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1500 questions
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Where in a star are the spectral absorption lines formed?
This question was inspired by a recent Cool Worlds video "The Star That Shouldn't Exist", in which one of the speculative solutions to Przybylski’s Star's strange spectrum is aliens "salting" the star with heavy elements. This has raised much…
asgallant
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Are spacecraft visits to Uranus and Neptune hard to plan?
Until today, Voyager 2 remains the only spacecraft to visit these planets. Are spacecraft visits to these planets hard to plan or develop?
anon
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Is the amount of dark matter the same as you look back through time (further away from earth)?
In the hope that it may provide information on the development/evolution (if any) of dark matter over time, are there any differences (eg. in structure or concentration) in the dark matter at large radial distances from earth compared with closer…
Zinn
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Proportion of Lunar Fraction in a Year
I grabbed a year of lunar fraction data from the USNO and binned the counts to find the shape of the curve as below
My understanding of lunar fraction was that 0.5 does not distinguish between the direction as it is a cycle from 0 (new moon) to 1…
Zac Warham
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Are multiple stars actually more common than singles?
In the book by Neil Tyson & Michael A. Strauss & J. Richard Gott titled "Welcome to the Universe: An Astrophysical Tour" there is a sentence that starts: "Since more than half the stars in the galaxy are in binaries, ... ". But is it really…
Jimmy Bionic
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How is a Planet's Moment of Inertia Measured Remotely?
In the July 2023 issue of Sky & Telescope there is an article titled Sights Set on Uranus. In that article the following statement is made:
Since the 1930's we've suspected that Uranus and Neptune are made
mostly of ice. (Ice refers to materials…
GrapefruitIsAwesome
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Are gravitational waves emitted equally in all directions?
I have a question regarding gravitational waves that I can't figure out. Hope some wise minds here can help a simple amateur without technical or scientific education.
Two black holes rotating around each other generate and emit gravitational waves.…
Peter
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During a total solar eclipse is it possible to see solar flares with the naked eye?
I read that it might be possible but I am wondering can I actually see small flames jetting from the surface around the circumference of the eclipse assuming they are active at the time? There is a total solar eclipse in 2024 that I will be able to…
Sedumjoy
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Why are segmented mirrors lighter than monolithic mirrors?
Everywhere I look, it is recited as a quasi-mantra that "segmented mirrors are much lighter than monolithic mirrors", and I can't manage to find an explanation anywhere no matter how hard I look. To me, getting a monolithic mirror and cutting it up…
David Cian
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Where are Modern Constellation lines defined?
In an astronomy app name SkyPortal you can see the constellation lines as Modern or Traditional lines.
The traditional ones rarely have a resemblance to what they are a symbol of. However, the modern lines make much more sense.
Is there any…
Real Dreams
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What is the mechanism through which mass is converted to thermal energy in the accretion disc of a black hole?
In the book The Cosmic Perspective, it is stated that as matter is falling into a supermassive black hole, up to $40\%$ of its mass are converted to thermal energy, making the accretion of matter around a black hole a vastly more efficient energy…
Vercassivelaunos
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Is the Sun hotter today, in terms of absolute temperature (i.e., NOT total luminosity), than it was in the distant past?
I am constantly reading that the Sun is at least 20% 'hotter', in terms of total radiation/luminosity, than it was a few million years after its formation (i.e., after the Hayashi stage...)
But what about its absolute temperature? I know that it…
Kurt Hikes
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How far apart has the sun drifted from Alpha Centari due to the expansion of the universe since its formation?
From what I read Alpha Centauri formed 250 million years before the sun which was 4.85 billion years. So how far apart were they when the sun formed vs what they are now?
The expansion of the universe must be contributing to it's 4.4 light years.…
Sedumjoy
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Can stars be born giants?
My understanding is that giant stars are formed when they leave the main sequence and begin to burn elements heavier than hydrogen. Can some stars, however, be born as giants or do all stars start off as main sequence dwarfs?
Andykins
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"Tidally locked" Oort Cloud object
Is the Oort cloud spherical enough and are there enough objects in it that it is likely there is at least one in there that it has shown the same face to the sun for billions of years and will continue to do so for billions of years? Just based on…
Rabbi Kaii
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