How is it different to take 100 photo's of an object versus copy-paste 1 photo 100 times. Is the amount of light 'captured' the same when the images are stacked? How would this affect the stacked image?

I'm a beginner in astrophotography and have done my first 3 images with about 100 stacked photo's each, but this got me thinking.

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Cheers

I get why the harvest moon rises earlier than expected. But why can you use the fact of the equinox to predict the moon is mid cycle (moving with largest northward component)? Isn’t this based on the solar calendar, so the cycles would be expected to drift apart?

I just tried out my new 8" dobs-onion telescope on a couple of stars and a random fairly dark bit of sky. I am never going to be the same. I thought I might puke. This is ridiculous.

I'm not sure what I expected from the scope but it wasn't a minor crisis and a cold sweat from a random bit of sky. I feel like I'm not quite the same after seeing that. I had a voiceless scream to myself.

The sheer scale of the universe is NONSENSE! I feel like I've seen something I shouldn't. I feel total reverence for the horrifying beauty and scale of the universe.

I still feel a bit funny. I bet there's a word for it

Good day, Reddit! I hope this message finds you all well.

I’m currently educating myself on the field of astronomy as part of my research for a novel, and in my limited studies thus far, I’ve noticed what I can’t help but describe as an inconsistency in the metrics for the classification of main sequence stars. With some of the sources I’ve consulted online, there seems to be some discrepancy on what surface temperature is considered to represent the dividing line between the high end of Class B main sequence stars and the beginning of Class O stars (I’ve seen surface temperature thresholds as low as 28,000 K and as high as 31,000 K being used to distinguish the dividing line between Classes B and O stars). Is there a definitive, commonly accepted surface temperature threshold which marks the classification of a Class O star, or is this standard more flexible than it would appear? I’m trying to accurately convey these figures and am looking for guidance.

I have a home planetarium - the sega homestar flux (highly recommend). Some of the plastic discs now have scratches that sadly show up when projected. I looked online for general advice on how to buff away scratches on plastic, and the general recommendation is to use a light abrasive like baking soda. However, I wonder if the guidance differs when we’re talking about planetariums since everything is magnified. I wonder if doing this will just cause more micro scratches that are visible when projected.

Any suggestions or advice?

To what extent can hobbyists observe exoplanets, especially to be able to learn about or get data about them that might be useful as citizen science? I'm new to the interest, I don't even have a telescope yet (I don't have a car to feasibly take it somewhere dark, which I easily could if I did) but I want to spend the money on something I can use for an interest. Looking at nebula is cool and all but it's exoplanets that really interest me. I know many will say it's about budget but I don't really have a budget in mind, I'll just save up to get what meets my needs, so what's the lowest budget for observing, in any capacity, exoplanets, from which I can just increase my budget to meet my needs? Thanks in advance

I don't know if this is the right place but I'm looking for a comprehensive list of the classing of stars sets and subsets. I've tried googling it but it's very hard to even word a question like this in Google. I either get a huge list of the actual names of the objects (ex: Milky Way instead of Galaxy) with no indication of wether one is a set or subset of the other, or I get a list of every type of astronomical object. The only one I found was very vague and didn't list wether one was a subset of another or just a smaller version of it. I'm only looking for groups of stars.

The the diameter of a black hole is proportional to the mass, R = 3M here:

https://chandra.si.edu/edu/formal/math/7Page81.pdf

Consider 3 black holes of diameter 1. They all will have the same mass.

3 spheres of diameter 1 can fit into a sphere of diameter 3 without touching each other,

Imagine 3 black holes of diameter 1 moving towards the same point P. The will enter the sphere of diameter 3 with the P as the sphere's center. Since they are inside this sphere, a black hole containing all 3 has formed. But the 3 black holes have not yet collided. And, given the limit of the speed of light how can the event horizon form simultaneously on the surface of the sphere?

Or would they rip themselves apart beforehand?

Hi all

I’m writing my thesis in astrophysics right now. I’m trying to fit a Kepler orbit to the newly discovered star S4716. However, when trying to estimate the reduced chisq value I end up getting a value of 206. I use the same limitations and constant as Peißker et al ( https://iopscience.iop.org/article/10.3847/1538-4357/ac752f ). On the other hand , the plot looks decent (See attached files named S4716_Peissker).

Could the error be the lack of data points (21)? Or something totally obvious that I’m not seeing?

There are 20 datapoints where 4 of them have an error of 0.5 i.e. the fit and chisq are totally dominate by these poins and looking at the plot and interpreting a bit, I should end up with a chisq < 2 more or less….

My code can be found at github:

GitHub - donfup/S4716: Fitting data to S4716Fitting data to S4716. Contribute to donfup/S4716 development by creating an account on GitHub.https://github.com/donfup/S4716

I have included a fit I did for S2 which works perfectly fine - maybe its useable for inspiration?
The output of my code is attached.
Can anyone see what I’m doing wrong in my calculation of the chisq-value? All help is much appreciated!

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ORIGINAL POST: https://www.reddit.com/r/Physics/comments/11qefa6/stellar_orbits_s4716_and_chisq_values/?utm_source=share&utm_medium=web2x&context=3

Hi everyone, I'm organising a meteor shower event for the Eta Aquarids Meteor Shower, for a large group of people. However, we are all new to meteor shower watching. Information websites state that the meteors peak on the 7th of May at 02:00am AEST, however our group cannot stay out that long. If we were to watch for meteors at 10pm AEST on the 6th of May, would they still be visible in the sky? Thank you everyone ^^

I'm planning on being an astronomer and need a little advice. I see lots of online discussions about how it can be a little difficult to get into a PhD program and even if you do, its very difficult to get to that permanent astronomer position with any type of employer. Despite this I think this is still what I must do so my question is what are the things I can do as I go through this process to help maximize the chance that I will eventually get to one of these permanent positions? I'm just starting out as a college freshman so I got some time.

P.S. In trying to comply with rule 4, I've tried to do research on this other places on the internet but haven't found much. Mostly because its hard to find search terms that offer decent returns.

I've heard that the common hypothesis for why Uranus is cold and on its side is because a nasty collision drained the planet of its heat but if that were the case, why didn't the same thing happen to Earth when Theia collided with it? Wouldn't we have a mostly cool core with little geologic activity?

Please be kind, I'm an average layman. Our Moon rotates around our Sun. Our Sun rotates around Sagittarius A*. Does our Galaxy rotate around something beyond our imagination? If so, are we even more insignificant than we thought? Edit. Short explanation please. Edit. Sorry, Rotate means Orbit

Amazingly, the article was more than one sentence long.

So assuming that the universe is infinite, that would mean that infinite possibilities are possible within it, so that would that mean that a planet with the exact same mass as earth and the exact same topography and exact same layout as earth, along with chemical composition and atmospheric conditions could exist? Right? I'm just confused with the possibilities of an infinite universe and a little bit drunk to be honest.