All Questions

2
votes
1answer
39 views

Helioseismology of the Sun, what is actually measured?

Wikipedia's article Helioseismology outlines several ways to analyze, data but is fairly thin on the nature of the measurements themselves. Are there hundreds or thousands of high resolution ...
3
votes
0answers
77 views

Can any type of stars be contact binaries?

In this article Shortest distance between stars it is mentioned that Some double stars can actually be in contact with each other. This occurs when a red giant star has a white dwarf star ...
1
vote
1answer
57 views

Transform asteroid rotation to heliocentric ecliptic coordinates

I'm working with data from the DAMIT database of asteroid shape models. I'm adding them to a visualization in which the sun is at [0, 0, 0] and the X, Y axes constitute the ecliptic plane of the ...
7
votes
2answers
933 views

Properties of low-mass stellar remnants vs the Earth

How does the Earth differ from a (low-mass) stellar remnant, which has stopped fusion and the outer layers of which have been blown away? Could a stellar remnant end up with a similar relative ...
1
vote
1answer
54 views

Could a rocky rogue planet get trapped in the orbit between Earth and Mars?

I know it's extremely unlikely a rogue planet passing by there, and I know the size of rocky planets can vary a lot (IIRC there is a rocky planet 5 times the size of Earth) but in any hypothetical ...
3
votes
1answer
91 views

Just how fast is a Fast Radio Burst thought to be?

According to Wikipedia;s Fast Radio Bursts; Frequencies and dispersion are recorded they The component frequencies of each burst are delayed by different amounts of time depending on the ...
1
vote
0answers
51 views

Are there any ways in which the light time difference between the center and the edge of the solar disk is noticeable?

In the ABC News video New space discovery has astronomers buzzing at about 02:30 Dr. Hakeem M. Oluseyi explains that the shortness of FRBs (before dispersion) suggests a compact source size and ...
7
votes
2answers
3k views

Did I see a mentionable event in Germany early morning on 6th of February 2019?

Around 6.15am (GMT + 1) on the 6th of February 2019 I was looking out of my window somewhat north, when I saw something one would probably call a shooting star. The features were: A magnitude I ...
4
votes
1answer
72 views

Is an elliptical orbit around a black hole, or an orbit consisting of three bodies (including the black hole) possible?

If this is possible, would it then lead to an object undergoing varying time dilation (predictable variation with elliptical and random variation with three body)?
1
vote
1answer
50 views

Do planetary magnetic fields slow the movement of conductive extraplanetary moving objects via induction?

A fixed magnetic field will induce an electrical current in a conductive object moving through the field. The strength of the eddy currents will depend on the shape and composition of the conductor ...
2
votes
1answer
30 views

Happy lunar new year! When will “sunset” happen for Chang'e-4 and Yutu-2?

Firecrackers all night and all libraries being closed here are two good indicators to a nerd like me that Lunar New Year has come again, and that means that it's the beginning of a lunar month and new ...
2
votes
1answer
55 views

How to convert sidereal time to local time?

I came across something that won't let me go, but no matter how much I calculate (which I do not like), it doesn't seem to work. Also: I've used so much apps and links already to convert, but it doesn'...
-1
votes
1answer
104 views

Can light be curved due to heavy gravitational force?

Lets suppose there is a huge planet having large amount of gravitational pull, then will the light passing through the planet get attracted towards it.
5
votes
0answers
58 views

Is the Ordovician meteor event detectable in the lunar cratering record?

Approximately 468 million years ago there were a large number of L-chondrite meteorites falling to Earth. This is called the Ordovician meteor event and was probably the result of a large collision in ...
3
votes
0answers
45 views

Did Eudoxus describe the eclipitic on his sun motion model?

In the description of Eudoxus’s model for the sun he says one the three circles which describe solar motion is “the circle which runs along the middle of the zodiac”. Does this refer to the ecliptic ...
0
votes
2answers
49 views

How to convert celestial Coordinates with a radius, to max and min celestial coordinates?

