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22 views

How to calculate the radii of high orbits above the parallels of 45 and 80 degrees? [closed]

I asked this question in the ”Space Exploration” section but I didn't get an answer. I answer the question here: I am interested in calculating orbits above the parallels of 45 and 80 degrees. A ...
3
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0answers
63 views

What is the history of the Milky Way's relationship with Andromeda?

From what I've read, the Milky Way will collide with Andromeda in about 4 - 5 billion years, and a billion or so years after that the two will merge and become a giant elliptical galaxy. What I'm ...
3
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0answers
61 views

Where does Love's number come from in $\delta m = \frac{1}{2}k_2M_2\lbrace\frac{R_1}{r_\star}\rbrace^3$, the formula for the mass of a tidal bulge?

My question refers to page 165 of this paper. Specifically, how does one derive the equation $\delta m = \frac{1}{2}k_2M_2\lbrace\frac{R_1}{r_\star}\rbrace^3$ for the mass of a tidal bulge? A full ...
0
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1answer
48 views

Estimating a star's radius, temperature, and luminosity based on its mass

(See updated figure and description below.) I've been trying to generate ballpark estimates for the radius, temperature and luminosity of stars in the main sequence based solely on their masses (...
43
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3answers
9k views

Why is Mars cold?

The surface temperatures of Mars are about -87C to 5C, which is much colder than that of Earth's. If Mars has 95% carbon dioxide, which is a Greenhouse gas, why is the surface of Mars so cold? ...
0
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1answer
122 views

Strange object crossing the sky

Was stargazing last night and spotted an object traversing the sky from roughly East to West. It had a bright light that was intermittently flashing but with three different intensities. The "third" ...
1
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1answer
100 views

Given that Kepler's Third Law as stated on most websites doesn't include mass, how does it work for planets in other star systems? [duplicate]

Kepler's Third Law as stated on websites I found while searching for "how to convert between a planet's orbital period and semi major axis" is $P^2 = A^3$ where P is the orbital period in years and A ...
2
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0answers
36 views

Find x,y,z velocity component of a star?

I am trying to find the initial x,y,z velocity components of the Epsilon Lyrae stars. How might I go about doing this? The radial velocities are available on Wikipedia, but I am not sure how to use ...
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0answers
31 views

a budgeted telescope around $150

I live in Mississauga (a large city in Ontario, Canada), I am looking for a budgeted telescope around $150. Which one or what type should I go for to explore the night sky planets?
2
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2answers
81 views

Where can I find permissibly licensed database of stars and constellations?

I'm working on a game engine of sorts, and one thing I did for a previous game which was under the GPL was I had a night sky with the constellations visibly connected and I'd like to do that again. I ...
3
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0answers
54 views

Does it make more sense to upgrade our existing telescope or to buy a new one?

We're at a bit of a crossroads here, since we're faced with what appears to be a tough choice. We've got a Celestron 11" SCT tube with a Losmandy G11 equatorial mount, all bought in 1996. The mount ...
4
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1answer
248 views

Split telescope into two eyes

I am looking for an appendage to attach to the end of a telescope which splits the image into two eyes instead of one. Does such an appendage exist?
3
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2answers
104 views

Venus-Saturn conjunction in Sagittarius on Dec 11, 2019 - How often does this happen?

Venus and Saturn will be approximately two finger widths apart in the constellation Sagittarius on December 11, 2019. I was wondering: how often do Venus and Saturn come together in the sky like this? ...
9
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2answers
2k views

Who is Seyfert, and what is “the so-called Seyfert flare”?

The BBC's Milky Way's centre exploded 3.5 million years ago says: A cataclysmic energy flare ripped through our galaxy, the Milky Way, about 3.5 million years ago, a team of astronomers say. ...
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3answers
201 views

Axial wobble or binary star system

Is our solar system affected by a body unobserved as of yet that causes our solar system to curve through space in an orbit? Is this idea outlandish or us there any evidence to support it? Consider ...
3
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1answer
75 views

Orbital speed is (vector) sum of tangential and normal speed?

