All Questions
14,649
questions
1
vote
0
answers
130
views
Why do these photometric observations of Betelgeuse look "quantized" in 0.1 magnitude steps?
The most interesting question related to this Will Kinney tweet would be what's going on with Betelgeuse? but I can't help but wonder why much but not all of the photometric data is clustered in ...
5
votes
1
answer
130
views
When are wedge prisms used to correct chromatic effects of atmospheric refraction? (atmospheric dispersion)
Atmospheric refraction (shown below) happens because Earth's atmosphere has an index of refraction that differs from unity.
@MikeG's comment mentions that this refraction would have a chromatic ...
4
votes
1
answer
126
views
If an event occurs at a point in space time what will an observer experience first, it's gravity or the light from it?
Let's assume a person is close enough to an object in space time to be able to observe it's gravitational effects and the light coming from it.
If that object suddenly pops out of existence (...
23
votes
2
answers
3k
views
What observations can be expected on LIGO if any when Betelgeuse goes supernova?
What observations can be expected from the LIGO† gravitational wave observatory if and when Betelgeuse goes supernova?
Would we know that Betelgeuse has gone supernova before we see it light up our ...
5
votes
2
answers
240
views
Scientific possibility of stationary moons for a writer of fiction
I tried to do some research to find an answer for this question before posting this but didn't find anything that I could sink my teeth into.
I was wondering:
if it would be possible for a planet to ...
0
votes
0
answers
144
views
Does the average person in China know the constellations by the traditional Chinese system or Hellenic designation
As discussed in the International Dunhuang Project website, in traditional Chinese astronomy "the Chinese sky was divided into five great regions or palaces called gong 宫," and "Chinese astronomers ...
0
votes
2
answers
2k
views
Size of the Universe before the Big Bang [closed]
I can't understand how all the matter contained in the Universe, was contained in an area the size of a grapefruit before the Big Bang ? How could so much matter have been compressed in such a tiny ...
1
vote
1
answer
193
views
Why is Io's volcanism chemically so different from Earth's?
Volcanic gases on Earth are mainly water, carbon dioxide and sulfur dioxide, but on Io there is a notable absence of water and carbon dioxide in volcanic gases, since sulfur dioxide is the dominant ...
0
votes
1
answer
60
views
mirror image of the earth in the past [duplicate]
For example, if there was an object somewhere in the room, say 100 light years away, which would have to be very large and have the surface of a mirror, you could theoretically point the telescope at ...
5
votes
0
answers
140
views
What is the surface feature of the mesas in the Noctis Labyrinthus on Mars?
Caveat-my knowledge of geology is limited.
Is it known what is the surface like on the larger mesas in the Noctis Labyrinthus? I trust the very smooth looking surface on this mesa is a product of ...
3
votes
2
answers
1k
views
How to convert apparent visual magnitude to SI units?
How do I convert the apparent visual magnitude of astronomical objects to SI units (lumens)?
9
votes
1
answer
377
views
How are neutrinos produced in blazar jets?
I was watching the press release about measuring neutrinos and gamma rays from a distant blazar. One of the presenters mentioned that the neutrinos are associated with very high energy protons caught ...
3
votes
3
answers
253
views
What's the cheapest lens to buy for showing ISS to a flat earther?
Recently I entered a discussion with someone that has a relatively popular YouTube channel which says among other things that the earth is flat. I said that earth isn't flat because you can see the ...
5
votes
1
answer
176
views
Correlation between stellar mass and galactocentric distance
As we move away from the centre of, say, a spiral galaxy, is there a relation between the stellar mass and distance?
I know the how the stellar abundance number and density varies with the distance ...
1
vote
1
answer
52
views
Is there a general term used to identify the high flat features within Noctis Labyrinthus on Mars?
At the western end of Valles Marineris, where it mets Noctis Labyrinthus (highlighted section of image)
there are a series of flat geological formations between the canyons.
Is there a unique term ...
-1
votes
2
answers
116
views
Visibility of a planet on the other side of the Sun
Context: I've been having a discussion with my vectors and mechanics professor (course Mathematics BSc) about a problem on a recent coursework. The following is the model I came up with. I'm not an ...
2
votes
6
answers
525
views
Would planet explode without gravity?
A planet (as well as a dwarf planet) must, according to the IAU definition, have sufficient mass to assume hydrostatic equilibrium (a nearly round shape). Does it mean they would break apart or ...
