Questions tagged [orbit]

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

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66
votes
6answers
9k views

Why is only one side of the Moon visible from Earth?

Why do we only ever see the same side of the moon? If this is to do with gravity are there any variables which mean we might one day see more than we have before?
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2answers
3k views

Is it possible that the Sun has a binary partner (the Nemesis Theory) that has eluded detection? [duplicate]

I just recently learned about the theory that our Sun has a small companion star with a 26 million year orbit. This theory came about when it was realized that mass extinction events happened ...
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2answers
4k views

Why is the Moon receding from the Earth due to tides? Is this typical for other moons?

After reading the Q&A Is the moon moving further away from Earth and closer to the Sun? Why? about the tides transferring energy to the Moon and pushing it from Earth, I have a question: How is ...
33
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1answer
7k views

Why do the planets in our solar system orbit in the same plane?

(Yes I'm excluding Pluto from this the same way it was excluded for not being a planet) Observing the planets orbit of the Sun they all seem relatively planar and roughly all orbit along the same ...
9
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5answers
2k views

Does the Sun turn around a big star?

The Moon orbits the Earth. The Earth orbits the Sun. Does the Sun orbit another bigger star? If so, does this star orbit, in turn, a very big star? ... etc ... What are all the intermediate ...
8
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1answer
2k views

Are there accurate equinox and solstice predictions for the distant past?

I am trying to find information on the equinox/solstice dates before 1600, more exactly referring up to 10,000 BCE so as to create a sort of calculator on an Excel spreadsheet. I have read about the ...
16
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1answer
4k views

Why is the solar system often shown as a 2D plane?

Whenever I have learned about the solar system I always see the orbits displayed as a virtually flat plane. Are all of the orbits in the solar system really like this? If so, why? It seems like a ...
17
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4answers
2k views

Why are orbits elliptical instead of circular?

Why do planets rotate around a star in a specific elliptical orbit with the star at one of it's foci? Why isn't the orbit a circle?
10
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6answers
17k views

Why doesn't the sun pull the moon away from earth?

If the suns gravitational pull is strong enough to hold much larger masses in place (all the planets) and at much greater distances (all planets further away from the sun then earth) why does it not ...
9
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1answer
3k views

Are planets moving away from the sun?

I saw on the tv show Through the Wormhole (hosted by Morgan Freeman) that the planets in our solar system have been continuously moving away from the sun for millions of years. however, when I try to ...
8
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3answers
462 views

Is there a ceiling for stable L4 or L5 masses?

L4 and L5, the Lagrange points 60 degrees leading and trailing an orbiting body, are famous for being stable. A well known example are the Trojan aseroids at the Sun Jupiter L4 and L5. Nodding to ...
7
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4answers
7k views

What point does Earth actually orbit?

If we consider the two largest masses in our solar system - the Sun and Jupiter, by themselves, they will orbit a common barycenter which is somewhere offset from the Sun's center in the direction of ...
10
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1answer
995 views

Best approximation for Sun's trajectory around galactic center?

What is the current best approximation for the path the Sun takes around the center of the Milky Way? I have found some information on the approximate position of the Milky Way's center, the speed of ...
4
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1answer
239 views

How would one calculate the synodic period of the Earth and an elliptical orbit?

For example, when would someone with a telescope be able to see Starman and his Roadster (when will the Tesla roadster's elliptical orbit cross ours again, and how would that be calculated?) For two ...
3
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1answer
214 views

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. ...
29
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3answers
5k views

Pluto's orbit overlaps Neptune's, does this mean Pluto will hit Neptune sometime?

We know that the orbits of Pluto and Neptune overlap. This means that pluto sometimes crosses the orbit of Neptune; will Pluto hit Neptune in any circumstance?
15
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5answers
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When will all eight planets in our solar system align?

