Questions tagged [orbital-mechanics]

The application of ballistics and celestial mechanics to the practical problems concerning the motion of rockets and other spacecraft.

Filter by
Sorted by
Tagged with
0
votes
1answer
14 views

Orbital mean motion expression derivation

I'm reading an article about tidal forces, and the expression for the mean motion is given by: $$ n = \sqrt{ \frac{G(M + M^*)}{a^3}}$$ Where $G$ is the gravitational constant, $M$ is the mass of the ...
0
votes
1answer
71 views

Why do planets' orbital velocities drop off by less than a third when twice as distant from the sun, rather than three-quarters? If gravity is $1/4$?

Looking at the speeds of the planets in our solar system when traveling around the sun and their distances from it (or, using Kepler's third law,), it seems that when a planets distance is doubled, it'...
2
votes
1answer
35 views

predicting angular seperation between planetary objects and earth satellites

I am struggling to calculate the angular separation between a satellite in earth orbit and a planetary object using the Skyfield library. It's equivalent to calculating the angular separation between ...
21
votes
10answers
6k views

Is the closest planet to another planet always the innermost planet?

In our Solar system Mercury is not only the closest planet to Earth on average but also, for the same reason, the closest planet on average to all other planets (Jupiter, Neptune, etc...). Does that ...
0
votes
1answer
78 views

When will Alpha Centauri A and B overtake Proxima Centauri as the closest stars to us?

There are 3 stars in the Alpha Centauri system: 2 large stars orbting around each other (A & B) and a distant Proxima Centauri (C) orbiting around both. Right now it just happens that Proxima ...
0
votes
1answer
118 views

How to predict future position of body in solar system (without Kepler's equations, N-body problem)?

I have a solar system where each body interacts with each other by force $F = \frac{Gm_1m_2}{R^2}$ Is it possible to predict future position of some random body after t seconds since bodies velocity ...
1
vote
1answer
66 views

If a satelite is in orbit around a two body system what is it's shape?

For example if something was orbiting the sun only slightly further out than the earth, it would risk capture by the earth when the earth caught up to it in it's orbit. If it was orbiting at a great ...
11
votes
5answers
6k views

If a satellite is put into the same orbit of the Sun as Earth, how does it avoid hitting Earth?

If a spacecraft follows literally the exact orbit of Earth at a different speed to Earth then why doesn't it hit Earth at some point? I'm specifically thinking about this in relation to these ...
2
votes
1answer
154 views

Where can I build my house on Mercury so that I can see double sunsets (and sunrises)? Can I do it near the poles where it's cooler?

CNN'S Mercury mission flies by closest planet to the sun for the first time says at the end: Mercury's unusual rotation and oval-shaped orbit around the sun (sic) means our star seems to quickly rise,...
1
vote
1answer
75 views

Could the Moon placed near the Sun-Earth L1 point remain in a heliocentric 1:1 resonant orbit with Earth? If Earth were at 1 AU, where's the Moon?

This answer to How much mass can be put in an L4 or L5 and it still maintain reasonable stability? has left me with the gedankenexperiment of the Earth in a circular orbit around the Sun, and the Moon ...
2
votes
0answers
51 views

How to calculate orbital velocity of binary star?

I am trying to simulate the Alpha Centauri AB System. I built the simulation, it works flawlessly when trying to simulate our solar system, and I am now trying to simulate the AB System. I found all ...
3
votes
2answers
113 views

Why doesn't Triton orbit over Neptune's equator?

In this answer, I wrote (on another account) why most moons orbit over their planet's equator. Any rotating planet has an equatorial bulge that shifts its moons' orbits around its equator over long ...
5
votes
1answer
433 views

Confused on how you are supposed to calculate eccentricity without apsides

I'm kinda confused on how to calculate either the apsides or the eccentricity without knowing one or the other. Let's say you have an object in orbit around another. If you know the current distance, ...
1
vote
1answer
148 views

What is the maximum speed in which a human jumping away from Deimos and towards Mars would actually fall back down rather than enter Mars' gravity?

Imagine a universe in which Deimos and a human are the only objects in the universe. It doesn't matter if the human jumped even 1 nanometer per second slower than escape velocity, they would still ...
1
vote
0answers
33 views

How to translate from local laplace plane to ecliptic J2000 (or ICRF)

The NASA JPL websize gives mean orbital elements for e.g. Iapetus or Titan in relation to the local laplace plane. ...
3
votes
0answers
74 views

Orbiting around a common barycenter in Kurzgesagt video: "The Largest Black Hole in the Universe"

Observation This video by In a Nutshell visualises the V723 Mon orbiting a smaller and heavier object/black hole named Unicorn. However, the animation shows Unicorn and V723 both orbiting some common ...
3
votes
1answer
75 views

Where can I find planetary rotational axis direction?