3
votes
1
answer
130
views
How does the field decay of a magnetar power the emission of high-energy electromagnetic radiation?
In Space.com's Dr. Pulsar and Mr. Magnetar? 2 Star Types May Turn into Each Other (and in the linked video) "Tom Prince, a physics professor at the California Institute of Technology and a senior ...
2
votes
2
answers
366
views
Why are we so quick to proclaim the geological inhospitability of other planets based on extremely minimal information?
Now, I'm not questioning claims that any planet in the Solar System is atmospherically or externally inhospitable, but claims made that other planets have geology that is extremely hostile to ...
3
votes
1
answer
78
views
How long do solar eclipses last on Metis?
How long does Jupiter obscure the sun, from the perspective of Metis, the innermost moon of Jupiter?
In other words, how long does Metis remain in the shadow of Jupiter?
If it varies by time of year,...
2
votes
1
answer
1k
views
Help with Converting Right Ascension and Declination into 3D Vectors
Using the Right Ascension and Declination values from the HYG Database from The Astronomy Nexus:
Right ascension is measured in hours and declination is measured in degrees.
1 - Convert right ...
14
votes
1
answer
582
views
At Mars' equator how long does twilight last?
With Mars' thinner atmosphere I'm assuming twilight would not last as long compared to the duration on Earth. Has there been any determination of the length of twilight on Mars at the equator or any ...
0
votes
1
answer
99
views
Extinction and reddening dataset
Where can I find a dataset containing the interstellar reddening and extinction values for all globular clusters, preferably in the HST/WFC3 system.
1
vote
1
answer
66
views
Data for spectrum of Wolf-Rayet stars
I'm looking for a way to access the data used to produce these plots for instance. These plots show the spectrum of various Wolf-Rayet stars. I found a few websites where you have some informations on ...
2
votes
1
answer
100
views
Elliptical galaxy morphology
I understand what differentiates elliptical galaxies from spiral, lenticular, and irregular galaxies. What is the difference between a compact elliptical (cE) galaxy and a dwarf elliptical (dE) galaxy?...
4
votes
1
answer
182
views
What can be learned from low frequency radio astronomy available outside of Earth's ionosphere?
As discussions and answers to How large does refraction become in radioastronomy? point out, it is difficult to do radio astronomy much below 30 MHz (or 10 MHz depending on how aggressive you are in ...
6
votes
1
answer
115
views
Voyager 1 and 2 detected a 20-fold increase in plasma density, significantly different refractive index?
As reported by Nature.com, Voyager 1 and 2 detected a 20-fold increase in plasma density going from the heliosphere out to interstellar space. Does that 20-fold difference in density imply a ...
3
votes
3
answers
623
views
Optics: "Airy disc" and size of objects
Jupiter has a minimum brightness that is brighter than stars. Is the reason an “airy disc”, concentric rings as a diffraction effect, is seen around stars and not Jupiter because Jupiter has an ...
11
votes
1
answer
219
views
Is it possible to see stars that are gravitationally lensed by the sun from the ground?
Roughly 100 years ago, Eddington confirmed Einstein’s general relativity theory by photographing stars behind the obscured Sun during a total eclipse.
A coronograph is a device that mimics what ...
3
votes
0
answers
547
views
What is the difference between spectroscopy, spectrography and spectrometry?
Spectroscopy is the study of spectra, spectrography is the writing of the spectra, and spectrometry is the measure of spectra. So from an etymological perspective, there is no real difference between ...
3
votes
0
answers
61
views
Would Martian sunrise/sunset look the same at the Thaumasia Plateau as the rovers' photographs?
If observing the sunrise or sunset, with the naked eye, from the Thaumasia Plateau (app. 260°, -10°), 6 kilometers above Mars elevation zero,
would it have the same blue hue as the images of the ...
1
vote
0
answers
35
views
Stellar aberration, any prism effect?
In stellar aberration, is there any prism effect, chromatic aberration?
7
votes
2
answers
238
views
Are meteors visible on Mars?
If a person were standing on the surface of Mars, under ideal viewing conditions for seeing a meteor: no clouds, the sun has long set, would a meteor be visible to the naked eye considering how thin ...
1
vote
3
answers
345
views
Comet 289P/Blanpain sudden outburst?
