Questions tagged [rotation]

Questions regarding the action of or an object rotating along an axis.

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20
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3answers
2k views

Why does a planet rotate and revolve?

Why do planets rotate and revolve in the universe?
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2answers
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What is the current accepted theory as to why Venus has a slow retrograde rotation?

According to this NASA overview, the planet Venus is unique (amongst the major planets), Venus has a slow retrograde axial rotation, taking 243 Earth days to make one rotation (which is longer than ...
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Cancelling out earth rotation speed, Altazimuth mount

I have a Dobsonian telescope. It is using Altazimuth mount. Basic idea of using it is to target the object by moving telescope vertical axis perpendicular to the ground, and an elevation axis that is ...
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5answers
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Why do (most of) the planets rotate counterclockwise, i.e. the same way the Sun does?

Referring to the mechanisms explaining the solar system formation and to the initial rotation of the gaseous cloud that collapsed, I understand easily why the planets orbit the Sun the same way this ...
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Inverse of the sunrise equation - finding locations with a given sunrise time on a given day

I'm working on a project for fun where I represent some sleep data geographically. For a given day, I have a date, a time for falling asleep that night, and a time for waking up the next day. The idea ...
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1answer
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Do the axes of rotation of most stars in the Milky Way align reasonably closely with the axis of galactic rotation?

The axis of rotation of the Solar System makes a large angle of about 60 degrees relative to the axis of rotation of the Milky Way. That seems unusual - for example, most of the bodies within the ...
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3answers
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Why is twilight longer in summer than winter and shortest at the equinox

I recently decided to set my alarm clock to wake me up when it is "dark" out. In the end, I decided to set my clock to the earliest time that nautical sunrise is in my state (Illinois) and stick with ...
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1answer
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What causes objects to become tidally locked?

I'm trying to write a gravity simulation (suns planets etc), and was hoping tidal locking could be one feature demonstrated. Using a simple equation for gravity has produced some interesting results, ...
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What is the accepted theory as to why Uranus' axis is tilted so severely?

The planet Uranus is another solar system anomaly, where according to the NASA profile has an axial tilt of 97.8 degrees, also considered to be retrograde. This NASA summary "Uranus" suggests the ...
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1answer
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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 ...
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1answer
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What is the YORP effect exactly? Is it just the non-central component of the Yarkovsky effect?

This answer to Where have all the Vulcanoids gone? links to the aptly-titled The YORP Effect Can Efficiently Destroy 100 Kilometer Planetesimals At The Inner Edge Of The Solar System which says in ...
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Shape of neutron stars

I've heard that the more an object spins, the less of a true sphere it is. Using this logic most of neutron stars would be far from spherical,in general what shape are most neutron stars?
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How would Earth's climate differ if it's axis were tilted around 90 degrees like Uranus? [closed]

As the title states, what would the effect on Earth's climate be if it's axis were tilted approximately 90 degrees like Uranus? I'm specifically wondering about the effects on seasons, temperature, ...
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Are there any known planets whose axis is oriented such that one pole always faces its star?

Earth rotates around the sun and around its axis (A North, South axis) giving us days, nights and seasons. Are there any known planets that rotate with an axis pointing toward its sun so that one ...
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Could the merger of two rotating black holes create another that breaks the rotational speed limit?

The black hole GRS 1915+105 was observed to be spinning at near the theoretical maximum spin rate. Assuming you had two such black holes spinning clockwise, and also orbiting each other clockwise, ...
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1answer
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What makes the Earth rotate infinitely around its axis?

I was reading two sites before I posted the question here. One site says something like that the collisions in Universe eventually set the planets rotating, another site says that our planet is formed ...
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2answers
871 views

What is the axial tilt of a planet measured relative to?

I am very much a beginner on the astronomy front but I understand about planets having different axial tilts, hence why Venus turns the opposite direction from the Earth and Uranus turns sideways. ...
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What is the difference between the Yarkovsky effect and YORP effect?

As far as I understand, both the Yarkovsky effect and the Yarkovsky–O'Keefe–Radzievskii–Paddack (YORP) effect exert forces upon bodies as a result of thermal photon radiation. How do both effects ...
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1answer
192 views

Are there collected data about the direction of rotation of black holes and the direction of the magnetic field?

Is there a relation between the direction of rotation of black holes or neutron stars and the magnetic dipole moment of BH or neutron stars? BTW, are there different directions of this two parameters ...
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1answer
205 views

Uranus' axis of rotation-when discovered?

Who discovered it, and how was that accomplished. I had assumed it was known before Voyager 2 arrived at the planet since it isn't mentioned in JPL voyager 2 Uranus Approach
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If the earth stopped rotating, would we really fly inertially at 1000mph? [closed]

I heard this on Prof. Neil Tyson's StarTalk podcast (this episode) and had a question about it. In a Q&A session, a listener had asked what would happen if Superman really did stop the earth from ...
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1answer
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Calculating the orientation of the night sky

How would one calculate the rotation/tilt of the earth to simulate the Night Sky in a self-written tool or app. I am trying to built an app for my telescope to show me on my phone what I am looking at....
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Does the Sun rotate?

The planets rotate as an after effect of their creation, the dust clouds that compressed span as they did so and the inertia has kept it rotating ever since. It's fairly easy to prove that planetary ...
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1answer
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How did Mars come to have a 24 hour 39 minute day?