I can find axial tilt of planets easily, but that doesn't specify the direction of that tilt, i.e. planet's rotation axis may be anywhere in circle defined on a sphere by axial tilt value. And I can't ...
4
votes
1answer
69 views

What are typical peculiar velocities?

I'm wondering what sorts actual values we can expect to find for peculiar velocities of individual objects when observing the universe, both typically and on the high end. I'm interested in any ...
2
votes
0answers
39 views

What's the formula for change in argument of periapsis over time due to J2 perturbations for a geocentric satellite?

I'm trying to propagate the orbit of the ISS, but it became very clear to me very quickly that the J2 perturbations were nothing to scoff at. A quick google search gave me the equation for the change ...
4
votes
0answers
36 views

Is there a certain thermal inertia for maximum Yarkovsky?

The video below summarizes current work at asteroid 101955 Bennu by OSIRIS-REx to characterize its properties to provide better estimates of the Yarkovsky effect1's impact on its trajectory for an ...
1
vote
3answers
175 views

Why doesn't the Moon fall out of orbit?

If you need to boost ISS to stay in orbit why moon doesn't fall down to earth and KABOOM?
5
votes
2answers
160 views

How to calculate eclipses on a planet in a binary star system

I posted this question on the physics page but decided it might be best if I post it here instead as it may be a more astronomy related question. I also haven't received any answers over there so far ...
3
votes
0answers
38 views

Is there software that will let me calculate things like lunar phases and the position of bodies in the sky in a custom solar system?

I am constructing a fictional solar system and want to be able to calculate astronomical events and locations, like lunar phases and eclipses, plus the positions of other astronomical bodies in the ...
1
vote
1answer
100 views

In which town is the length of the day bigger on 23 of September?

I'm trying to solve this task: Moscow and Kazan are located on the same parallel. In which of them the length of the day is bigger on 23 of September? In Kazan the sun will rise earlier, because it'...
1
vote
0answers
26 views

Virgin Galactic's and Blue Origin's Space Flights - are these just Extended Skydiving in an Enclosure? [closed]

Sorry for three questions in the three paragraphs below, but they all are around the same curiosity that I have. In both of Virgin Galactic and Blue Origin's space flights happening in July 2021, it ...
4
votes
1answer
131 views

Confusion when calculating the length of the day

I'm trying to solve this task: Tula and Moscow are located on the same meridian. In which city length of the day is bigger on 22 of June? 22 of December? I was thinking like that: we need to ...
2
votes
1answer
70 views

relation between angular velocity of planet and orbital velocity [closed]

Can it be shown that angular velocity of a planet = (orbital velocity/h+Radius): $$\frac{v_{c,1}}{h + R_{⊕}} = \omega_e $$
3
votes
1answer
124 views

Mars is getting closer to Earth through its elliptical orbit becoming more eccentric. Do Earth and Mars keep getting closer? [closed]

A NASA Mars article says: Mars' orbit is more elliptical than Earth's, so the difference between perihelion and aphelion is greater. Over the past centuries, Mars' orbit has been getting more and ...
1
vote
0answers
50 views

Virial theorem for a binary system

I am trying to derive the virial theorem but for two stars orbiting each other. I know the derivation for the general virial theorem with i particles but I am wondering if there is a quicker or more ...
7
votes
1answer
301 views

Degrees of freedom in restricted circular coplanar three body problem

How many degrees of freedom does a mechanical system consisting of three bodies, the Sun, Jupiter and an asteroid, have in the restricted circular coplanar problem of the three bodies? I know that if ...
3
votes
2answers
108 views

Can we learn anything from the chaotic movement of Hydra and Nix?

The NASA Visualization Explorer Moons In Chaos says Hydra and Nix, two of the moons of Pluto, show chaotic movement due to the shifting gravitational field. How long a day lasts and where the sun ...
1
vote
0answers
71 views

Orbital resonance 2:1

I considered the motion of an asteroid around the sun, in a $2:1$ orbital resonance with Jupiter. Following the study of this resonance, it was observed that the angle between the major axis of the ...
3
votes
1answer
162 views

Can Stellar Spaghetti ever escape?

