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Questions tagged [rotation]

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

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Why do the Sun and gas planets rotate faster at equator than at poles?

From this site, it states that: The Sun spins faster at its equator than at its poles. I have also read somewhere that the gas giants (gaseous planets like Jupiter, Saturn, Uranus, and Neptune) also ...
apk's user avatar
  • 949
6 votes
0 answers
153 views

How was the axial tilt of planets measured?

https://en.wikipedia.org/wiki/Axial_tilt#Solar_System_bodies gives the axial tilt of all planets with two decimal precision, but how and when were they measured so precisely ? I guess it's "easy&...
Dr. Goulu's user avatar
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4 votes
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Why does the outside edge of a Kerr black hole ergosphere rotate at the same speed as the inner edge?

Reading through the Wikipedia on a Kerr black hole ergosphere, and this nice question on the maximal spin rate of a black hole leads me to ask: why does the outer edge of the ergosphere rotate at the ...
joseph.hainline's user avatar
3 votes
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How can Jupiter rotate faster at the equator than at the poles (in degrees per second)?

Jupiter rotates slightly faster at the equator. If inertia is conserved as average angular momentum, what is the physical mechanism that creates a gas which is ~1% faster angular momentum at the ...
Wolfgang Weber's user avatar
3 votes
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How long would it take for a planet captured by a red dwarf to become tidally-locked if it started out rotating retrograde?

So say for the sake of argument that we have a red dwarf orbiting a G of K-class star. An Earth-sized planet forms, maybe at one of the dwarf star's Lagrange points to its primary, and eventually ...
PrincipledStarfish's user avatar
3 votes
0 answers
52 views

Would tidally locked Earth-like exoplanets necessarily have hot pole/cold pole atmospheric circulation?

A tidally locked planet orbiting a red dwarf star in its habitable zone would have a rotational period equal to its orbital period, on the order of days or weeks. Given a thick enough atmosphere ...
RobertF's user avatar
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3 votes
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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 ...
n_bandit's user avatar
  • 625
3 votes
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Earth-Centered Earth-Fixed coordinates with respect to heliocentric coordinate system at vernal equinox

I am trying to calculate the position of a point on the Earth's surface with respect to the Sun's center at a certain date and time. For what I am trying to do it is OK to ignore precession of Earth's ...
Abstraction's user avatar
2 votes
0 answers
57 views

Calculation of intersection point Q of planetary equator with ICRF equator for other planets

I'm converting the W for each planet in this IAU report into Celestia's MeridianAngle, which is converted like this: $$ \textrm{MeridianAngle}=W-Q $$ Where Q is the point where the planet's equator ...
ILikeSaturn's user avatar
2 votes
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Where can I find galaxy rotational data?

I want to do a small project of generating rotational curves for different galaxies, and need data for some prominent stars in other galaxies (data needed: distance from center, rotational velocity) ...
Hardek A.'s user avatar
2 votes
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Do retrograde spin-orbit resonances exist?

The end state of rotation of an initially fast-spinning prograde terrestrial planet (in the absence of additional forcings such as "thermal tides" in an atmosphere, e.g. Venus) is a spin-...
user avatar
2 votes
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Has the computed change of the axial tilt ever been measured?

Earth, the 3rd planet from the Sun, sometimes faces earthquakes and seaquakes that are so strong that they reportedly change the axial tilt and/or the rotation velocity. These changes are merely ...
Ioannes's user avatar
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2 votes
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Moon rotation tidal braking

Do we know if the moon had an initial rotation or did it coalesce tidally locked. If it had an initial rotation how long would it take to become tidally locked?
user36138's user avatar
  • 171
2 votes
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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 ...
posfan12's user avatar
  • 193
1 vote
1 answer
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Calculating field rotation between two times

I have the formulae to calculate the rate of field rotation at any given time, and using a python script with Skyfield I can generate a a value incrementing every 10th of a second based on the live ...
Tanenthor's user avatar
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1 vote
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is there anything that might cause a planet to stop getting sunlight permanently, or to only have light infrequently? (on the whole planet or part)?

(writing a story) Is there anything that might cause all or part of a planet to stop getting sunlight, or to have a permanent/ridiculously long-lasting perpetual twilight? nuclear winter? volcanic ...
Zeantra's user avatar
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1 vote
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Reference point for the directions

Are directions [North, South, West, East] derived from Earth's rotation around its axis? What makes north north and the south south? Is it arbitrary or is there some specific reference point?
Bill Thompson's user avatar
1 vote
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Determining the rotation curve of a galaxy via given spectroscopic data

Here is the data analysis question from IOAA-2011, 1. Weighing a galaxy: The image 8.2 shows a photograph of the spiral galaxy NGC 7083, which lies at a distance of 40 Mpc, and image 8.3 a fragment of ...
samuraiwarrior's user avatar
1 vote
0 answers
91 views

How to model galactic rotation curves?

I have R (kpc)- distance from galactic center and v(km/s) rotational speed at that distance. I was thinking of creating a simple model comprising of 3 terms 1 for Keplerian component another for rigid ...
Hardek A.'s user avatar
1 vote
0 answers
46 views

Is there an API to obtain Solar System body axial tilt data?

I would like to get information about rotation period and axial tilt for main Solar System bodies and major moons, over time. Is there an API availabe for this? I've checked JPL's Horizons API and ...
Eloy Villasclaras's user avatar
1 vote
0 answers
38 views

Doppler Shift Vs Gravity Assist for Frequency Shifts from Rotating Galaxies

Frequency Shift of Light Leaving Rotating Galaxies: Differences in Doppler Shift due to Radial Velocity Vs Frequency Shift due to Gravity Assist from a Rotating Galaxy A description of estimating ...
JohnRobyClayton's user avatar
1 vote
0 answers
139 views

How does a spinning black hole affect space-time compared to a non-spinning black hole?

I often see questions on this site that only apply to non-spinning black holes and often wonder how the answer would be different for a spinning black hole. As the title says, what are the major ...
dalearn's user avatar
  • 823
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What direction do Herbig Haro outflows go from?

After doing some research about Herbig Haro objects, I found that the outflows are formed perpendicular to the circumstellar disk. Is that the same direction as the star's rotation, or is it the ...
Astrovis's user avatar
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Convert from magnetic coordinates to true coordinates

I am working with the IGRF (International Geomagnetic Reference Field) model and from a journal article found here, I am able to compute the earth's magnetic field at any point in spherical ...
mwoods's user avatar
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0 votes
0 answers
164 views

How much would you weigh at the equator of the fastest spinning pulsar?

Assuming you have a mass of 70 kg, what would your weight be on the equator of PSR J1748−2446ad?
A.J Perez's user avatar
0 votes
0 answers
117 views

Converting Invariable plane to J2000 ecliptic

I've been following the answer given by Mike G here: How to calculate the orientation of planets at current epoch to get planets to have the correct orientation in my program, but all the angles are ...
nussun's user avatar
  • 1
0 votes
0 answers
26 views

Accelerations on the Moon due to its orbit and its spin

A gyroscope is placed on the equator of the Moon. It detects among others 2 accelerations: one due to the orbit and one due to the spin. What is the module of the second one compared to the first one? ...
Gilbert Vidal's user avatar
0 votes
1 answer
170 views

Will there be any more planets come into our solar system and make it their "home"?

Could we have more planets come into our system and get trapped by our suns gravitational field and rotate?
TheBigJoe1489's user avatar