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23 views

If all stars rotate, why was there a theory developed, that requires non-rotating stars?

According to Penrose's research, a non-rotating star, would end up after gravitational collapse as a perfectly spherical black hole. However, every star in the universe has some kind of angular ...
0
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1answer
30 views

Is tracking of unknown aerial vehicles beyond Earth atmosphere possible or even have been done already?

Afaik there are lots of deep space and Earth surroundings radar based asteroids observations. Now I've come across the USS Nimitz accident in 2004: there has been officially confirmed, now ...
3
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1answer
16 views

Clearing the Neighbourhood: Definition of 'Orbital Region'?

I am trying to determine how wide a 'neighbourhood' a planet is expected to clear. However, the Wikipedia article on the matter provides no clarity, simply stating that a planet is expected to clear ...
3
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0answers
18 views

What are realistic and unrealistic values for the high energy gamma ray spectral indices of pulsar wind nebulae?

This summer, I was working on a project fitting very high energy gamma ray spectra of the Crab Nebula, a pulsar wind nebula. At energies about $\sim$1 TeV, a simple power law suffices, i.e. $\phi(E)\...
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0answers
44 views

What made him think so? [on hold]

I've been looking into Einstein's theories and was struck with this question. It's contradicting the physics what I've been taught at school. How can mass change with increase in speed and what made ...
5
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1answer
66 views

Why does Titan have an atmosphere while similar moons such as the Galilean moons don't?

The Galilean moons of Jupiter are similar in size to Titan and are also protected by their parent planet's magnetic field. How come only Titan is able to maintain an atmosphere?
2
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1answer
46 views

Why would a tidally-locked rocky planet have a first-order spherical harmonic surface temperature distribution?

The new Letter to Nature Absence of a thick atmosphere on the terrestrial exoplanet LHS 3844b (also ArXiv) analyzes the thermal infrared light curve from the system (about 4.5 to 5.5 um). The planet ...
1
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0answers
31 views

SPICE Alt Az example

Original question below, but my question is now about how can I supply lat/lon coordinates for other locations other than the one in the example below? It is possible to use NASA's SPICE toolkit to ...
2
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1answer
72 views

More recent data and simulations of “Milkomeda”, the collision of the Milky Way and Andromeda galaxies?

The Space.com headline Hubble Telescope Spots Two Galaxies in a Doomed (but Dazzling) Dance; The galaxies will ultimately crash into each other was probably overstated as seems to be policy in some ...
18
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3answers
4k views

How do you call it when two celestial bodies come as close to each other as they will in their current orbits?

On Earth, we say Mars is in opposition when it is 180º from the Sun, which also marks the times when Mars and Earth come closest to each other. Is there a specific name for such proximity events? For ...
2
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0answers
78 views

What is the meaning of ellipticity of a galaxy being more than 1?

I was recently doing a project on calculating ellipticities of galaxies using SDSS data. I downloaded the stokes parameter values (q and u) from data $e = 1 - \frac{b}{a} = 1 - \frac{1 - \sqrt{Q^2 + ...
4
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2answers
458 views

How does the illumination of the sky from the sun compare to that of the moon?

I have trouble describing the questions but this is the best I can do. The sun lights up the sky, until it's about 18 degrees below the horizon. The moon also lights up the sky, and i'm wondering, how ...
1
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2answers
68 views

Could anyone recommend a good book about the basics of astrophysics? [on hold]

I am sorry if a similar question has been asked before. I look at other questions but was not entirely satisfied. So, I am a Psychology student who would like to know more about the basics of ...
3
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0answers
74 views

Assuming no light pollution, was “2C. 1406” ever visible to the naked eye?

Joseph Needham, in his Science and Civilisation in China Vol. III, claimed that there was an ancient record of a nova about three thousand years ago. As a result of private correspondences with a "Dr ...
1
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0answers
67 views

Why didn't the parachutes on the Apollo 14 Command Module bump into each other? [on hold]

It seems like they would need some mechanism to keep them apart, but in this photograph I don't see anything telling, unless it's those small pilot chutes that are keeping them apart?
0
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1answer
89 views

Questions about Planck’s law

Two questions: I read online that all objects emit the majority of their thermal radiation in the radio, and that this emission increases with temperature. Does this mean that all glowing bodies emit ...
0
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1answer
70 views

Why is the Sun's Luminosity not equal to the Zero Point Luminosity?