Ignoring expansion of the universe, entropy, decaying orbits, and interference from any bodies colliding with or otherwise interfering with their orbits, will the eight planets known planets in our ...
15
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5answers
442 views

Orbiting around a black hole

Is it possible (for either a satellite or a planet) to orbit around a black hole? Do they attract everything around themselves into the center? Or they just affect gravitational force just like stars?
23
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6answers
4k views

Can a natural satellite exist in a geostationary orbit?

While browsing through Physics SE, I noticed a question about satellites in geostationary orbit (unrelated to the one I'm asking here), and for a moment I interpreted it as referring to natural ...
20
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1answer
973 views

Is Earth's orbital eccentricity enough to cause even minor seasons, without axial tilt?

I was reading the answers to this question about an exoplanet having seasons without axial tilt, and several responders mention that orbital eccentricity could cause a similar effect, but that the ...
14
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5answers
8k views

Does the gravity of the planets affect the orbit of other planets in our solar system?

When one planet passes near another during its trip around the sun, does their gravitational pull is strong enough to disrupt noticeably each other's orbit ?
3
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2answers
799 views

Why are these objects moving at Vastly Different Speeds along the same orbit?

UPDATE: The on-line simulation seems to be working beautifully now! I'd recommend anyone to go back and take another look to enjoy both the mathematical beauty of orbital mechanics, and the aesthetics ...
23
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4answers
3k views

Is there a upper limit to the number of planets orbiting a star?

Our sun has 8 planets orbiting as well as a number of dwarf planets. Are there any calculations that hint as to whether this number is close to some theoretical maximum value or are we simply an ...
12
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5answers
4k views

What mechanism causes oscillations of the solar system's orbit about the galactic plane?

In a recent paper (news release here) Lisa Randall and Matthew Reece propose that a dark matter disk coinciding with the galactic plane together with the solar system's oscillations through the ...
15
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8answers
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Moon's orbit around the Sun

The Earth revolves around the Sun and the Moon revolves around the Earth. Out of curiosity I started thinking about the orbit of the Moon around the Sun and expected (assumed) it to be as follows: ...
15
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3answers
3k views

How old is our Sun in Galactic years?

A year is measured as the amount of time it takes Earth to orbit the Sun once, a Galactic year is the time it takes our sun to make one full orbit of the center of the Galaxy. In Galactic years, how ...
13
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1answer
3k views

What is the difference between Sphere of Influence and Hill sphere?

Wikipedia's definition of Hill sphere is: An astronomical body's Hill sphere is the region in which it dominates the attraction of satellites. To be retained by a planet, a moon must have an orbit ...
9
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3answers
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What orbital period would produce one New Moon (and one Full Moon) each year? What other effects would this produce?

I am interested to know whether it's possible for the moon to orbit the earth at such a rate that we would see only one New Moon and one Full Moon a year. If so, what other effects would we experience?...
9
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1answer
646 views

Where did this famous Planetary Precession Formula come from?

The following equation (which I shall term the Planetary Precession Formula, PPF for short) famously appeared in a 1915 publication by Einstein where he indicated how it could be derived from his ...
7
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2answers
756 views

How do I calculate the positions of objects in orbit?

In a model of the solar system, given the Sun is at the point $(0, 0, 0)$, an given the six orbital elements for each object in orbit ($a$, $\epsilon$, $i$, $\Omega$, $\omega$, $M_0$), how can I ...
16
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3answers
2k views

How does a gravity slingshot actually work?

From what I know of elliptical orbits, an object speeds up near the periapsis and slows down at the apoapsis, much like we learned in high school physics how a sphere would roll down and back up a ...
10
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2answers
5k views

Why are most planetary orbits nearly circular

In our solar system, with the exception of Pluto all planets follow a relatively circular orbit around the Sun, at the same inclination. They also all rotate in the same direction, none are '...
8
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2answers
4k views

How did Kepler determine the orbital period of Mars?

As I understand it, Kepler used the orbital period of Mars, along with observational data of Mars' and the sun's position in the sky to derive the orbits of Earth and Mars. (As described, here: https:...
7
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2answers
690 views

Orbiting supermassive black hole or galactic center of mass?