So Sky Safari has shown that comet 289P/Blainpain has had a sudden increase in brightness, and is currently sitting at mag -1.4!!! Last week it was sitting at +15. It is due to reach Perihelion on ...
1
vote
0
answers
127
views
How can I get the exact time of each zodiac every year?
I want to make a calculator for Chinese New Year calendar. There is a rule that a leap year happens if the eclipse happens before each zongqi (equivalent to the middle of zodiac sign, ie. 15º, 45º, ...
21
votes
1
answer
585
views
Can we detect pulsars that aren't "pointed" towards us?
A pulsar is a highly magnetized rotating neutron star that emits beams of radiation through its magnetic poles, in the direction of the Earth. This makes it seem to pulse, as seen from Earth. There ...
3
votes
0
answers
102
views
Does the axis of solar system precess during it's motion in the Milky way galaxy?
The plane of solar system makes an angle of 60° with the plane of galaxy. So, the axis of solar system should make 30° angle with the galactic plane. Like the axis of Earth precess over a long period, ...
0
votes
0
answers
41
views
What is the typical chemical composition of the most common asteroid types?
I'm trying to make a semi-scientific accurate game where you can find/mine asteroids. I want the composition of asteroids, and how common they are to be correct. Or at least as close to correct as ...
0
votes
1
answer
948
views
What's the difference between semi-major axis and apoapsis?
The semi-major axis is half of the diameter of the major axis of an ellipse by definition. So how does that make it any different from apoapsis, the furthest point an object is from a parent body in ...
1
vote
1
answer
252
views
Can Kepler's 3rd Law be applied in higher dimensions to describe orbits (quadric surfaces)?
Motivation for asking:
The 2-D orbital path of a celestial body revolving around another celestial body due to the force of gravity can be described by a conic section; this is the curve formed by ...
2
votes
1
answer
189
views
Does Earth's magnetic field become stronger when a solar flare hits?
This curiosity arises as follows: when ejecta from a strong solar flare hits Earth, will the Earth somehow counter its impact with a stronger magnetic field.
Or, earth's magnetic field as limited ...
1
vote
1
answer
200
views
What reference frame do age-of-the-universe calculations assume?
I'm thinking, in particular, about general relativity. When we speak, for example, of neutrino decoupling, what do we mean when we say this happened in the first second after the Big Bang? Do we mean ...
11
votes
1
answer
1k
views
How can I hear (or at least detect) a pulsar at home?
Scott Manley's video Using Relativistic Raytracing &X-Rays To See Detail on Surface Of Neutron Star talks about X-ray measurements using the NICER X-ray telescope attached to the International ...
8
votes
1
answer
146
views
Anecdote of an astronomer looking for correlations in antipodal pairings of stars; what am I remembering?
The question Are the stars distributed in uniform distribution, on the celestial dome, with respect to brightness? brings to mind a different study that I vaguely remember hearing about a while ago, ...
0
votes
0
answers
37
views
How to use the APARM, BPARM and CPARM of REGRD task in AIPS?
I plan to regrid a 500 by 500 image in B1950 to 500 by 500 in J2000 using the AIPS task REGRD. How to proceed?
20
votes
2
answers
6k
views
Are the stars distributed in uniform distribution, on the celestial dome, with respect to brightness?
Has there ever been a statistical analysis of the distribution of stars in the sky (on the surface of the celestial dome), by brightness? I want to know if they are uniformly distributed.
For example, ...
1
vote
1
answer
552
views
Delay of Moon passing a defined meridian each day
On the website Lunar Synodic Curve a nice image of an Moon analemma is shown together with an explantion on the reason why for the different phases of the Moon the images have to be taken with 24h ...
2
votes
1
answer
3k
views
Semi-major axis in a binary star system
The semi-major axis a here,
what exactly does it represent? Point it out in the image below.
2
votes
2
answers
430
views
Finding Quintuple Planetary Alignments with SkyField
I am working on a python script that will use the SkyField and SciPy libraries to find quintuple planetary conjunctions and their corresponding constellation location. Specifically I am looking for ...
4
votes
1
answer
123
views
Using a differential force in the derivation of hydrostatic equilibrium in a star
I've been banging my head against this particular derivation of hydrostatic equilibrium in a star for the last few days, from Carroll and Ostlie's Introduction to Modern Astrophysics (2nd ed. p. 286):
...