Questions tagged [orbit]

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

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1answer
58 views

What is the exact time of sun stay in each zodiac every year on sidereal year duration?

I tried to reverse engineer from astro-chart times at which sun stays in a zodiac. Here is the list. ...
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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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Does the orbits of stars in a binary system have a common focus, which is the center of mass of the stars?

I know that when a planet orbits a star (and assume the star is stationary because its mass is >> the mass of the planet), the orbit is an ellipse, and the star sits at one of the foci of the ellipse. ...
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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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1answer
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What's the difference between semi-major axis and apoapsis?

The semi-major axis is half of the diameter of the major axis of an ellipse by definition. So how does that make it any different from apoapsis, the furthest point an object is from a parent body in ...
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1answer
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Can Kepler's 3rd Law be applied in higher dimensions to describe orbits (quadric surfaces)?

Motivation for asking: The 2-D orbital path of a celestial body revolving around another celestial body due to the force of gravity can be described by a conic section; this is the curve formed by ...
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3answers
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How long is the Sun closer to Earth then Mars is?

A recent question at Space.se has generated a few comments that are interesting. But the answer to one particular comment to might address a lot of misconceptions. I imagine the actual halfway ...
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1answer
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Sun and moon's orbit in ecliptic coordinates using skyfield

I am new to using skyfield, is there any doc or help file that can show me on how to get the orbit of Sun and moon in ecliptic coordinate for a particular date and ...
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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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1answer
54 views

Calculating object velocity at perihelion

I would like to calculate the velocity of an asteroid orbiting around a star (Sun) at the perihelion of its orbit. I know the excentricity of the ellipse and its semimajor axis. I have found that the ...
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Is Earth's Surface “In orbit”?

I'm having trouble understanding relative angular/tangential speeds at increasing altitudes above Earth's surface. In particular, I find this comparison of tangential velocities on Wikipedia very ...
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How to determine the orbital period of an asteroid using Kepler laws given its orbit's radius?

Given that the mean distance of an asteroid from the Sun is $450 \times 10^6$ km is it possible that the asteroid completes one rotation around the Sun in two years? According to the third law of ...
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Why are there so many binary systems?

Most star systems are binary, but why is that? Why would new stars form close to others, and not (relatively) evenly spread? And even if they are clustered close together, why are the majority binary? ...
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Beneficial astronomical uses of satellite constellations like Starlink?

Has any thought been given to software that would use predictable occultations by Earth-orbiting satellites to improve (rather than degrade) astronomical observations? Potential challenges I could ...
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1answer
341 views

Troop of moving stars through a straight line [duplicate]

Last night,I and my brother suddenly saw that some(50-60) dots of light( exactly like stars) were moving through a straight line(from NW to SE) above us with same velocity and towards exactly same ...
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1answer
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How to find the Orbital Period of two Binary Planets around a Single Star?

This is kind of a weird one. Bare with me! :) Background: (Skip to the math below if you just want to answer questions) In my favorite game, Elite: Dangerous, I "own", or occupy I guess, a system ...
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188 views

Could a star closely orbit a black hole long enough for the star to have lost 0.5B+ years to time dilation?

I was wondering how stable a close star-black hole system could plausibly be, and thus how much time a star could plausibly miss out on (from an outside observer's perspective) due to being in an ...
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Rocket Equation from Newton’s 3rd Law, Force of Gravitation, and dp/dt [closed]

I am using the derivative of momentum (dp/dt) with Newton’s 3rd Law with the gravitational force of Earth.   $$ F - F_{gravity} = \dfrac{\mathrm{d}p}{\mathrm{d}t} \\ F - \dfrac{G \, m_e \, m_r}{...
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Find x,y,z velocity component of a star? [closed]

I am trying to find the initial x,y,z velocity components of the Epsilon Lyrae stars. How might I go about doing this? The radial velocities are available on Wikipedia, but I am not sure how to use ...
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1answer
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Orbital speed is (vector) sum of tangential and normal speed?

Orbital speed definition in wiki does not state clearly - it is just tangential speed component or square root of squares of normal and tangential speed (full speed vector). When we say that moon ...
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2answers
134 views

Can we calculate the orbit of exoplanets?

I'm not an astronomer, but the question came up and I'm interested if we are able (or how accurate we are able) to calculate the orbital parameters of an exoplanet. Since the transit method must yield ...
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Night-Day Cycles in S-Type Planetary Systems

I am a writer and space enthusiast. For a story I am currently writing I would like to have a planet which orbits a star which resembles the sun, which in turn orbits another star. In this situation ...
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1answer
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Visitors that became satellites?

To anyone's knowledge, has there ever been an object that approached the earth and was captured into an orbit? Is it thought that there might be such objects simply too small to spot or just not ...
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1answer
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Would two Earth-like planets on opposite sides of a Sol-like star at about 1 AU be a stable configuration?

Would two Earth-like planets on opposite sides of a Sol-like star at about 1 AU be a relatively stable configuration? I understand that there are tadpole-like orbits and the two planets may not stay ...
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1answer
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By convention, when observing an exoplanet, is the observer's line of sight (on Earth) perpendicular to the plane of sky?

This is just a quick question. In this picture of the orbit of an exoplanet, is the observer's line of sight perpendicular to the plane of reference, which is in the +z direction on the diagram? In ...
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Are there any planets or objects orbiting in Goldilocks zone?

