0
votes
1answer
33 views

How do I see DSO's in my telescope? [duplicate]

I just bought a new telescope. I tried it out, and I even woke up at 3am when the moon set so there was light pollution. I have an 8 inch dobsonian telescope with a focal length of 1200 mm. For some ...
0
votes
2answers
47 views

How long would it take to reach the edge of the reachable universe?

How long would it take to reach the current edge of the reachable portion of the universe, with the following bounds in mind: We figure out a way build a space ship to provide a constant 1 G ...
2
votes
2answers
41 views

Triple stars with retrograde orbits

Where can I find the observed frequency of triple star systems where the outer star is in a retrograde orbit?
0
votes
1answer
80 views

How do I see more than just points in the sky?

I just bought a new telescope with these specifications: Aperture: 203 mm Focal Length: 1200 mm F/ratio: f/5.9 I usually use a 28 mm eyepiece, giving me about 42.5x magnification, but I also have ...
1
vote
0answers
50 views

Coordinates reduction python

How can I calculate position (alt, az) of star for observer at some station (longitude, latitude) on specific date and time? I need full coordinates reduction with all elements included in calculation ...
0
votes
1answer
29 views

Open source alternative for RegiStar (align, rotate, and combine images into single frame)

I'm looking for a free, open-source and Linux compatible alternative to the RegiStar software. I need it to automatically combine several images into a single frame, where each individual image shows ...
0
votes
1answer
70 views

How to calculate a planet's apparent size when the planet is viewed from a moon in orbit around it?

Specifically in this case, how large would Jupiter be seen in the Io's sky in comparison to the moon in the Earth's sky? How to calculate this? Also, if somebody knows any online software which lets ...
0
votes
1answer
13 views

How do i get focussed images with my T-adaptor and 6mm eyepeice?

I have a Celestron 5se + canon 650d. They are mated with the celestron t-ring and the 93625 t-adaptor. I want to take magnified photos of planets with the camera. But if I add an eyepiece to the ...
1
vote
2answers
141 views

What is the fifth moon-like object I saw around jupiter through my telescope?

Tonight while observing Jupiter I was able to see a five (what looked like) moons. I have observed Jupiter often before and only been able to make out the four galilean moons. It's my understanding ...
2
votes
0answers
19 views

How do people derive ionized gas mass from optical emission lines in a galaxy spectrum?

Suppose you had an optical spectrum of a galaxy, and you unambiguously detected emission lines from cooling ionized gas -- both forbidden lines like [O II] 3727AA and [O III] 4959,5007AA, as well as ...
0
votes
1answer
42 views

What could be a star-like object that shines at daytime for few seconds? What's the probability to see it?

Some years ago I looked up to the blue sky, around 2 PM, and I saw, for 2 or 3 seconds, something like a star fading out. Could it be a Supernova or another phenomena? Is it highly possible?
1
vote
0answers
29 views

What are the conditions for an ionosphere to form?

What are the conditions for an ionosphere to form on a given planet? Factors I could think of are Class and age of the star the planet orbits Distance to said star Density and composition of the ...
1
vote
0answers
29 views

Yuri Milner and Stephen Hawking - Nanobot - Alpha Centauri [migrated]

Does anyone know what exactly is their plan, once they get there? How is that nano-thing going to slow down / take images / send data back to us ? I couldn't find any information on this.
1
vote
1answer
58 views

Mass of Star Collapse

Does a star, when collapsing into a neutron star, or even a black hole, pick up any significant relativistic mass due to its rapid collapse rate?
0
votes
1answer
50 views

In rocky planets,does fast rotation cause flatting or low flatting imply slow rotation?

As far as I know, Venus and Mercury have 0 flatting, but Mars and Earth have detectable flatting, and Venus and Mercury are both rotating slowly. I'm confused as to the relation between rotational ...
3
votes
1answer
116 views

Why is the Sun's brightness and radius increasing, but not its temperature?

