Questions tagged [orbit]

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

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18
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3answers
4k views

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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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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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
37 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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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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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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2answers
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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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2answers
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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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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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1answer
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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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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 ...
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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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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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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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Does the sun have cycles causing temperature changes on Earth?

Can the Sun go through seasons or cycles to cause a temperature change? Could the Sun have to go through any kind of thermal cycle to change the climate on Earth and by how much?
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What is the coordinate acceleration for pure radial motion?

As seen in this answer and also in this book chapter 6, page 6-10 expression 22, when you are falling in radially from being at rest at infinity your velocity in coordinate time, as seen from a ...
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Is it possible to do moon sighting in advance for 5 years with 100% accuracy? [duplicate]

It is Ramzan and the usual heated disagreements between clerics here in Pakistan as to the sighting of the crescent. This time the minister of Science and Technology (who is not a scientist himself ...
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1answer
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Why hasn't the Earth fallen into the sun yet?

So the Earth's been orbiting the sun in a relatively stable orbit for billions of years now. during that time, it's been plowing through dust, and hit by comets and asteroids, presumably mostly from ...
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1answer
157 views

Could the Sun have liquid iron in orbit?

How close of an orbit to the Sun could an iron meteor get before it melts into a ball?
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Did the Moon ever approximate a geosynchronous orbit above the early Earth?

Simulations suggest the early Moon formed about 20,000 to 30,000 km away from Earth which is less than the current geosynchronous orbit of 42,164 km. The Moon is now 384,000 km away from Earth. Does ...
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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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1answer
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Is there an optimum orbit for a hipparcos/GAIA-like parallax observatory

The GAIA spacecraft is currently mapping the stars in the Milky Way by parallax. It orbits in the Earth-Sun L2 lagrange point. The parallax observed from the spacecraft orbiting around the sun allows ...
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2answers
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'Geocentric' view of orbits

Given our real solar system how would planet orbits plot look like if we fix earth in the middle (put earth in the middle and draw a real orbit of a given planet) ? What would be the shape of its ...
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Earth orbit around the Sun and its position in the Galaxy

Given the orbit of the Earth around the Sun and the position of the Sun in the Galaxy, in which season are we (the Earth) closer to the galactic center?
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What orbit is the smallest or takes the least time to complete?

What orbit in our solar system would take the least time to perform 1 orbit? What is the fastest possible orbit to complete in the universe?
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1answer
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What is the closest an asteroid or comet has passed the Sun and survived?

After SOHO began watching the Sun from space with its coronagraphs 24/7 it was discovered that there are comets passing very close to the Sun quite regularly, and while some are destroyed, some are ...
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1answer
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How far does the Earth travel around the Sun during each month of the year?

After reading about the Earth's orbit and how it moves faster in January than it does in July (based on its distance from the Sun), I started to wonder... How far does the Earth travel around the Sun ...
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Why is the moon drifting? Shouldn't orbital decay bring it closer? [duplicate]

I noted that the moon drifts away from Earth a few centimeters each year. However, I'm thinking that the emission of gravitational waves would deter such thing and cause the exact opposite. ...
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1answer
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Various moon orbits

Orbits can follow certain patterns, as I am aware. Some include a circular orbit around the bulk of the planet, a polar orbit spinning about the pole... What I'd like to know, for a planet with two ...
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1answer
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Does the Sun twinkle?

Does our solar system have enough bodies in orbit to appear to twinkle to another distant solar system viewed from the side? https://en.wikipedia.org/wiki/List_of_asteroid-discovering_observatories ...
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Can the moon's gravity influence be observed on the space station's orbit?

In browsing through Astronomy Stack Exchange, I came across this question about orbiting the moon (Is it possible to achieve a stable "lunarstationary" orbit around the moon?). In further ...
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1answer
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Could there be additional Neptunian satellites between Larissa and Hippocamp?

Plotting the moons of Neptune in terms of semimajor axis and eccentricity using the values given on the Wikipedia page for the moons of Neptune, there appears to be a fairly large gap between the ...
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1answer
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How come the Sun does not make the Moon crash on the Earth?

As the Moon loops around the Earth, on one side of the Earth it moves toward the Sun (let's call it downward side) and on the other side it moves away from the Sun (let's call it the upward side). ...
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Is there any known moon of a moon? [duplicate]

As far as I understand, a moon is an object in permanent orbit around a planet, dwarf-planet, asteroid, etc. If there was another object permanently orbiting this moon, would that be a moon-moon? Is ...
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1answer
247 views

Can a photon have a stable orbit around a black hole?

Can a black hole free from an accretion disk collect photons in the photon sphere in a prolonged stable orbit? Could enough photons be in orbit to shade the actual black hole with light? Would a ...
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1answer
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How was Cruithne's orbital time calculated?

How was it determined that Cruithne takes 770 years to complete its cycle with Earth? Janus and Epimetheus were disovered long enough ago, and have short enough cycle times, that we've had time to ...
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2answers
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nonagesimal in Kepler's parallax computation

I'm starting to learn Kepler's Astronomia Nova using William Donahue's translation . In the translator's introduction, it is demonstrated how Kepler did his parallax computation. I failed to ...
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1answer
160 views

How close to circular is the Earth's equator

Earth's orbit is about 99% circular. How circular is Earth around the equator? I know it bulges around the equator and is a spheroid. I also know it is not smooth and has oceans and mountains and all ...
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What variables are needed to calculate simple horseshoe orbit times?

EDIT This was NOT a duplicate of Horseshoe orbit cycle times. But that other question has been deleted, regardless. My original question asked for the answer to the equation(s), and provides many of ...
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2answers
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Is it possible to see a spacecraft orbiting the moon with a pair of binoculars?

On this clear early morning over London, I was studying the moon with a pair of binoculars and noticed a tiny dot of light that appeared to trace a slow orbit around the moon. I reckon it moved ...
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1answer
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does the orientation of orbital plane of our solar system rotate with the galaxy

As I understand it, our solar system travels through the milky way with the orbital plane tilted about 60 degrees so that we are sort of traveling in the direction of earth's north. My question is if ...