0
votes
0answers
3 views

Eyepiece projection photography

Nothing is showing up in the viewfinder of camera when I try to do eyepiece projection photography.could I have something set up wrong?
0
votes
1answer
4 views

a random distribution of RA&Dec

How to make random positions in Equatorial coordinate system? If I divide Dec between -90 and 90 evenly, the space distribution is not random.
0
votes
0answers
6 views

Why is the CMB not simply travelling parallel to us?

When we look to the distant farthest reaches of the universe we see light that was emitted at the big bang 14 billion years ago. But the universe was tiny back then so that light, which is only ...
0
votes
0answers
21 views

How can black holes be sometimes so gaseous?

One of the most massive Supermassive Black Hole observed is the one at the centre of the galaxy NGC1600 with a mass of 17 billion suns. It would have a density of ∼0.01kg/m^3, or one part in 100,000 ...
0
votes
1answer
19 views

How do astronomers distinguish the spectral lines?

As a black body a star emits a continuous spectrum of light and other radiation. I've learned they are capable of knowing of what elements the stars are made of because of the spectral lines. But how ...
0
votes
1answer
30 views

How would seasons at the equator be if the Earth were tilted 90 degrees?

If Earth's axis of rotation were tilted 90 degrees, what type of seasons would be observed at the equator. My prediction is that there would be no seasons, as the orientation of the equator would be ...
1
vote
2answers
47 views

How close would merging black holes have to be to feel gravitational waves?

Recently LIGO discovered gravitational waves caused by two black holes that were orbiting each other, and then collapsed into one black hole. A few months later, we find out that this actually happens ...
0
votes
1answer
30 views

an exercise from Spherical Astronomy by Smart

I want to solve this exercise from Spherical Astronomy by Smart: Prove that, in latitude 45°, the interval between the moment at which a star's azimuth is 90° east and the moment of setting is ...
1
vote
1answer
24 views

Unable to achieve focus

I feel like this is going to be a duplicate of this question, Astrophotography - Unable to achieve focus with current setup. However, the suggestions to go to a straight adapter doesn't apply in my ...
0
votes
1answer
43 views

Send a rocket against orbit around the sun

I presume it's a bit simplified, but ... What if we launch a rocket, the same speed but opposite direction of the orbit of our planet around the sun. Will that rocket fall into the sun?
0
votes
0answers
27 views

Is it possible to build space elevators? [on hold]

Can we build an elevator so high that it goes out of the earth's atmosphere and can be easily used to launch satellites??
0
votes
1answer
44 views

Distance and orbital period for terrestrial binary planets

This article, http://phys.org/news/2014-12-binary-terrestrial-planets.html, suggests binary planets could orbit each other at a distance of only three planet radii. For two earth-like planets, that is ...
5
votes
1answer
554 views

What is the Galactic Latitude and Galactic Longitude? How is different from the latitude and longitude we use on Earth?

It has to something with the positioning of sun and galactic center of the milky way but I wasn't able to understand how for a given star, its co-ordinates are calculated. Some explanation would be ...
1
vote
2answers
34 views

Having some weird issues with my tracking (Advanced VX)

I need your help! I am having some weird tracking issues with my tripod (Advanced VX). When I setup and calibrated my scope yesterday I took this picture of NGC6888 (90s exposure): As you can see ...
1
vote
2answers
61 views

Black hole darkness a result of gravity or temporal distortion?

Please correct me if I am wrong as I may have made some incorrect assumptions. Okay so we know that at some stage of "nearness to a black hole", light is no longer reflected back at us from the black ...
0
votes
1answer
43 views

Black holes and material interaction

I was wondering about what happens when a black hole forms. I mean, a black hole forms when a star collapses, so when an enormous mass of protons, electrons, neutrons etc collapses together. But when ...
1
vote
1answer
39 views

How to understand orbit definitions

I've been reading about satellite observations (such as this one). The writer uses terms such as these to define the orbit: ...
1
vote
1answer
28 views

What is the name of the cycle whereby the lunar azimuth and altitude recur on a given day?