I was doing some research and found that the zero-point luminosity was $L_\odot = 3.75\times 10^{28} $, while the sun's reported luminosity was $L_{Sun} = 3.828\times 10^{26}$, according to Wikipedia. ...
1
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0answers
34 views

PSF magnification

I have a circular telescope pupil, a magnifying optic, and a detector. I am trying to calculate the point spread function as a function of wavelength. I am running into the issue that Python's 2D FFT ...
3
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1answer
85 views

Why is our Sun hotter than UY Scuti?

As Wikipedia says the surface temperature of UY Scuti is 3,365 K and the sun is 5,778 K Why is the Sun hotter than a supergiant star like UY Scuti?
3
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2answers
116 views

Why is Saturn invisible in this radar image of its rings?

The image below is from Radar imaging of Saturn’s rings Nicholson, P. D. et al., Icarus 177 (2005) 32–62, doi:10.1016/j.icarus.2005.03.023 and discussed further in this answer to How did Arecibo ...
1
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0answers
30 views

Apparent Magnitude / Apparent Brightness relationship help

I'm a high-school student that is currently working on a project that describes, using mathematical notation and explanation, how scientists can find the values of each of the properties of stars, ...
2
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2answers
73 views

Can dark energy or dark matter affect black holes

I was wondering if black holes are the greatest force of gravity how does other highly spoken about concepts such as dark energy or dark matter compare. Can a black hole absorb dark energy or dark ...
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1answer
49 views

Control the behavior of a Black Hole

Is it possible to manipulate the size of a black hole or how a black hole behaves if scientists were able to synthesize hawking radiation on demand. That is, if I could find a way to imitate hawking ...
2
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1answer
55 views

The dominance of Gravity vs Strength and its dependency on crater size

So I am trying to write a research paper (about 3700 words) for high school about the topic in the title or something similar. I have found the following information which I am struggling to ...
12
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2answers
4k views

How does the Moon's gravity affect Earth's oceans despite Earth's stronger gravitational pull?

Given that Earth has a much stronger gravitational pull than the Moon, how does the Moon have any influence on Earth's oceans?
4
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1answer
74 views

Local Bubble in space

Is the Local Bubble alone in space or is there another bubble similar to the Local Bubble in space, i.e., do we live in a special place or is this a more general phenomenon?
4
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1answer
82 views

Are there any simulations of the Grand tack?

The BBC program with Brian Cox "The Planets" involved some description of the Grand Tack hypothesis to explain the current state of the solar system. This theory has Jupiter wandering through the ...
2
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2answers
75 views

How does a Super-Massive Black Hole 'flare'?

This week we have read of evidence of the Super Massive Black Hole in the centre of the Galaxy 'flaring'. My understanding is that light cannot escape from a black hole. My question is: How does a ...
5
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2answers
247 views

“Table of Astronomy's” depiction of the solar system models

This is going to be a follow up question to my question about the "Table of Astronomy" from yesterday, What is this “Table of astronomy” about?. I wanted to take a close look at the three depiction ...
3
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0answers
38 views

Textbook advice [closed]

I'm looking for resources/texts to learn more about stars and things. I stopped studying physics when I was 15, so I'm pretty uninformed. However, I do have a pretty good maths background (UG courses ...
10
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2answers
2k views

How did Arecibo detect methane lakes on Titan, and image Saturn's rings?

This answer to Farthest distance to a solar system object that's been measured by radar? mentions that Saturn's rings, and the Uncover Travel post Arecibo Observatory, Puerto Rico – The World’s ...
3
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2answers
107 views

Can an Earth-like planet survive if our Sun went Supernova?

First, I would like to point out, yes, our sun does not have enough mass to be a candidate for Supernova, this is a scenario were our sun is though, and after the various life cycle stages of the sun ...
54
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3answers
13k views

What is the hottest thing in the universe?

Straight from my 7 year old to you, exactly what it says on the cover: What is the hottest thing in the universe? To make it Stack Exchange-friendly, I'll add the following caveats: it should be ...
2
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1answer
59 views

How did they estimate the mass of Sgr A*'s companion G2 without knowing what it was?

