Questions tagged [orbit]

Questions regarding an object 'falling around' another object, due to a combination of gravity and momentum.

53 questions with no upvoted or accepted answers
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1answer
176 views

Error propagation methods for orbit parameters

Recently I've encountered an article in our local astronomical popularization magazine. It is about a well known task of Sgr A*-black hole's mass estimation. The article is written as a step by step ...
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131 views

Semimajor axis variations in co-orbital moons

I've been playing with simulations of co-orbital bodies similar to Saturn's moons Janus & Epimetheus- horseshoe orbits where the two bodies are of comparable mass- and I'm seeing some very odd ...
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Kepler - Creating the Ellipse (Astronomia Nova)

In Chapter 58 in Astronomia Nova, Kepler made his final step to finally create the ellipse (for the orbit of planets) http://science.larouchepac.com/kepler/newastronomy/part4/58/index.html In the ...
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1answer
50 views

Orbital terminology for satellites relative to one another

Basic question, but I'm trying to describe a planetary system and coming up short on vocabulary. Do either of the following exist?: A word for the closest pass between two satellites orbiting the ...
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89 views

Gravitational Slingshot

If a spacecraft slingshots around a planet P (with escape velocity V) at an angle $\theta$, I understand that the resulting velocity is $${ v }_{ 2 }=({ v }_{ 1 }+2u)\sqrt { 1-\frac { 4u{ v }_{ 1 }(1-...
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85 views

What was "wrong" about the motion of Neptune in 1984?

The cover story of the March 1984 issue of RUN, a popular computing magazine, was written by noted astronomer Charles T. Kowal. In the article, he describes how he uses his home computer, a Commodore ...
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74 views

What maintains the high orbital eccentricity of many exo-planets near their sun?

Over the last decade we've discovered that many exoplanets not only have highly eccentric orbits, but also orbit very close to their sun. This is true of many classes of stars. I definitely have a ...
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42 views

Aaditya L1 mission ISRO

ISRO's next mission to the Sun is Aditya-L1, (also here), which will be placed at the Sun-Earth Lagrangian point L-1. Why it is not placed near L-4 or L-5, since these are stable equilibrium point ...
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112 views

Average effect of a planet on a comet

I'm considering a problem involving star S, planet A, and a comet B. The orbits of the planet and comet are eccentric, with eccentricities $e_A$ and $e_B$. I'm trying to calculate the average change ...
3
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58 views

Linear motion in the equatorial frame

I would like to calculate how the RA/Dec changes when an object has an apparent linear motionin the equatorial sphere. For example, more or less what an artificial satellite would do in a circular ...
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30 views

Why are triple conjunctions in a resonance forbidden?

I was reading the Wikipedia article about orbital resonance and noticed that Laplace resonances forbid triple conjunctions. This seems to be supported by the Io-Europa-Ganymede system and the Nyx-Styx-...
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47 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 ...
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74 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 ...
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81 views

Planets orbit fitting

I would like to fit planets orbits. To do this, I need a set of mock observations. I can get them from right ascension/declination obtained from the Horizons interface: EDIT: Horizons gives me a list ...
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35 views

Classical Mechanics : Interaction Sun Radiation Pressure - Gravitation

I have a theoretical problem that merges the effects of a gravitational field and the Sun radiation pressure. The problem goes as follows: A spacecraft orbits the Sun in absence of any other body ...
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73 views

Moon's and nodes' inclination to the Invariable plane

Moon is inclined to the ecliptic 5.14 degrees. Earth's inclination to the invariable plane is 1.57869 degrees. What is the Moon's, and node's inclination to the invariable plane? Since the Moon has an ...
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48 views

What should be the "poles" for irregular shaped bodies?

Continuation of: What is the definition of a "pole" of a celestial body? From uhoh's answer, we can conclude that a distinct bodies should have a center of mass. If the body is spherical, ...
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52 views

How is solar radiation pressure included in the SGP4 orbital propagator?

TLE sets serve as input elements for the SGP4 orbital propagator. Several orbital perturbation effects are considered in the SGP4. However, it is not obvious to me how (or if) the solar radiation ...
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51 views

How to write a normalized, dimensionless form of Binet's relativistic equation?

$$\frac{\delta^2 u}{\delta \theta^2} + u = \frac{\mu}{h^2} + 3 \mu u^2$$ This is Binet's relativistic equation. Here $u = 1/r$ where $r$ is the radial distance, and $\mu$ is the reduced mass of the ...
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105 views

Orbital decay of the Earth's orbit and Earth's moving closer to the Sun

If we consider orbital decay of the Earth's orbit, then can we counter argue with the following reasons? Due to tidal effects transferring small amounts of angular momentum from the Sun's spin to ...
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55 views

Are circumbinary and noncircumbinary habitable zones mutually exclusive?

Could a binary star system have an earth-like planet orbiting star A, a second earth-like planet orbiting star B, AND a third earth-like planet in a stable circumbinary orbit? Or does the space that ...
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162 views

Modeling planet rotations (time of day, obliqueness, etc.)

I created this solar system model using POV-Ray: by following these instructions: https://ssd.jpl.nasa.gov/txt/aprx_pos_planets.pdf The next thing I want to do is orient/rotate each globe correctly ...
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87 views

Weird 2 body swapping orbit

While messing around in https://dan-ball.jp/en/javagame/planet/. I came across a pretty stable orbit of 2 bodies around a star Orbit yellow: Orbit Blue: full album: https://imgur.com/a/ruyenmY Is ...
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52 views

Is there a computer simulation that anyone knows of that describes the loss of a moon as it's orbit extends beyond the Hill Sphere of the planet?

