$$ where $z$ is the height above the Galactic plane, $h$ is the scale height for a specific ...
4
votes
2answers
92 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 ...
2
votes
0answers
34 views

Instrumental magnitude to “real” magnitude - Photometry with not enough data?

I have a lot of data taken in R, B, V, Luminance and Halpha-bands which I want to analyse photometrically (one target in the frame). The frames are already reduced (with flats, darks etc.) and have a ...
5
votes
2answers
789 views

Does the Moon's magnetic field affect Earth's magnetic field?

I wanted to ask a question; it's simple but I cannot find any possible and perfect solution. Earth has poles, North and South. By which we can get directions using a compass or a needle compass, but ...
2
votes
0answers
37 views

How many observations does it take to determine the orbit of a TNO

Several observations of a distant solar object must be taken before determining its orbit, but in the case of objects discovered beyond Neptune's orbit, just how many are required over what period of ...
1
vote
0answers
27 views

Super massive black hole mass estimation in literature

What is the most accurate method for SMBH mass estimation? In the literature I could find 5 methods : (1) Marconi & Hunt 2003, (2) Hu 2008, (3) Gultekin et al. 2009, (4) Graham 2007, (5) McLure ...
8
votes
3answers
365 views

Why can you see the space station on some days but not on others?

In my area, from December 17th - 26th, you can see the space station every day, twice But from December 27th - January 6th, you can only see it twice My question is, why does it appear for ...
7
votes
3answers
163 views

Is it possible to break apart a neutron star?

I was inspired by this question on Physics, as well as this question right here on Astronomy. Neutron stars are tightly bound together as neutron degenerate matter. They're very massive and have a ...
4
votes
1answer
113 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 ...
6
votes
3answers
171 views

Which stars did the Sun form with?

The Sun formed 4.5 billion years ago, in a molecular cloud. I assume that there were other stars in the vicinity (as is common in molecular clouds). Which stars are they? Where are they now? Are they ...
4
votes
1answer
79 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
159 views

At what density does helium burning start in a star?

I have seen several references that say that helium burning begins in a star once the core temperature reaches $10^8$K (such as here) but nowhere that says what density that corresponds to. Does ...
6
votes
1answer
77 views

Climate modeling of exoplanets

These notes from an exoplanet talk discuss modeling the climate of exoplanets. How would we do that with our current technology? Would data be primarily gathered by spectrum analysis?
1
vote
0answers
18 views

VSOP for exosatellites? (Io, Titan, Ariel, etc)

VSOP87 (and the subsequent VSOP2000 and VSOP2013) provide reasonably accurate planetary positions while still maintaining a small file size compared to the Chebyshev polynomial files. VSOP ...
3
votes
1answer
110 views

Classification of a Comet

Google's definition of a comet is: a celestial object consisting of a nucleus of ice and dust and, when near the sun, a ‘tail’ of gas and dust particles pointing away from the sun. This ...
6
votes
1answer
99 views

Explanation for the mathematics behind Venus' retrograde motion

I've always been interested by the pattern within Venus' orbit around the sun. I found this image and formula of its retrograde motion in the upper right hand corner which confused me. What does it ...
11
votes
2answers
2k views

What is the distance that the Moon travels during one orbit around the Earth?

Also, does it always take the same amount of time, or does it fractionally differ on each revolution?
16
votes
4answers
4k views

If Jupiter is a gas-giant then why don't its features change?

A naive question. When we look at Jupiter, we see that its features didn't change largely over many years, for instance, the red-spot. If it is composed of gases and liquids, then why aren't the ...
2
votes
1answer
76 views

Orbiting supermassive black hole or galactic center of mass?

One of the ways they measure the (supposed?) supermassive black hole at the galactic center of the milky way is to measure those tens of stars right at the galactic center that are orbiting what ...
0
votes
2answers
152 views

Why did the big bang not just produce a big black hole?

Questions I've often wondered about: 1) If all the matter and energy were concentrated at a single point at the big bang, why wasn't that a black hole, or why didn't it form one? 2) If the reason #1 ...
3
votes
1answer
81 views

What would happen if a Black Hole and White Hole Collided?

Given our understanding of both black holes and white holes, what would be the outcome if they were both to suddenly collide? Black Holes: A black hole is a region of spacetime from which gravity ...
18
votes
2answers
317 views

How dense are Saturn's rings?

I assume that the A ring is the densest, but I might be wrong. Nevertheless, I failed to find any explicit information over the net about the minimum and maximum of densities for the different rings. ...
1
vote
0answers
56 views

How do we know the big bang expanded space and not the other way around?

Whenever we hear an explanation about the big bang, it is always phrased in such a way that it was an explosion which used some kind of pressure to expanded the universe out. I wonder, however, would ...
14
votes
5answers
389 views

What is in the center of the universe?