One of the ways they measure the (supposed?) supermassive black hole at the galactic center of the milky way is to measure those tens of stars right at the galactic center that are orbiting what ...
5
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2answers
302 views

Can General Relativity indicate phase-dependent variations in planetary orbital acceleration?

In a previous question about differences in Newtonian and GTR gravitional force for the case of star-planet gravitational interactions an approximate relationship was noted between the expressions for ...
4
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1answer
396 views

Could a habitable satellite of a gas giant have a stable subsatellite?

I have set a science fiction story on a moon, orbiting a gas giant (which orbits its star at approximately the same orbit as the Earth around the Sun), and given this moon its own satellites. The ...
3
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1answer
3k views

How is the path of an asteroid calculated?

How do scientists and astronomers recognize the perfect path or orbit (if it's orbiting an object) of an asteroid or a comet?
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2answers
732 views

'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 ...
15
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2answers
3k views

What are “non-Keplerian” orbits? What are some familiar examples in our solar system, and can some still be closed?

This excellent answer to Forms of stellar orbits around the galactic center invokes the following concepts: non-Keplerian orbits closed orbits I have a fairly good idea what these mean and so might ...
13
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1answer
384 views

Changes to Earth's orbit

Any time a spacecraft comes in close proximity to a planet and if the spacecraft has the right angle then it is able to use the planet's velocity to move itself further into space. According to ...
12
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1answer
408 views

Orbital velocity of a planet - why is my calculation off by about 10%?

I am not sure if I am doing something wrong, or misunderstanding Reider and Kenworthy (2016). I'm just trying to reproduce the orbital velocities listed in Table 1. The second paragraph of Section II ...
11
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1answer
437 views

Why do galaxies have arms?

A couple of years ago I started playing a game called Kerbal Space Program (KSP) and my understanding about how orbits actually work increased dramatically. Because of KSP I was looking at a picture ...
8
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1answer
400 views

What is the shape (along the plane, not up-down) of stellar orbits in flat spiral galaxies

What I mean is, with a central mass orbits are relatively simple, but orbits around the galaxy are different, in essence as the star orbits through the dark matter halo, the further it moves away from ...
5
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1answer
865 views

Simulate an orbit with orbital elements

I want to simulate the orbits of the planets from our solar system. I want to use orbital elements to calculate the current position(xyz) at a time t. The simulation doesn't have to be too exact, but ...
4
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1answer
247 views

What (actually) is Jupiter doing to this year's Perseids meteor shower?

After reading the Astronomy Magazine article Perseid meteor shower set for its best show in nearly 20 years and NASA's Look Up! Perseid Meteor Shower Peaks Aug. 11-12, I understand that Jupiter's ...
4
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2answers
1k views

Could an asteroid knock the moon out of its orbit?

As describe in this CNN article, an asteroid is going to pass near the Earth on Halloween. The article says that As it misses Earth by about 300,000 miles (slightly farther away than the moon), ...
4
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1answer
187 views

Satellite's orbit

What is the maximum distance for a satellite to orbit the earth? Does earth's gravity has the impact on satellite? I do know that earth's gravity will never be zero and it's gravity is inversely ...
3
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1answer
397 views

How can the next supermoon be analytically predicted?

The lunar motion can be predicted with basic celestial mechanics, but the perigee and apogee are not always the same, basically because the attraction of the Sun makes some oscilations in the semi-...
3
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1answer
2k views

Why does the moon not leave its orbit around the earth due to the gravitational force from the sun? [duplicate]

See additional information below added after the answer to the question. When the moon is between the earth and the sun, the gravitational force on the moon from the sun is greater than the ...
2
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2answers
990 views

What is exactly the “longitude of the perigee”

Some moon phase calculation algorithms (apparently derived from Duffet-Smith's book, example here) seem to use a parameter called "longitude of perigee at epoch". What exactly is this? Can I assume ...