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25 views

Name for pre-supergiant main sequence stars

The massive main-sequence stars which turn into supergiants--do they typically have special terminology for their classifications as do the less massive ones (which may be, e.g., "yellow dwarf" or "...
120 views

What exactly is interplanetary scintillation; what was the Interplanetary Scintillation Array looking for? Did it successfully observe any?

The Interplanetary Scintillation Array is the radioastronomy observatory (i.e. big antenna) where the first pulsar was discovered by then graduate student Jocelyn Bell Burnell through careful and ...
28 views

line of at least 20 lights moving across the sky [duplicate]

We watched a line of at least 20 satellites moving in a line across the sky. They were visible to the naked eye. Could they be Starlink satellites? We are in Sandbach, Cheshire. It was about 18.00 ...
29 views

A line of lights in sky [duplicate]

I just seen this in sky a line of stars probably satellites just wondering what they where and what they doing it was amazing never seen any like it
55 views

How to evaluate the fit of an isochrone to a stellar population?

Consider that I know the extinction, distance modulus, reddening, and metallicity for a particular star cluster. I need to determine it's age from isochrone fitting. After generating the required ...
237 views

Is moisture harmful to a Newtonian Reflector?

It is often cold outside, especially in the evening. So when I take my Newtonian Reflector back in my house, it starts condense. Can the water destroy my telescope? or the mirrors? Do I have to clean ...
293 views

What would the effects on or around Earth if Betelgeuse went supernova?

There's been a lot of news lately about Betelgeuse possibly exploding sooner than perhaps was expected. Some examples: Guinan, Edward F.; Wasatonic, Richard J.; Calderwood, Thomas J. (8 December 2019)...
3k views

Has great eyesight been necessary for astronomers?

In a different (but somewhat related) field, some baseball stars have been known to have "baseball eyes." That is, an exceptional ability to visually follow the trajectory of a 90+ mph baseball to a ...
56 views

Proper Terminology For Satellite Going Into Planets Shadow

What is the proper terminology for when a satellite or spaceship passes into a planet's shadow or night side? Is it crossing the terminator? Passing into eclipse? If there is a different name for ...
58 views

can gravity be faster than light in some specific cases? [duplicate]

This is a follow up question from If an event occurs at a point in space time what will an observer experience first, it's gravity or the light from it? This https://en.wikipedia.org/wiki/...
52 views

Lagrange points and the radius of the Hill sphere

(Disclaimer: I know the "Hill sphere" is just an approximation of something which isn't genuinely spherical.) In a two-body system, the approximate formula for the Hill sphere radius of the smaller ...
114 views

Why is this shooting star wavy or squiggly toward the end of it's visible streak

I was taking photos of some stars when I noticed this shooting star was wavy toward the end (start?) of it's trail. My cousin suggesting that it could be the CCD in my camera or as it spiralling as it ...
42 views

Do meteor showers start slowly each night?

Does the frequency of the number of visible meteors during a daily shower start off lower at the beginning only to increase as the night goes on or does the frequency remain the same for the entire ...
128 views

Kepler's equation and eccentric anomaly

From the wiki article about eccentric anomaly follows: $$\cos E = \frac{x}{a}$$ $$\sin E = \frac{y}{b}$$ where E - eccentric anomaly, a - semi-major axis, b - semi-minor axis, P = P(x,y) a point on ...
122 views

How can professional astronomers keep amateurs engaged given the ever-increasing power of modern telescopes?

There're many amateur astronomers out there who build their own telescopes, write their own data-gathering programs, and scan the night sky tirelessly. Sometimes they even happen upon new discoveries ...
59 views

Do all total solar eclipses have the ring of fire when observed from ground?

I was recording the phenomenon and then I soon realised that the ring of fire don't dissappear, is it because of the apparent size of the moon and sun as well as the relative distance so that every ...
31 views

Is the atmosphere of neutron star solid, liquid or gaseous state? [duplicate]

Neutron star has a thin layer of atmosphere consist mostly of hydrogen and helium and is about less than a metre thick on average, but what wasn't stated in many articles I read is the state of matter ...
26 views

Has the plasma amplification of electromagnetic waves in solar type-III bursts (or otherwise in stars) been explored further?

This answer to the SciFi SE question In the novel The Three-Body Problem, does the Sun's amplification of radio transmissions have a scientific basis? cites a 1995 paper published in Chinese Astronomy ...
45 views

Are there home-brew photometers for amateur observing of variable stars and are they widely used?

Comments on Why do these photometric observations of Betelgeuse look “quantized” in 0.1 magnitude steps? suggest that these are visual estimates, mostly (but not all) to 0.1 magnitude resolution. Are ...
70 views

Are there predictions of the distribution of matter at the end of time

Are there any theoretical predictions or "educated speculation" by cosmologists on how matter will be distributed at very, very distant times in the future? For example, will matter be: agglutinated ...
143 views

Does the dimming of Betelgeuse present any observational opportunities?

Recent photometry suggests that Betelgeuse has been dimming over the past three or so months, reaching the faintest V-band magnitude seen in modern observations. The changes are apparently even ...
10 views

Formula to Compute sigma8 for correction in non-linear regime

I try to explain my issue on this forum since it seems to be appropriate. I need to apply a correction on $\sigma_{8}$ between linear and non-linear regime to keep it fixed (I make change the values ...
65 views

Does a photon honor the causality principle?

We know that the faster you move, the slower your time is perceived from an external observer and the space along the direction of the movement shrinks. Photons, having no mass, move at the speed of ...
76 views

Does the gravity oppose to the Universe expansion?

I'm trying to understanding the very basic of the current cosmology. I searched in the old questions but I found nothing that answers specifically to my questions. As far as I understand, we have to ...
60 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 ...
13 views

How often are wedge prisms used to correct chromatic effects of atmospheric refraction?

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 ...
94 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 (...
3k views

What observation can be expected on LIGO if any when Betelgeuse goes supernova?

What observation can be expected from the LIGO† gravitational wave observatory if any when Betelgeuse goes supernova? Could we know that Betelgeuse has gone supernova before we see it light up our ...
72 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 ...
34 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 ...
67 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 ...
41 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 ...
37 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 ...
22 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 ...
54 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)?
29 views

Stellar interior structures

im really confused on how i relate mass to radius of a star with a non constant density. more specifically i cannot seem to find an equation that states how density varies throughout a main sequence ...
235 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 ...
166 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 ...
30 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 and density varies with the distance but does ...
20 views

How do we differentiate an eclipse, transit and occultation? [duplicate]

Different online resources seems to be confusing in this respect. What actually differentiate an eclipse from transit and occultation? The involvement of shadows, relative apparent sizes of the ...
42 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 ...
86 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 ...
154 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 ...
53 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 ...
161 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 ...
41 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,...
56 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 ...
35 views

Skyfield Subpoint() usage

Is subpoint() in skyfield used for finding subsolar point?, i cant find examples in this link subpoint. How can i use it to find ...