I am writing a piece of python code to convert right ascension and declination with a given radius to minimum and maximum right ascension and declination. I firstly can't understand why the min and ...
0
votes
0answers
30 views

Is albedo ever greater than unity? How is it calculated for various surface diffusivities and specular reflection? [duplicate]

I'm trying to understand how albedo would be calculated for a body with well-characterized surface reflectance properties, so that it's absolute magnitude could be defined. One could argue that this ...
3
votes
1answer
40 views

Stellar nurseries in the “Shedding New Light on the Whirlpool Galaxy” video

Captions in the Hubble Space Telescope YouTube channel video Shedding New Light on the Whirlpool Galaxy say: (visible) Along the dark dust lanes, bright pink nebulae are the birthplace of new stars....
1
vote
2answers
54 views

What is the difference between albedo, absolute magnitude or aparent magnitude?

What is the difference between albedo, absolute magnitude or aparent magnitude? I can’t really tell what’s the difference between them.
4
votes
1answer
74 views

Do tides occur on planets like Neptune, having water?

I mean, we experience tides here on earth because of combined effect of gravitational field of moon and sun. So I thought that tides could also occur on other planets. Let us consider Neptune where ...
0
votes
1answer
21 views

How to collect photometric data for WW Aur

I have problem with the collect of photometric data for star WW Aur. I can't find any file with HJD and mag column beside this one on Vizier: http://cdsarc.u-strasbg.fr/viz-bin/cat/J/MNRAS/363/529. I ...
2
votes
1answer
79 views

Geographical Point of the Sun

I want to draw a Sun in a 3d scene, so I figured the easiest way would be to calculate the latitude and longitude of the point perpendicular to Sun position and then just move it "up". As a starting ...
8
votes
2answers
71 views

How do we know that an exoplanet is tidally locked to the parent star?

Often in discussing exoplanets we hear that they are close to the parent star (usually a red dwarf) but then there's a caveat that the planet is tidally locked to that star and that that fact severely ...
1
vote
1answer
23 views

Luminosities and Apparent Brightness of Two Stars of which one is 8 times the distance of the first star [duplicate]

Suppose two stars have the same apparent brightness, but one star is 8 times further away than the other. What is the ratio of their luminosities? Which one is more luminous, the closer or the further ...
0
votes
1answer
40 views

The Luminosity of two stars with same brightness but at different PC away

Stars A and B are both equally bright as seen from Earth, but A is 120 pc away while B is 24 pc away. Which star has the greater luminosity? How many times brighter is it?
2
votes
1answer
105 views

Shouldn't we not be able to see some black holes?

Whenever there is a picture of a black hole, (even though they are artist depictions, this is how they are described) most are shown kind of in a flat disk like this. My question is, why do we see ...
5
votes
3answers
50 views

Do tides occur on planets like Neptune, having water?

I mean, we experience tides here on earth because of combined effect of gravitational field of moon and sun. So I thought that tides could also occur on other planets. Let us consider Neptune where ...
1
vote
1answer
39 views

Ensemble average VS spatial average for a cosmological density field

I'm studying statistical properties of a cosmological density field and I have some doubts; in the following quote and pictures you can see what my problem is: A fundamental limitation arises in ...
0
votes
1answer
46 views

If the axis of the Earth was through Greenland, what would the north celestial pole be? [closed]

If the axis of the Earth was through Greenland, what would the north celestial pole be?
2
votes
0answers
55 views

Correction to inverse square law for cosmology

While reading about the discovery of quasars and the spectroscopic analysis of 3C 273 in this paper by Maarten Schmidt, I came across the following quote: At these distances, corrections to ...
2
votes
1answer
30 views

How to obtain distance modulus and Total extinction from Isochrone fitting to CMD?

This is my first post here. I am studying the following article: https://arxiv.org/abs/1901.03574. On Page 5, Sec 3.1, the authors are presenting their results they obtained via Isochrone fitting ...
2
votes
1answer
136 views

Do falling bodies ever slow down?

I've had some discussions recently about black holes, and the issue of infalling bodies taking forever to reach the event horizon. That's essentially what Einstein said in his 1939 paper on a ...
1
vote
1answer
38 views

Eclipse Changes Directions?

How could the lunar eclipse of January 20, 2019 begin from bottom to top and then finish from left to right? Here's the video of it's progression's directions. https://www.youtube.com/watch?v=...
1
vote
0answers
17 views

How to measure the effect of the propellants to the thrust of the ion engines in a diy experiment? [migrated]

I have a science project about how different propellants affect the thrust of an Ion engine. So I have 2 questions: How can I measure the thrust of a diy ion engine? (technique or tool that I need to ...
4
votes
2answers
75 views

Is it possible to see a spacecraft orbiting the moon with a pair of binoculars?