Orbital speed definition in wiki does not state clearly - it is just tangential speed component or square root of squares of normal and tangential speed (full speed vector). When we say that moon ...
2
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1answer
52 views

Difference between 3D real space and 3D redshift space?

With regards to cosmological simulations (e.g., N-body dark matter only simulations), I've seen people talk about the positions of objects (halos, galaxies) in the simulation in terms of 3D real space ...
6
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3answers
3k views

How to calculate conjunctions of 2 planets

So, the recent conjunction of Jupiter and Venus seems to have spawned lots of excitement over this "rare" event. But what I can't figure out, is exactly how rare it is. And I've seen such conflicting ...
4
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0answers
37 views

Simulate earth, moon, sun constellation with dates

I would like to simulate the three object distance, specifically the distance of the moon to both, sun and earth for further investigation into tide prediction. What would be a good starting point ...
2
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1answer
47 views

How to query a region on the sky when given only ecliptic coordinates?

I am new at using the Python packages astropy/astroquery and what I want to achieve is to use it to find stars that lay on the TESS continuous view zone (CVZ). I ...
1
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1answer
40 views

Loading contour file in ds9

I have an ASCII file (.con) with the coordinates of vertices of different contours. This file is obtained from Matlab. Now after every set of contour ends there needs to be a blank row in the contour ...
-4
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0answers
39 views

Can we consider Indian Astrology as astronomy? [migrated]

Indian Astrology has mentioned about the basics of modern astrology. Apart from Varaha Samhita any other texts available on Indian Astrology/ Jyotish?
8
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1answer
133 views

How do we know so many details about Big Bang, but we do not know if Universe is finite/infinite?

I understand that this question may be too vague, but I am confused about the following: On one hand we know a lot of "details" about Big Bang, like really precise details, evolution of universe, age ...
1
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0answers
40 views

Reason for Orbital Reflector [closed]

We know that last year, space X rocket took orbital reflector with it into the space. But what might be the reason behind launching this weird object into the space? Does it do any work there?
6
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1answer
133 views

A vertical stick's shadow at solar noon should be straight north/south, right?

At true solar noon, the subsolar point should be directly north or south of you, and therefore a vertical stick's shadow should point directly north or south, right? The Wikipedia page for Sun Path ...
7
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2answers
2k views

Does the cosmic microwave background change over time?

Does the cosmic microwave background pattern change over time? I would assume it is getting "cooler" as in more redshifted as time passes, but I am more interested if the pattern on the background, ...
8
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2answers
250 views

Why is ice on Mars not covered in dust?

There's exposed water ice on Mars, like in craters like this At the same time, Mars has dust storm, covering the solar panels of rovers, and occasionally covering the entire planet So why is this ...
2
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3answers
267 views

How to calculate the pixel size and beam size of an image?

I have an image with some sources in it. I need to get the pixel size and beam size of that image. How can I calculate it?
7
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1answer
703 views

What factors influence the Widmanstätten pattern in iron meteorites?

The cores of iron meteorites exhibit beautiful Widmanstätten patterns, as shown below in the Alvord meteorite (photo by Jim H): I understand these patterns form when the molton nickel-iron core of ...
2
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1answer
69 views

How is Earth's gravity modelled?

The Earth does not have a defined geometric shape. Then how do space scientists who want to put a satellite in orbit model the gravitational field of Earth? Do they assume a single object with minute ...
2
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1answer
61 views

What did i see go by saturn?

I was looking at saturn through a basic reflective telescope. I had it focused and could see the rings. To the left a small dim white dot came across my view passing in about 3 seconds from my north ...
5
votes
1answer
166 views

How (the heck) does Astrometry.net work?

What magic is this? This answer to my question Astronomy detective question: what part of the sky are these photos of? What are a few of the stars? nails it, and the output (linked there) contains ...
3
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1answer
85 views

Can expansion of space blueshift galaxies with respect to one another?

Suppose we have two galaxies in an otherwise devoid space, and suppose the galaxies are gravitating. Suddenly, dark energy kicks in, and accelerated expansion of space begins ... (1D force diagram. ...
2
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0answers
35 views

How to calculate the moon phase angle?