If the universe has formed & originated by a Big Bang Explosion, then there must be empty space left in the center of the explosion site, as all the matter is travelling at tremendous speeds away ...
8
votes
1answer
63 views

How far apart is the dust in the Sombrero Galaxy's dust lane?

In his answer to this question, TildalWave made this remark: I think that first, we have to properly appreciate the size of the Sombrero Galaxy. It is roughly 50,000 light years (15 kilo parsecs) ...
5
votes
1answer
95 views

Composition of planets' core

It is often possible to find a list of the materials that compose the cores and the mantle of plantes (often they are iron and/or nickel). How can these materials be determined in our Solar system? ...
5
votes
3answers
201 views

I'd like to become an astronomer. What experience do I need? [closed]

I think I'd like to become an astronomer. What degrees and training/experience do I need to become one? I've heard I should take science and mathematics, but I don't know which specific courses I ...
1
vote
0answers
28 views

Synthesising types of galaxies using various stellar spectra

I have asked this on Physics Stack Exchange but Astronomy is probably more appropriate. I have been given the task of synthesising an elliptical galaxy, a starburst galaxy and a spiral galaxy ...
1
vote
2answers
67 views

Is gravity a source of infinite energy at a cosmological scale

As I understand it, gravity cannot be attenuated by any medium (in the way that EM radiation can be, for instance). Does this, then, not make it a source (theoretically, I am not talking of ...
4
votes
2answers
88 views

Can a gas giant have an other gas planet as satellite?

Is it possible for a gas giant (A very big one) to have an other smaller gas planet as satellite?
1
vote
1answer
55 views

What are the color progression of a typical sunrise?

"Dawn simulators" are used to simulate a natural sunrise, or at least the physiological effects of one. What temporal sequence of color values (e.g., hue, saturation, brightness, and timing) ...
2
votes
2answers
80 views

Is the white hole a myth or not?

I've been doing some research on white holes, and there has not been enough information to provide the answer. Some websites are saying that they might exist, but it is not yet proven. So, is it true ...
-2
votes
2answers
90 views

why quantum gravity doesnot exist?

I am not an astrophysicist and not its student.All my knowledge about astronomy comes from you tube videos and discovery channel.From them i knew that to solve the mysteries of black hole both ...
-2
votes
1answer
58 views
3
votes
1answer
65 views

Why does Jupiter break comets apart?

I understand that there are magnificent tidal forces that come with getting too close to Jupiter, but what is causing comets like Shoemaker-Levy to get torn apart? I wouldn't expect that the ...
13
votes
3answers
126 views

When will we be able to detect Earth-sized exoplanets?

I have heard that the only planets able to be seen outside the Solar system are Jovian-sized planets with the occasional detection of planets three times the Earth's size. But, as far as I know, we ...
0
votes
4answers
101 views

Is the Drake Equation an accurate way of finding the probability of life on planets?

I was interested in finding out if there was life on any planets or moons. I saw ReNiSh A R's question, and I saw the answer about there being life on Europa, but it didn't accurately answer what I ...
12
votes
5answers
7k views

What will happen to life on Earth when Andromeda and Milky Way galaxies collide?

It is said that, Andromeda and Milky way galaxies are coming close to each other with the speed of approx $400000 \ km/hours$. They will be together in the next $4 \ billion years$. What will ...
3
votes
1answer
124 views

Could we fly/drive through Jupiter?

If Jupiter is made of gas, could we fly or drive through it or would its center be too dense?
6
votes
1answer
82 views

Why does this graph for sunlight intensity on land has a steeper slope during sunrise as compared to sunset?

I got this image while checking weather data for a city in North India using Mathematica's Wolfram Alpha query I noticed one feature in the graph which i could not explain . Why does the encircled ...
0
votes
1answer
54 views

Companion Sun the cause of comet impacts with Earth

On television, I heard a scientist who believes that our Sun has a companion (brown dwarf) Sun, that is responsible for comets destroying life here on Earth every 26 million years. He proposed the ...
1
vote
1answer
59 views

How would Special relativity explain past-present-future if thinking about 13-billion-light-years distanced objects

Halo. I'm interested in how would Special relativity comment on this: Suppose there are 2 objects, A and B. They are 13 billion light years away from each other. When the light from the B object ...
-3
votes
1answer
110 views

Black Holes, how do they form?

Do black holes form by when the massive star dies and all the gravity falls in on itself, or something else. Please let me know, I'm really desperate!!
1
vote
3answers
97 views

What happens to photons that don't interact with something?

Say a photon left one of the first stars ever created in our universe. This photon has been traveling for 13+billion years through the vastness of space without ever hitting anything. Sure, it's ...
5
votes
1answer
133 views

How can we tell if the asteroid 2013 TV135 will hit Earth in 2032?

Some astronomers in Ukraine have estimated that there is a small likelihood (1 in 63,000) that the asteroid 2013 TV135 will strike Earth in 2032. (source) Don Yeoman of NASA JPL says: with more ...

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