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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 ...
uhoh's user avatar
  • 31.1k
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 ...
uhoh's user avatar
  • 31.1k
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 (...
raptorAcrylyc's user avatar
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 ...
Lord Loh.'s user avatar
  • 339
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 ...
user42510's user avatar
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 ...
Bob516's user avatar
  • 1,467
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 ...
Peter U's user avatar
  • 1,619
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 ...
URIZEN's user avatar
  • 387
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 ...
Dani's user avatar
  • 1
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 ...
Bob516's user avatar
  • 1,467
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)?
Nicole Sharp's user avatar
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 ...
PSR-1937-21's user avatar
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 ...
PPP's user avatar
  • 133
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 ...
Khurana's user avatar
  • 173
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 ...
Bob516's user avatar
  • 1,467
-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 ...
mjc's user avatar
  • 109
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 ...
Leos Ondra's user avatar
  • 1,074
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 ...
uhoh's user avatar
  • 31.1k
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 ...
Grant Hartlage's user avatar
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,...
cowlinator's user avatar
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 ...
SidS's user avatar
  • 225
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 ...
Bob516's user avatar
  • 1,467
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.
Hrsht's user avatar
  • 333
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 ...
Laurent Hayez's user avatar
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?...
Stellae Incognitae's user avatar
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 ...
uhoh's user avatar
  • 31.1k
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 ...
Gurnt's user avatar
  • 61
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 ...
Stark's user avatar
  • 31
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 ...
usernumber's user avatar
  • 17.5k
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 ...
usernumber's user avatar
  • 17.5k
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 ...
Bob516's user avatar
  • 1,467
1 vote
0 answers
35 views

Stellar aberration, any prism effect?

In stellar aberration, is there any prism effect, chromatic aberration?
Viktor's user avatar
  • 11
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 ...
Bob516's user avatar
  • 1,467
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 ...
MCG's user avatar
  • 795
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, ...
Hoy Cheung's user avatar
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 ...
usernumber's user avatar
  • 17.5k
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, ...
Radium's user avatar
  • 133
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 ...
Rene Pot's user avatar
  • 101
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 ...
Will's user avatar
  • 31
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 ...
user avatar
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 ...
Ubi.B's user avatar
  • 221
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 ...
MathAdam's user avatar
  • 163
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 ...
uhoh's user avatar
  • 31.1k
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, ...
uhoh's user avatar
  • 31.1k
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?
user30981's user avatar
  • 199
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, ...
DrZ214's user avatar
  • 1,960
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 ...
Rainer's user avatar
  • 113
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.
d1ep's user avatar
  • 21
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 ...
Joshua Besneatte's user avatar
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): ...
ygtozc's user avatar
  • 43

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