I need to calculate the exact moon phase angle for each our of a day. I have my position in lat and long and a unix timestamp. At the end i would like to be able to caluculate the moon brightness with ...
1
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1answer
102 views

How impermeable are the surfaces of the moon?

In the event that we want to dig into the surface of either face of the moon do we know yet if the surfaces of the moon are particularly difficult or particularly easy to dig in?
1
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1answer
60 views

In what ways can force be applied to a black hole

Besides gravity I have never heard of another force pushing or pulling a black hole. Does an object falling into a black hole push the black hole when it crosses the event horizon? What happens to the ...
7
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3answers
863 views

Calculate the shadow on earth of a large orbital disk

How to calculate the shadow on earth of a large orbital disk (low orbit)?
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0answers
56 views

Are these stars in MASCOT image of Ryugu?

Are these stars in this MASCOT image of Ryugu? Larger image: https://www.sciencealert.com/images/2019-08/processed/RocksOfRyuguStranglyFamiliar_1024.jpg They seem too bright to be stars (if the ...
1
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0answers
14 views

Open dataset from antenna array

I am looking for a raw radio-astronomic antenna array dataset of relatively modest size (on the order a few MB, or even less), to evaluate a data processing algorithm. The dataset ideally should be ...
4
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1answer
84 views

Astronomy detective question: what part of the sky are these photos of? What are a few of the stars?

The 9to5Google article Exclusive: Official Pixel 4 camera samples show astrophotography, selfies, more [Gallery] shows some surprisingly nice (at least to me) photos of the Milky Way. I've asked ...
1
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1answer
53 views

Could someone please explain to me how I can extract velocity component values from Stellarium, for a given planet?

For a project that I am currently working on, I would like to know how one could extract velocity component values ($v_x$, $v_y$ and $v_z$) for a planet from the Stellarium software. The current ...
1
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0answers
37 views

How do large telescopes, especially plans for the LSST, avoid saturation artifacts from the brightest stars and planets?

This interesting answer to What is the LSST's plan to address frequent satellite trails in data? quotes: From the LSST webpage: The first group of Starlink satellites are sufficiently ...
4
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1answer
69 views

What is the LSST's plan to address frequent satellite trails in data?

In the 2011 Sixty Symbols video Spy Satellites (from Deep Sky Videos) after about 01:40 amateur astrophotographer Nik Szymanek says: One thing I find when I’m ...
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5answers
11k views

Gravitation - Pulling or Pushing force?

According to Newton, gravity is the pulling - or in fact the attracting - force of any heavenly body towards any object to its center. But, to the contrary, Einstein once said that the four dimensions ...
14
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6answers
4k views

What does forward modeling mean?

In my research on exoplanets, I have heard many people talk "forward modeling of exoplanet atmospheres". I don't know what the "forward" means in "forward modeling" and how it compares with "reverse ...
1
vote
1answer
25 views

How do I calculate B-V to make a Hertzsprung Russell diagram?

I am reading my textbooks and a few "Astro101" websites, but I cannot find a final answer to this: In the $B-V$ colour index that is plotted in an H-R diagram, are $B$ and $V$ the (observed) apparent ...
2
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1answer
98 views

Universe expansion

I'm reading the book "The theory of everything". In the second chapter it says the Universe is expanding, and we know this because the measurements made using the doppler efect to other galaxies gives ...
3
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0answers
74 views

Can someone calculate the age of the KOI-4878 star?

The star’s low metallicity and fairly high space velocity suggest that KOI-4878 is older than the Sun. But I don't know how to calculate an estimation for the age. KOI-4878 data on Simbad
5
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1answer
107 views

Why is a giant planet around a tiny star unusual when binary stars are normal?

Inspired by this BBC article and the corresponding journal article about the M dwarf star GJ 3512. The Jupiter-like world is unusually large compared with its host star, contradicting a widely held ...
7
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1answer
176 views

First observation that the Sun and Jupiter (and friends) move around a common barycenter?

Answers to the question How did Kepler determine the orbital period of Mars? describing careful observations centuries ago got me thinking. What was the first analysis of observations that directly ...

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