On the Sun's article on Wikipedia, there is an image showing how the Sun's brightness, radius and temperature have changed over time: For the past (and next) few billion years, I see the luminosity ...
3
votes
1answer
55 views

Estimating galactic dust extinction for medium band filters

I have a set of medium-band filters and I would like to compute $A_{\lambda}/E(B-V)$ for each filter which are not reported in the literatures. The magnitudes of the objects in the photometry ...
3
votes
1answer
134 views

Conceptual Doubt regarding the calculation of the Solar Constant

The Solar constant is the intensity of the solar radiation in the upper atmosphere. It's value is about $1400$ $Wm^{-2}$. Now we begin by stating that the Power radiated by the sun is about ...
0
votes
1answer
36 views

Radio telescope targeting

How do you target a radio telescope on the precise object you wish to observe? You can point it in the general direction but how do you get the information from the exact point in the sky that you are ...
0
votes
1answer
100 views

Why would astronomers want to eclipse the Sun?

I've heard that some astronomers are building an artifical solar-eclipse ship, that should help us to dim the diffraction of the Sun. Why don't we just wait till night? What is the function of the ...
1
vote
1answer
30 views

Why do linear velocity redshifts correspond to linear pixel shifts when the spectra are binned in constant log wavelength?

In Tonry & Davis (1979), they describe spectroscopic redshift measurement via correlating with templates at known redshift. In Section IIIa, they say "Because the spectra are binned linearly with ...
1
vote
2answers
126 views

How can apparent magnitude be negative?

What is the reason for that scale? Is it because otherwise defining an maximum would be too hard(?). Why do objects that are (apparently) brighter get assigned a smaller number (and down to negative)? ...
7
votes
3answers
533 views

What decides the direction in which the accretion disk spins?

Planets lie on the same plane because of the accretion disk formed during the Protostar stage, as I read in this question. I also read about the collision of particles in the gas cloud causing the ...
1
vote
0answers
27 views

Ground Induced Currents on Mars

Since Mars is only weakly magnetized does Mars not suffer from ground induced currents or are they far worse than on Earth?
1
vote
1answer
28 views

How can ionized emission line flux decrease as a function of increasing metallicity or abundance?

The chemical evolution of galaxies is an important way to learn about their formation and stellar/gaseous constituents. Many galaxies show narrow emission lines at optical wavelengths (3500-9000 ...
-2
votes
1answer
45 views

Finding Mass of Star with only Luminosity

Estimate the mass of the star given this formula: $L/L_\mathrm{sun} = (M/M_\mathrm{sun})^{3.5} $ Given $L= 2.752\times10^{28}\,\mathrm{W}$, how do I find the Mass of the star? Thanks for any help.
0
votes
1answer
55 views

How accurately can you tell the time using a photo of the stars?

If I were to go out on a clear night, in an area with low light pollution, and take a photo of the stars, could an expert analyze the photo and figure out what date the photo is from? We can assume a ...
0
votes
3answers
34 views

Need Simple equation for Rise, Transit, and Set time

I've been looking, unsuccessfully, for hours for a simple set of equations: Input: RA and Dec of an object Observers Lat and Lng Current Time Output: Rise Time Transit Time Set Time (and, ...
0
votes
1answer
33 views

How high does light pollution reach into the sky?

I want to know how high does light pollution typically reach into the sky STRAIGHT UP? Has anyone ever researched this because I wonder if being at 10000ft elevation would reduce the amount of light ...
0
votes
2answers
27 views

Question on Equatorial and Galactic coordinate systems

I'm currently working with proper motions and have needed to convert my galactic longitude and latitude into right ascension and declination (ie from galactic to equatorial coordinates). This is fine ...
0
votes
1answer
42 views

Why do most meteors vanish just before hitting the ground?

Many times we see in the sky that most of the meteor shower trails vanish when they are about to strike the earth several feet above the ground. Why does this happen? They could strike the earth's ...
1
vote
1answer
54 views

Retrograde motion of planets: reason and time?

I am a beginner. I'd like to understand how planets (except Sun and Moon) exhibit retrograde motion. When does the retrograde motion start for a planet (eg Mars) and how long (time limit) planets ...
4
votes
0answers
62 views

Is Io's orbit or rotation affected by its volcanism?