Like the Metonic cycle, except for position in the sky, not phase. Original question: If I look up at the moon tonight, how long before it is in the same apparent position, and same phase, again? I ...
1
vote
0answers
31 views

a math problem in Spherical astronomy [on hold]

this is an exercise from Spherical astronomy by Smart, which i want to solve: $\frac{d \eta}{d H}= -\cos(\phi) \cos (A) (\sin (z))^{-1}$ when $\phi$ is latitude, $\eta$ is parallax, $H$ is sidereal ...
1
vote
1answer
49 views

Could the Sun's magnetosphere block extraterrestrial contact?

I was reading how certain strong magnetic fields can block or alter radio waves so bearing this in mind would it be possible for the Sun's magnetosphere to block attempts to establish radio contact ...
0
votes
0answers
19 views

What are the requirements to become a planet? [duplicate]

A planet is taught to us (at primary school) as a ball of rock that orbits around the Sun and is similar to our own planet, Earth (in as a ball of rock). But of course, humans have to be more specific ...
0
votes
0answers
12 views

Virial coefficient when computing dynamical mass enclosed by a rotating galactic disk of gas

Suppose I have a large thin disk of rotating gas in a galaxy -- the disk has a maximum inclination-corrected $V_{max}$ and a maximum radial extent of $R_{max}$ corresponding to that $V_{max}$ ...
31
votes
1answer
6k views

How can there be 1,000 stellar ancestors before our Sun?

I've heard from a few sources recently that the Sun is a 1,000th generation star, meaning it had a thousand stars that came before it based on it's heavy element content. I understand that earlier ...
4
votes
1answer
72 views

Would a viewer see Earth from the rim of Shackleton Crater?

I've been researching this but so far have not found an answer. If you were standing on the top of the rim of Shackleton Crater at the lunar south pole, would you be able to see any of Earth? I can't ...
2
votes
2answers
91 views

Could this three moons system be stable?

In my fictional world I have selected all parameters to maximize the Hills Sphere of my planet. The planet has three times Earth's mass and it is located in 2 AU from its star that's 1.4 times more ...
1
vote
2answers
104 views

What would Earth be like without the Moon?

If somehow our moon was destroyed (for example by an asteroid) what would happen to Earth? Would the Earth be affected by the absence of the moon? Would humans be able to live normal lives without ...
1
vote
0answers
21 views

Is there always visible airglow from space? [migrated]

Looking at time lapses taken from the International Space Station, I discovered that earth atmosphere can glow at night, even when it seems that those pictures were taken far away from auroras. ...
0
votes
0answers
79 views

What is Half-life of knowledge in Astronomy? [on hold]

This question is inspired by this answer. About 16 years ago, we knew different numbers of stars in Polaris system than we do now. Even though we have come a long ...
0
votes
0answers
13 views

Where can I find the DR12 SDSS dataset in their website

I have to cross-match the SDSS DR12 dataset with that of GALEX but apparently I cannot find the fits document which has the same field as that in GALEX. I have explored the website but I couldn't find ...
5
votes
2answers
120 views

How many actual stars are Polaris?

I am getting conflicting accounts everywhere. I heard astronomers saying Polaris is a 3-star system. Some say they are binary but are optical-doubled with a 3rd. ...
-1
votes
0answers
45 views

Are a white hole's forces completely opposite of a black hole? [duplicate]

Would not all the forces of a black hole be opposite if the light is escaping from it? For example, rather than it attracting everything to it, would it repel everything?
7
votes
2answers
61 views

How was Earth's “quasi-satellite” 2016 HO3 “first spotted” and it's orbit determined?

Under a question I asked a few days ago Have there been any documented mini-moons since 2006 RH120? @Hobbes mentioned the recent news about 2016 HO3 - a near-Earth asteroid that stays near Earth ...
1
vote
1answer
38 views

How can I convolve a template spectrum with a photometric filter response spectrum?