Gizmodo.com's Astronomers Spot Unprecedented Flashes From Our Galaxy's Black Hole mentions Sgr A*'s companion gas cloud G2. That Wikipedia article says: First noticed as something unusual in ...
1
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1answer
59 views

Origins and most frequently used; perinigricon vs peribothron?

Gizmodo.com's Astronomers Spot Unprecedented Flashes From Our Galaxy's Black Hole mentions Sgr A*'s companion gas cloud G2 and that Wikipedia article uses the term perinigricon, but that mentions ...
3
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1answer
86 views

Have more recent LIGO/VIRGO gravitational wave measurements narrowed down the speed of gravity further?

This answer to How precise are the observational measurements for the speed of gravity? says: ...in 2013 a Chinese group built a model using Earth's tides that helped them narrow it down. ...
4
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1answer
87 views

Dark energy and light red shifting

When light is red shifted from distant galaxies, the photons have lost energy. When dark energy pushes objects apart, those objects have gained energy from a larger gravitational potential. Is the ...
1
vote
1answer
95 views

Could anything consume a small black hole?

Whenever I read about black holes, it is normally involving how they devour anything that comes too close... regardless of how big anything is. But what if it were a really small black hole vs ...
6
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1answer
65 views

Planets positions (azimuth, altitude) API

I'm looking for a simple API that will allow me to get positions of planets and the moon for a given date, location and time. Does anyone know an API like that? Any suggestions or alternatives would ...
10
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1answer
2k views

What is this “Table of astronomy” about?

I found this picture while looking for some tattoo ideas and would like to know what these sketches are supposed to mean. Im especially interested in figures 1, 21, 53 and 56. It appears to be ...
1
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1answer
58 views

Could Tabby's star be beamed by a neutron star's jet causing irregular star spots?

There have been some other questions here about what might cause the light curve dips of star KIC 8462852 as observed by Kepler Space Telescope. Here's one I haven't heard before: Could it be that a ...
1
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2answers
73 views

The size of Copernicus’ and Ptolemy’s corrections

I understand that both Copernicus and Ptolemy needed epicycles, but one might assume that a heliocentric system would need much smaller corrections to account for the non-circular motion of the ...
2
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1answer
55 views

What's the origin of Clyde Tombaugh's 9-inch Newtonian telescope?

Astronomer Clyde Tombaugh is shown in a now-famous photograph at the age of 24 with his "homemade" 9-inch Newtonian telescope in this image also shown in Elva R. O'Hara's Clyde W. Tombaugh: Farm Boy ...
5
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1answer
72 views

Why do transits of Earth across the Sun seen from Mars follow a pattern of occurring after 26, 79 then 100 years?

According to this answer transits of Earth across the disk of the Sun as seen from Mars: The (Arthur C.) Clarke story is quite correct. Earth (and Moon) would transit the sun from the viewpoint of ...
0
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1answer
48 views

Are red dwarfs (M dwarfs) known to be strong infrared sources?

If so, why? Are they known to be surrounded by large amounts of dust? Do they typically flare?
5
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1answer
91 views

Relativistic Mercury orbit around the Sun

My question is the following,would the scalar of precession of Mercury orbit be the same if Mercury orbited Sun in the oposit direction?
1
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1answer
75 views

Do gravitationally bound (e.g. orbiting) objects really resist the expansion of space?

Thinking about the expansion of space, it is commonly explained that gravitationally bound objects (like galaxies and galaxy clusters) will not be affected by the expansion of space (dark energy). I ...
0
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1answer
173 views

Will intergalactic travel be impossible in roughly 15 billion years?

Even if we (or aliens somewhere in the universe living at that time) somehow invent something that can go just short of the speed of light, will intergalactic travel still be impossible in roughly 15 ...
6
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1answer
95 views

Does light from the sun reach the surface of Venus

I am aware we have images from the surface of Venus from the Venera missions but I am not sure if those images are taken using the visible spectrum the human eye can see. This is why I was wondering ...
2
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1answer
26 views

How to interpret error of absolute magnitude of a star given data from wikipedia?

This Wikipedia page contains information about the star Spica in the rightmost table. A small snapshot of this table is below. In this table, the absolute magnitude is given as ...

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