Unanswered Questions

7
votes
0answers
116 views

Why are retrograde orbits more stable than prograde ones?

Regarding solar system dynamics, i.e. planets in stellar systems and moons in planetary systems, this is often mentioned in the literature, but it is difficult to find a good analysis/explanation of ...
6
votes
1answer
259 views

How can one explain the apparent motion of the Sun from a heliocentric point of view?

From a horizontal frame of reference, the path of the Sun looks like a part of a circle in a tilted plane, as shown in this picture: ...
6
votes
2answers
94 views

Does the shape of a supernova remnant depend on the progenitor star's magnetic field?

The magnetic field activity in a star can be very chaotic and my question is are they somehow related?
6
votes
0answers
121 views

Method to determine the amount of reflected starlight necessary for an exoplanet to be visible from a given distance/angle?

What is the method to determine the amount of reflected starlight necessary for an exoplanet to be visible from a given distance/angle? (Not from occlusion but actually visible on its own.) Further, ...
6
votes
0answers
51 views

What implications does younger volcanism have on the Moon's thermal evolution?

In the paper Evidence for basaltic volcanism on the Moon within the past 100 million years (Braden et al. 2014), suggest that features such as Ina (image below) represent a far more recent age of ...
6
votes
0answers
135 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 ...
5
votes
0answers
61 views

What is the frequency distribution for luminosity classes in the Milky Way Galaxy?

I'm working on a game concept that does some mild simulation of realistic stellar classes and luminosities. In particular, I'd like to roughly model the general frequencies of the classes and ...
5
votes
3answers
201 views

Is extraterrestrial mining more difficult or impractical for bodies without plate tectonics?

This article talks about the possibility of mining Uranium on the moon. Since the Moon lacks the geological forces that have created veins of concentrated minerals on Earth, would extraterrestrial ...
5
votes
2answers
99 views

Was that actually a shooting star during the supermoon eclipse on September 27th 2015?

During the super-moon total lunar eclipse on September 27th a meteor-like streak passed very close within view of the event. It appeared to happen at the very middle, the maximum eclipse. ...
5
votes
0answers
56 views

The battle over Gliese 581 and Gliese 667C?

In 2014, Robertson et.al. made a case that stellar activity is masquerading as planets (here and here) for these well known systems. In both cases, they claim that the only real planets discovered so ...
5
votes
3answers
128 views

How/where to check where the Sun is (constellation)?

I would like to check in which constellation the Sun was in at some time in the past, any recommendations how to do that?
5
votes
0answers
114 views

How to calculate geocentric conjunction time and moon altitude at a given time

Umm al-Qura calendar of Saudi Arabia determine the new moon if these criteria meet at 29th day: The geocentric conjunction occurs before sunset. The moon sets after the sun. I've got the formula ...
5
votes
0answers
47 views

What is the cause of the variation from high and low mean obliquity periods of Mars?

It is reasonably well known that Mars has a greater obliquity range than Earth, due to Mars lacking a stabilising influence of a large moon. However, the Martian obliquity seems to have gone through ...
5
votes
0answers
127 views

Python 2D Jean Instability in Spiral Galaxy Simulation

I have ~1000 snapshots of a spiral galaxy simulation (from Molecular cloud perturbations t=0 to t>1Gyr. What I need to do is determine whether any position at any of the snapshot times meets criteria ...
5
votes
0answers
94 views

Sedna, VP113 and the likelihood of the PX/Tyche/Thelistos hypotheses

Crosslisted question from http://physics.stackexchange.com/questions/131876/sedna-vp113-and-the-likelihood-of-the-px-tyche-thelistos-hypotheses The recent discoveries in exoplanetary science ...

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