I was wondering whether there were any objects that orbit the "goldilocks zone" besides our home planet earth, and how the goldilocks zone of our solar system is defined.
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Can a system of three stars exist?

Just like binary stars can a system of three stars mutually equidistant from each other? What I mean is three stars at the vertices of a equilateral If yes than what will be the orbit of a planet out ...
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1answer
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How Long Will Earth's Year be When Our Sun Goes Red?

We live in a planet that orbits 93 million miles from a G-type main-sequence star, or "yellow dwarf". That is far enough for a revolution of 365 days. Such is the case of Kepler's Third Law of ...
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What is wrong with this measurement of the synodic period of Mercury?

I'm measuring the synodic period of Mercury using Stellarium. When measuring the synodic period one needs to choose a reference point to start the measurement, and I choose the point when Mercury is ...
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How do you call it when two celestial bodies come as close to each other as they will in their current orbits?

On Earth, we say Mars is in opposition when it is 180º from the Sun, which also marks the times when Mars and Earth come closest to each other. Is there a specific name for such proximity events? For ...
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Why do transits of Earth across the Sun seen from Mars follow a pattern of occurring after 26, 79 then 100 years?

According to this answer transits of Earth across the disk of the Sun as seen from Mars: The (Arthur C.) Clarke story is quite correct. Earth (and Moon) would transit the sun from the viewpoint of ...
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View of other planets from the Earth

There appears to be varying positions/spots of view of other planets from Earth, if I'm not wrong. Now, given that all planets are on the same plane, why do their positions change on the night sky for ...
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If the Moon were impacted by a suitably sized meteor, how long would it take to impact the Earth?

An answer to the question of How well would the Moon protect the Earth from a Meteor? mentions as a possibility that the Moon could get knocked into the Earth. What is the smallest change to the ...
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When was it realised that most major moons orbit in the equatorial plane of their parent planets?

Inspired by the discussion of the moons of Uranus providing a clue to the planet's axis of rotation in this question, I'm wondering when it was realised that the major satellites are typically located ...
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Why does matter spiral into blackholes?

Narrators of astrophysics documentaries constantly state that matter spirals into black holes as if it were intuitive that this would happen because of gravity. But the moon isn't spiralling into the ...
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1answer
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Lunar eclipse above the atmosphere

Would a lunar eclipse seen from low (or even high) Earth orbit look different to the naked eye than it does from the surface of the Earth? The only image I could find taken from orbit was the photo ...
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1answer
68 views

Earth's perihelion vs winter solstice [duplicate]

I found that Earth's perihelion occurs roughly two weeks after winter solstice similar thing happens for summer solstice and aphelion. I understand what those terms mean but I don't understand the ...
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2answers
3k views

Why does the Earth have a z-component at the start of the J2000 epoch?

When I go to the NASA HORIZONS webpage https://ssd.jpl.nasa.gov/horizons.cgi and ask for the VECTOR coordinates of the Earth on 1 January 2000, it tells me that Earth has the following coordinates ...
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I need help with an equation for figuring out the surface temperature of Red Dwarf!

Say you have a 10 billion year old, slow rotating, quiescent M5 star with a mass of 0.32 M☉ , a luminosity of 0.018 L☉ and a burning (haha) desire to figure out the surface temperature. However you ...
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What effect does Earth losing a part of its mass have, is there an impact on the Earth's orbit around the Sun?

This is a random question that popped into my mind. I'm not a physicist or astronomist, however, I am genuinely curious. Also, this is not intended as a science fiction question, but an actual science ...
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Does the Milky Way orbit around anything?

We know most of the objects in the Universe have a spherical or elliptical shape. The object which has less mass and gravitational pull orbits around the nearest object with more mass and ...
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1answer
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Aphelion and the solstice

We have just passed one of the solstices and are approaching aphelion. The two events are close but not simultaneous. There is no very obvious (to me) reason why the two should coincide or be close. ...
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What would change if Venus rotated at a speed and direction similar to Earth?

I am interested in two aspects of this question. Imagine that Venus had a similar rotation speed and the same direction of rotation that we have here on Earth. What would change for Venus itself? I'm ...
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Has the effect of other planets on Earth's orbit been ever measured?

Since other planets have their own gravitational pull, I'm wondering if their effect on Earth's orbit has ever been measured? I know that in comparison with the Sun's pull the effect might be rather ...
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Small orbital body detection [closed]

What technology is required to detect a coconut-sized sphere in Earth orbit, at average altitude of communications satellites?
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1answer
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How can the oblateness of Earth impart torque to change the longitude of ascending node of a satellite?

I've read that you can change the longitude of ascending node of a satellite (i.e. changing the orbital plane without changing the inclination) to change its orbital plane by using the torque imparted ...
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Why is true and average anomaly of planet important?

Why is a true and average anomaly of the planet important? What useful information do they give us?
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If a solar system were surrounded by a cloud of debris, is it possible for a planet's orbit to intersect it?

I'm doing research for a story that I'm writing and I'd like some physics advice on whether a hypothetical system of celestial bodies is possible. Suppose the following: A system of planets orbiting ...
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2answers
99 views

Where will the planned Deep Space Atomic Clock orbit “after” Earth? [closed]

I've seen multiple sources repeat the information that the Deep Space Atomic Clock will 'at first' orbit Earth, before moving on out of Earth orbit. The Deep Space Atomic Clock (DSAC) is a ...
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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 ...