Unanswered Questions
704 questions with no upvoted or accepted answers
19
votes
0answers
760 views
Terrestrial Exoplanet Skies – I've Built a Visual Sky Chart. Is it Accurate?
I'm an artist (and science enthusiast) and I've been trying to find a comprehensive resource that would help me clearly identify likely sky colors (as perceived by human vision) for exoplanets that ...
11
votes
0answers
132 views
The recent results on Hubble constant measurements
In recent news there is this announcement
In the introduction they say:
Distance measurement discrepancy: a $4.4σ$ tension on the value of $H_0$
and I understand the discrepancy is with the ...
11
votes
0answers
239 views
Is Optical VLBI theoretically feasible? If not why not?
There are plenty of optical interferometers in use with baselines of up to maybe 1km. As far as I can find out, they all work by directly collecting the light at all the telescopes, using mirrors to ...
10
votes
1answer
145 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
votes
0answers
259 views
How would astronomical seeing on Mars differ from that on Earth?
Astronomical seeing is the limiting factor for the resolution of all but the smallest Earthbound telescopes.
Source
Stunning advances in adaptive optics (along with it's predecessor speckle ...
9
votes
0answers
112 views
How would the sky look if Earth orbited a red giant at a safe distance?
Let's say that instead of the sun, we have a red giant, but are orbiting it at a safe distance, within the goldilocks zone. Would the sky actually look more red? Or would it be closer to white/...
9
votes
0answers
464 views
How to determine scalar-to-tensor ratio r from CMB polarization spectrum?
CMB polarization spectrum can tell us about the primordial scalar and tensor perturbation. By analyze B and E mode angular spectrum power spectrum and temperature power spectrum we can determine the ...
8
votes
0answers
147 views
What do the fusing 'onion layers' of a pre-supernova star look like to scale?
I'm sure we've all seen the diagrams of various layers of element fusion from hydrogen to silicon in a star that's just about to go supernova.
(Picture from courses.lumenlearning.com)
I suspect ...
8
votes
0answers
87 views
How actively is Deep Learning being used in exoplanet identification?
Papers, like this one from Google, show that Deep Learning and Machine Learning are effective in detecting exoplanets from luminosity data provided by telescopes like TESS or Kepler.
These models ...
8
votes
0answers
94 views
How does the gravitation of Jupiter or other big planets affect Kepler's third law?
Does anyone know any good reference on this?
I remember reading once about how Jupiter's gravitation can be treated as a perturbation, but I cannot find it again now. I think they expanded Jupiter's ...
8
votes
0answers
212 views
What are Kepler's laws (as he wrote them)?
There are of course many, many sources that quote Kepler's laws of planetary motion. This is preventing me from finding out what I really want to know: which is - what are Kepler's laws as he wrote ...
8
votes
0answers
194 views
Planning to revisit Arthur Eddington's experiment from 1919
As the fateful day draws closer, the United States will host a celestial event that comes once in three generations. I plan to witness this first hand at the exact center of greatest eclipse.
In the ...
8
votes
0answers
103 views
Estimating the tangential and cross component of the galaxy's shear using Gnomonic projection
I would like to know how I can estimate the tangential and cross component of the galaxy's shear using Gnomonic projection of the right ascension and declination ...
7
votes
1answer
181 views
First observation that the Sun and Jupiter (and friends) move around a common barycenter?
Answers to the question How did Kepler determine the orbital period of Mars? describing careful observations centuries ago got me thinking.
What was the first analysis of observations that directly ...
7
votes
0answers
204 views
What fraction of a star's hydrogen store will be fused over its lifespan?
A main sequence star will fuse some of its hydrogen, but not all. In massive stars ($>1.5M_\odot$) the core is convective but the rest of the atmosphere radiative and hence does not mix much: as it ...