On this clear early morning over London, I was studying the moon with a pair of binoculars and noticed a tiny dot of light that appeared to trace a slow orbit around the moon. I reckon it moved ...
1
vote
0answers
43 views

Regarding the VizierR catalogue

I want to build a Machine Learning model to approximate effective temperatures of stars based on their B-V index but there aren't that many catalogues that include that. I came across the Vizier ...
5
votes
1answer
46 views

How many horizontal branch stars are within 2 kpc of the sun?

For my research purposes, I am wondering how many horizontal branch (HB) stars are within 2 kpc of the sun? I tried to find some with the Gaia DR2 data with a magnitude cut that leaves HB stars out ...
5
votes
3answers
156 views

How do we know distant stars still exist

The Pleiades are 450 light years away. Thus when we see the twinkle in the night sky the light that hits our retina emanates from the year 1569 or so. On that proviso; how can we be sure that the star ...
1
vote
0answers
46 views

What happened to the third planet in the Kepler-47 system?

In 2012, the discovery paper for the multiplanet circumbinary system Kepler-47 mentioned a potential third transiting planet in the system: A 0.2% deep transit-like event is present at time 2,455,...
1
vote
1answer
46 views

does the orientation of orbital plane of our solar system rotate with the galaxy

As I understand it, our solar system travels through the milky way with the orbital plane tilted about 60 degrees so that we are sort of traveling in the direction of earth's north. My question is if ...
2
votes
0answers
20 views

Change in axis of the Earth if the Moon would dissappear [closed]

I read that, if the moon would not be there or if it would dissapear or be destroyed it could cause the earth to rotate into a possible axis of 45° degrees. Because it would be missing the ...
0
votes
0answers
30 views

How many amateur telescopes are looking for serendipity in a coordinated fashion, on average?

I can't read the Nature Astronomy article A kilometre-sized Kuiper belt object discovered by stellar occultation using amateur telescopes because the library I use doesn't subscribe electronically. ...
16
votes
2answers
3k views

Could stars form outside of galaxies?

Is it possible for there to be a dense enough nebula to form stars outside of any galaxy? Does a galaxy have a minimum size to produce stars? Or could you have a few dozen stars clustered together by ...
-1
votes
0answers
22 views

What is the evidence that the universe began in a hot, dense state 13.8 billion years ago? [duplicate]

What are the evidences to prove big bang theory and proof how the universe began in a hot, dense state 13.8 billion years ago?
2
votes
1answer
73 views

What causes Titan a moon to have a denser atmosphere than that of a Mars?

I'm wondering about Mars and Titan. If Mars is larger than Titan how come it lost most of its atmosphere? Mars also has a magnetic field while Titan doesn't. Yet Titans atmospheric pressure on the ...
15
votes
3answers
1k views

Infalling observer could never cross Black Hole event horizon? [duplicate]

I have an interest in cosmology, but I would no way consider myself an expert. It would be great if the more knowledgeable contributors would be able to answer the question I have posed. The intense ...
5
votes
2answers
155 views

Could a moon orbit an Earth size planet in such a way as to create a solar eclipse lasting for several weeks from start to finish?

Is it theoretically possible for a moon to orbit a planet (let us say Earth size, mass and solar distance) in such a way as to create a planet-wide solar eclipse lasting several weeks? These are my ...
1
vote
0answers
25 views

Surface Conditions

Planets like Saturn & Jupiter are called "gas giants"--does that mean that there is no surface to walk upon? Though some source of gravity is required to hold the gas in place, isn't it? Venus: we ...
0
votes
1answer
57 views

If Mercury and Venus where to collide would it make a habitable planet? [closed]

I have been wondering for a while now about a scenario of where if you combined Venus & Mercury would it be habitable if located in the goldy locks zone? I have found in my little research that ...
0
votes
0answers
30 views

If I point a camera at a “+x” visual magnitude object, how to estimate how many e- (carriers) are produced per second?

In this answer I estimated that if a DSLR (digital SLR) camera with an aperture of 40 mm were pointed at a satellite in geostationary orbit with a visual brightness of about +11 magnitude, it would ...

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