Let's imagine a moon orbiting a planet at 75000km distance (assume circular orbit). Now let's say that the Hill Sphere of this planet only extends to 78,000km (small planet in the habitable zone of a ...
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233 views

Shared moon in a double planet system

Would it be possible for two planets orbiting around each other to share a moon that orbits both separately? Would the moon in question would do something akin to a large figure 8 as it orbited both ...
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215 views

If a large satellite keeps a planet from wobbling,why is Pluto/Charon on its side?

I understand that a “large” moon, like ours, keeps the planet’s axis from being peturbed, because the spin axis and the moon’s orbital plane exchange momentum and tend to stay in the same plane, and ...
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50 views

How to calculate the new orbit after a instantaneous change in a well defined initial one?

Say one has a simple two body system (and one body is much more massive than the other, for example a star, planet system) where all the quantities about it are know, that is the eccentricity, masses, ...
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81 views

Singularity in Laplace Method for Orbit Determination

I have a question about Laplace angle-only method for orbit determination where the line of sight vectors are being interpolated. I read somewhere that the method fails (due to a matrix being singular)...
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1answer
151 views

How to lose the moon?

In this worldbuilding question, the moon is gone: an extra-solar gas giant passed close by Earth in which the Moon was knocked from orbit to become a planet in an independent orbit, as well as ...
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48 views

What is the skypath of JWST?

JWST will be in a 6 month halo orbit around the Sun/Earth L2 point, which is located at the anti-solar point. Internet graphics give conflicting information on whether the skypath is clockwise or ...
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29 views

Average DeltaV applied to a comet during outgassing?

Comets' orbits often change during perihelion passage due to the outgassing of volatiles. So I am wondering, how much change in velocity is applied each perihelion pass? What does this depend on?
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Is there a formula for a planet's orbit in a 3D space?

I'm trying to model the orbits of Earth and Mars and their positions at a given point in time. But I can only find 2D equations of elliptic orbits, which only contain the x and y variables. I have to ...
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83 views

Calculating Angle Between Two Planets In Heliocentric Orbit

My goal is to calculate the retrograde of Mercury. What I've been working from is the book, Practical Astronomy With Your Calculator 3rd edition. I've made some progress, but I seem to be stuck with ...
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37 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 ...
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48 views

Visual binary star with circular apparent orbit

Does anyone know a good example of visual (or interferometric) binary star apparent orbit of which looks circular due to projection though in fact is markedly elliptical? I need that for teaching.
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80 views

Do the orbits of planets change? Where is the data for this?

Everything in the space is moving all the time. Do the orbit of major Solar Systems planets, Mercury to Saturn change? Just like Moon's orbit around Earth changes. How often, how small or big is the ...
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36 views

Sun's and planets' inclination to the Invariable plane

What are the inclinations of all major Solar system planets (Mercury to Pluto) to the invariable plane? Looking for accurate data calculated on them. Also, What is the inclination of the Sun to the ...
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50 views

Positions of planets before Christ?

All the solar system simulations I've come across showing the positions of planets only show the positions in a certain time period, at beginning of the first millenium the earliest. There was just ...
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Orbital Mechanics: where can I find initial conditions for orientations and angular rates of planets in our solar system?

I am looking to write the equations of motion (EOMs) for a 6DOF analysis of our solar system. I want to integrate the equations forward in time, and need a complete set of initial conditions to do so....
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202 views

Which spacecraft would be moving faster?

If identical spacecraft were orbiting Mars and Earth at identical radii (distances), which spacecraft would be moving faster? Why? My reasoning is based on equation: a3 = P2 * (M1 + M2). Earth's mass ...
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Where and when will someone on Earth be standing with the floor parallel to the Ecliptic plane?

I have been trying to figure this out and I think the answer might be - once per day for anyone living on the Tropic of Cancer or Capricorn. Is that right? To be clear - I want to know where on Earth ...
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Orbitally convenient Mars-to-Earth transit times?

Are there any peculiar solar system layouts that would result in highly efficient transits between Mars-to-Earth? I am aware of a Hohmann transfer orbit, but can other planets be used to "sling-shot" ...
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264 views

Orbits of planets in ecliptic coordinates

Is it possible to get the ecliptic coordinates of orbits of planets for a specific date and time? Does the ephemeris data of planets help in constructing that? Any help on this would be helpful. I ...
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374 views

To show perihelion precession motion of Mercury in Python with matplotlib

I'm trying to make it more general code so I can trace even a parabola or hyperbola for $e=1, E=0$ and $e>1, E>0$ respectively. And after achieving that general code I want to make the same code ...
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How much does being at the perihelion heat Earth up?

The author in this article: https://news.nationalgeographic.com/news/2010/07/100707-aphelion-heat-wave-earth-sun-science-weather-nation/ has explained that positional differences on the orbit is a ...
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111 views

How to convert a function of keplerian elements to a function of equinoctial elements?

I need to convert the Keplerian orbital elements to the equinoctial elements and then use the converted elements"equinoctial" in the function "d" below. To do this, first, I converted the Keplerian ...
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1answer
81 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 ...
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How often does the configuration of the Trappist-1 system repeat

My question is simply how long it takes for the 7 known planets in Trappist-1 to be in the same configuration in relation to their host star, and to each-other. Those seven planets are in a 2:3:4:6:9:...
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44 views

2-body orbits expanding in nbody simulation?

Recently, I designed an n-body engine and tested it with a binary star system. After a minute of running, the orbit began noticeably expanding: Why is it happening, and is this natural? The source ...
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59 views

Wrong planet orbit

I would like to calculate Mercury's orbit in Mathematica. My initial conditions, in AU and AU/year, are: ...