Mercury rotates three times for every two revolutions around the Sun, apparently due to a gravitational resonance with the Sun.Venus takes about 225 days to rotate, and rotates in the opposite ...
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2answers
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If Earth didn't rotate, would we feel heavier? [closed]

Suppose the Earth's rotation slowed for some reason. Would the lack of centrifugal force cause us to feel heavier than normal? Likewise, if Earth's rotation increased, would we feel lighter as ...
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1answer
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What is a black hole's "shadow" and the best angle to view it to measure the spin?

This excellent answer mentions several ways to try to observationally measure the spin of a rotating black hole. The third one is intriguing, but I don't understand how this works: The spin of a ...
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1answer
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Why does the Sun have different day lengths, but not the gas giants?

The Sun's rotation period varies from about 25 days at the equator to about 38 days at the poles. As I understand it, this is because the Sun is not solid, and because of the way centripetal force ...
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Would an exoplanet without axial tilt have no seasons?

Would an Earth analog exoplanet which rotates around a solar analog, but without axial tilt, have no seasons? Would it be similar to how Los Angeles does not have very noticeable seasons compared to ...
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Do solstices and equinoxes shift over time?

Right now, I think the winter solstice is around December 21. Has it always been around this date constantly? Since the earth's axis's 23.45° tilt will be on the exact opposite side in 13000 years (...
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2answers
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What is the definition of a "pole" of a celestial body?

What is the definition of a "pole" of a celestial body? Earth's pole is defined as it's rotational pole. The North and South Poles are the two points on Earth where its axis of rotation ...
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Why most planets don't spin retrograde? [duplicate]

Edit: just found duplicate Since orbital velocity is greater on small orbits, and smaller on large orbits, why don't planets spin retrograde around their own axis? One portion of planet's mass is ...
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Are there any bodies in the solar system whose rotation is almost tidally locked or barely tidally locked?

The Moon's rotation is firmly tidally locked to the Earth and the Earth's rotation is firmly tidally unlocked with respect to the Moon. I gather that Mercury's rotation is tidally locked in a 3:2 ...
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2answers
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If a giant object would approach the Earth, would Earth start to turn faster or slower while the object starts to become nearer and nearer?

I am asking myself this question: if a giant celestial object would approach the Earth, would Earth start to turn faster (then day duration would be diminished) or slower (day duration increased) ...
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1answer
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Rendering asteroid orientation as seen from Earth

I am writing a program to render an asteroid as seen from various parts of the solar system. My goal is to roughly reproduce the image of Cacus according to information on its DAMIT detail page. ...
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0answers
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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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1answer
229 views

How to calculate the orientation of planets at current epoch

For an application I am working on I am creating a simulation of the solar system. In this simulation, a user needs to be able to 'move' to any position on any planet, and have the sky be accurately ...
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1answer
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Do some comets spin? If so, how fast?

The GIF below is copied from my question earlier What might a CN filter be in the context of comet watching? Is it showing dust, or gas, or something else? where I'd said: In this post on the website ...
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2answers
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Is the Sun prograde or retrograde with respect to the rotation of the Milky Way?

I recently learned about the terms prograde and retrograde. I've seen these terms used to describe the rotations and orbits of moons with respect to their planet, and planets with respect to their ...
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4answers
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Is it possible for stars not to rotate?

I'm just curious about that the existence of non-rotating stars. Is it physically possible for a star not to rotate at all? Does magnetic braking eventually stop the stellar rotation?
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1answer
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Does the sky get darker faster during the winter?

When one lives away from the equator, say at around 37° latitude, does the sky get darker faster after the sun sets in the winter as compared to the summer? Why is this the case? I believe that if ...
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1answer
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How can a rotation period of a planet's satellite/moon be "chaotic" (like Hyperion around Saturn)?

According to wikipedia (see info below image) Hyperion's rotation period around Saturn is "chaotic". What does that mean? The period (in days/hours) is different every rotation without any law ...
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2answers
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Motion of rogue planets

Two Questions: 1) Are rogue planets in motion, i.e. are they just wandering freely in space or stationary? 1) Do rogue planets have defined path or a one which can be anticipated? I understand that ...
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0answers
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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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2answers
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Why are tides biggest during the equinoxes?

I've read that during the equinoxes, tides are at their maximum. Shouldn't this only apply to latitudes near the equator? I mean, when the solar declination is near to 0º and we have a full or new ...
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0answers
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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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3answers
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Will Earth rotate backwards in the future?

Hello recently I heave heard the earth will eventually start rotating in the opposite direction (ie sunrise from the west) . I am not sure if this is true, but a lot of sites are claiming it to be ...
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4answers
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How are galactic rotation curves determined from radial velocity measurements?

I have been reading about the deviation of galactic rotation curves from the predicted Keplerian curve to a flat curve at large galactocentric distances. They were the first indicators of the ...
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1answer
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As the Moon and the Earth are predicted to get into tidal lock, how slow would the Earth rotate?

This answer to Will the Earth ever be tidally locked to the Moon? supports the widely held thinking that during the Sun's red giant phase or later the Earth and the Moon should be tidally locked to ...
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1answer
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The equation for calculating how many times Earth (or our solar system) has revolved around the Milky Way

I have seen it said on Quora and Reddit that it's about every 220-250 million years to go around the Milky Way from Earth. Wondering what the rough equation is for calculating it. That is, I guess, ...