Suppose I have a template stellar population spectrum (say, from Bruzual & Charlot 2003) which runs from like 1000 Angstroms to 160,000 Angstroms and which has x-axis wavelength units of Angstroms ...
0
votes
0answers
31 views

Question on retrograde motion [duplicate]

I am a beginner Does planets exhibit retrograde motion (eg Mercury and Venus) only because of earth rotation? Or is there any other reason? Please clarify
3
votes
1answer
129 views

What starting circumstances have to be for “grand tack” hypothesis to work, and why they are lacking in other planet systems(as far as we know)?

I recently read a bit about "grand tack" hypothesis. It was extremely interesting and it seems to reasonably well explain many features of our solar system. At the same time it supposedly is ...
3
votes
2answers
77 views

How to find which part of the sky a photo contains?

I was taking some photo stacks yesterday, and I also took a plenty of random ones (pointed not at a specific object) too at 200mm. However, I've ended with a shot but I have no idea where I pointed ...
3
votes
1answer
118 views

Could the word “multiple stars” include binary stars?

We are translating some illustrated book for kids about astronomy, and then have a question as in the title. Referring to Wikipedia etc., It appears that "binary stars" represents the star systems of ...
0
votes
2answers
46 views

Survival on a rogue planet [closed]

Are there any planets not orbiting a celestial body which can support life despite the temperature? Also what is the absolute minimum temperature that life can survive in?
0
votes
0answers
23 views

Negative Spectral Flux Density

I am working on a project and using some satellite images. In some of the images the Spectral Flux Density is negative. What does it indicate?
1
vote
2answers
55 views

Can a rogue planet neither orbit around a star nor a galaxy?

As we know, rogue planets don't orbit around a star, how about galaxy? Can a rouge planet not orbit around a galaxy?
0
votes
1answer
25 views

How do I apply a velocity shift to a wavelength array with uniform logarithmic spacing?

Suppose I have a wavelength array for a spectrum in units of Angstroms. Suppose further that the wavelength has "uniform logarithmic spacing" such that if I just take the difference in Angstroms ...
0
votes
0answers
5 views

How do I reduce planetary photometry to standard viewing geometry using phase angle?

I'm trying to make light curves for Pluto using old data. Most papers give magnitudes "reduced to standard viewing geometry" of r = 39.5 AU, Δ = 38.5 AU, and α = 1 degree, where r is ...
3
votes
0answers
34 views

“Extinct Species” of meteorite - how quantitative is the statistical analysis?

This recent paper in Nature A new type of solar-system material recovered from Ordovician marine limestone is available to read on line, and Figure 3 is already widely publicized. Comparison of ...
0
votes
0answers
24 views

How a model of satellite launching is made? [closed]

What is the necessary knowledge a person should have in order to make a model for satellite launching ?For example,he should have strong background in applied mathematics or in physics etc. Thank you!...
1
vote
3answers
131 views

why was the probability of one in 10 billion per planet considered highly pessimistic by a recent study on aliens? [closed]

A recent article about the existence of extraterrestrial life claimed that "unless the probability for evolving a civilization on a habitable-zone planet is less than one in 10 billion trillion, then ...
3
votes
2answers
109 views

Techniques for locating origin of gravitational waves

The gravity wave detections (GW150914 and GW151226) have both been ambiguous in their exact position, the LIGO papers (GW150914 and GW151226) give no precise information about the location of the ...
2
votes
0answers
70 views

Which astronomical objects do we have images of, taken at ground level? [closed]

I am looking for images of astronomical objects taken at the ground level of the actual object, by something on the actual object, i.e. the Mars Rover. Is this the complete list and accurate?. ...
7
votes
2answers
158 views

Is it possible for a moon to continuously have a side facing its star whilst orbiting a planet?

For example; is there any possibility for the moon to always have a side facing the Sun whilst orbiting Earth? And if so then what would the day cycle be like?

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