Spaghettification is the deformation of a body into long, thin strips due to tidal forces as the body passes through a powerful gravitational field. Image from wikipedia: Stellar spaghetti has been ...
2
votes
0answers
71 views

When an object revolves around an oblate planet, in near-circular orbit, does the oblateness ALWAYS make it moves FASTER?

tl;dr: The orbital period for a Keplerian orbit of a small body around a massive one with standard gravitational parameter $\mu=GM$ and semi-major axis $a$ is given by $$T = 2\pi\sqrt{\frac{a^3}{\mu}}....
0
votes
1answer
164 views

Trajectory: What would happen if the sun disappeared one day?

So, let's just assume, to no aspect explainable to humans, the sun just magically popped out of existence on January 1st next year (2022), that'll never happen, this is just a scenario to explain my ...
-1
votes
1answer
60 views

Non-keplerian orbit features

For the first Kepler's law the orbit of a planet is an ellipse, with the Sun in one of the foci, but I've read that in the case of an homogeneous sphere distribution, orbits can be elliptic, but the ...
0
votes
0answers
54 views

Orbital Angular Momentum of a Binary Star System

Let's say you have a binary star system, consider the orbital motion of that binary star consisting of two solar-like stars separated by 20 stellar radii. How would one calculate the angular momentum ...
3
votes
2answers
71 views

Nodal Precession of Planets

It is obvious that the longitude of ascending node ($ \Omega $) of a planet gradually changes with time. For example, the VSOP planetary theory accounts for this. In Astronomical Algorithms (Meeus ...
4
votes
1answer
91 views

Where can I find a list of retrograde Milky Way stars?

I read in papers that the Milky Way contains some retrograde stars (retrograde to the Milky Way rotation). Does anybody know where I can find a list of them, possibly including data on their distance ...
1
vote
0answers
36 views

What is the period of the 'cycle' of Earth's ecliptic variation, relative to the 'invariable plane'? 70,000 or 100,000 years?

The plane of Earth's path around the Sun, the ecliptic, is different from the average of the solar system's as a whole (the invariable plane) by about 1.57°.... Our path around the Sun, though, goes ...
4
votes
2answers
144 views

Orbital path projections onto a 2D plane

In ProfRob's excellent answer to Is S2 still the fastest known star in the galaxy?, he posted a figure of the orbital paths of stars passing close to the supermassive black hole near the center of the ...
3
votes
1answer
126 views

Could photons orbit a black hole if fired at the correct angle?

My experience with Kerbal Space Program gives me the impression that it's impossible to transfer from a stable orbit of one body to the stable orbit of another without deceleration. But is this true ...
18
votes
2answers
2k views

Is S2 still the fastest known star in the galaxy?

Wikipedia's entry for the star S2 says that it has the fastest known ballistic orbit, reaching speeds exceeding 5,000 km/s (11,000,000 mph, or ​1⁄60 the speed of light) and acceleration of about 1.5 ...
11
votes
2answers
1k views

What is the longest natural bound orbit chain observed?

Define a bound orbit chain as a list of successively less massive bodies, each in a bound orbit with the bodies preceding it in the list. Then an example of a bound orbit chain would be: <Sun, ...
2
votes
0answers
61 views

Why do the asteroids orbit the Sun in roughly the same plane as the planets?

The asteroid belt between Mars and Jupiter is an extremely active environment (on an astronomical time scale) where collisions between 10km radius bodies occur every $10^7$ years, according to ...
1
vote
1answer
58 views

Moons within a Gas Giant

Assuming a gas giant is primarily gaseous past our visibility, is it possible that a moon traveling at a sufficient velocity would be able to exist within the atmosphere, or would terminal velocity ...
2
votes
1answer
50 views

How can I find the width of an orbit knowing some values?

I need to find the width/x-radius of an orbit, which is ellipse shaped, knowing variables like the orbit's length(perihelion + aphelion in this case) and the eccentricity. I am not sure if this is ...
2
votes
2answers
96 views

Could our Sun be the product of an ancient stellar collision?

The canonical model for the formation of the Solar System involves the gravitational collapse of a nebula into (perhaps) several stars across several light years. Is it possible that two or more of ...
4
votes
3answers
727 views

Computing the rate of orbital decay

We know that the estimated time until a binary system merges is given by: $$\dfrac{5c^5r^4}{256G^3(m_1m_2)(m_1+m_2)}$$ But what is the formula to determine rate of decay, in some sort of distance unit,...
5
votes
2answers
301 views

What is the thickness of the Solar System disk?

What is the thickness in AU of the all planets' orbital plane height combined in the Solar System? Excluding Pluto. Looking for h

1
2 3 4 5 6