The rotations of comets and asteroids are affected by outgassing volatilities. Io is very volcanicly active. Does it give Io a varying orbit and a slow rotation? Tidal forces should take longer than ...
2
votes
0answers
38 views

Can the expansion of spacetime be directly measured with laser interferometry (like GW can)

LIGO has a mind boggling sensitivity. What would it take to directly measure the expansion of spacetime, along the laser beam? I suppose it could be done at interplanetary scale.
0
votes
1answer
35 views

The relation between the light of full moon and the distance between the sun and the earth

If we want the full moon to be 2 times more bright,how we should change the distance between the sun and the earth? Thanks for your help.
0
votes
1answer
73 views

What makes the Moon and Venus shine?

Is there some substance on Venus or some kind of material, because neither bodies have any source of light.
1
vote
2answers
32 views

VLT interferometry vs E-ELT?

If the VLT (very large telescope) can use interferomerty to act as a 200 meter mirror, then why are they trying to build the 39 meter E-ELT? What advantage does the E-ELT have, if the VLT can act as a ...
0
votes
2answers
56 views

What would be the apparent magnitude of Betelgeuse if it were as close to Earth as Sirius?

How large and bright would Betelgeuse appear if it were as close to Earth as Sirius, before and after it goes supernova?
5
votes
3answers
126 views

If a white dwarf collides with a giant star, could it create a TZO?

Thorne–Żytkow objects (TZOs) form from collisions between neutron stars and main sequence or giant stars. Ultimately, the neutron star becomes the "core" of the giant star. However, could this also ...
0
votes
1answer
56 views

Term for altitude of the sun?

The sun travels in an arc across the sky. Where I live, during the summer the arc rises higher, but in the winter the arc is lower. Once might speak of highest altitude or elevation the sun reaches ...
0
votes
2answers
114 views

Far side of the moon question

Do all / most / any other moons orbiting a planet synchronize their rotation so as to become tidally locked with it, or is the earth a special case?
0
votes
2answers
51 views

How is it possible that the CMB approaches the earth from all directions?

I presume that the photons from the CMB approach the earth from all directions, otherwise we couldn't detect them with a picture where it is present everywhere in the universe with a tiny anisotropy. ...
0
votes
1answer
27 views

Would a Einstein–Rosen bridge change size and/or position in an expanding Universe?

I appreciate that a Einstein–Rosen bridge has never been observed but since there are some valid theories in General Relativity I thought I'd ask this. Would the start and end point of a ...
0
votes
0answers
30 views

How common are Stars that have no orbiting planets? [duplicate]

How common are Stars that have no orbiting planets compared to Stars that do?
8
votes
2answers
1k views

Is the earth bombarded equally in all directions by neutrinos?

Perhaps it is hard to known for sure because neutrinos are very difficult to detect, although they do go through the earth in very large numbers. But are they passing through the earth equally from ...
-1
votes
1answer
75 views

Explanation for the first spinning neutron star detected in the Andromeda galaxy?

A new class of Neutron stars has been found in the Andromeda galaxy (M31), This is the first time a Spinning Neutron star has ever been detected by astronomers in M31. The article states- “pulsars” ...
1
vote
1answer
82 views

If Venus had moon before and it fell back to Venus, why don't I see a unique, very big crater?

Does lack of a very big crater support the idea that Venus never had big moons before? If not, why can't I find a very big crater from the moon impact?
9
votes
1answer
143 views

If “9 th planet” is ejected by Jupiter or Saturn, why does it have a very far perihelion?

If the "9 th planet" is ejected by Jupiter or Saturn, I think the perihelion should be near Jupiter and Saturn, but now the predicted orbit is very far away from Netpune, why would that happen?
-1
votes
1answer
81 views

How do we know that there is no border at the end of “infinite” space? [duplicate]

It has been suggested that space and beyond is infinite, but admittedly the same hypothesis was made by virtue of the fact that it is physically impossible to prove otherwise. How do we know that ...
9
votes
1answer
1k views

Can dark matter be found in the shape of planets, galaxies etc.?

If dark matter has gravity just like normal matter, does that mean it can also form planets, solar systems and so on? Any answer will be appreciated.

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