Questions tagged [planetary-science]

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How scientists find the direction of rotation of planets?

How do we know that Mercury, Earth, Mars, Jupiter, Saturn, and Neptune rotate counterclockwise and Venus, Uranus, and Pluto rotate clockwise? How do scientists determine the direction of rotation of ...
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Does magnetosphere have an influence on where meteorites would impact on Earth?

I have an interest in geology and I have taken an interest in learning about meteorites recently. This may be a redundant question but it seems as if there are meteorite rich areas where there seem to ...
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What are the orbital velocities of the other planets? For objects in a 'Low-Earth-Orbit' around planets other than Earth, e.g.?

I was pondering this question recently, but most sites I can find only mention the speeds/velocities of the planets around the Sun when I look for 'orbital velocities' of the planets. I tried ...
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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 ...
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Resources for image representations of planetary systems that indicate the temperature of each part of the system

I was wondering whether anyone knows a resource where I can get images in the form of illustrations or representations of planetary systems, where these images indicate or convey the temperature of ...
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2 votes
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What is the maximum size for a solid celestial body such that it still can be tunneled down to the core?

Old science fiction had lots of stories that involved people exploring the center of Earth, like for example Journey to the Center of the Earth, by Jules Verne. As Earth sciences advanced, this sort ...
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Is the Michael H. Hart range for the Habitable Zone (Goldlocks Zone) still used?

We're having an argument on another site about the Hart definition of the CHZ. In 1979, Hart provided a very conservative estimate of habitable zone: 0.958 - 1.004 AU. This was used to substantiate ...
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1 vote
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Calculate Earth Zenith Point of Another Planet with Azimuth and Elevation of another Observer Point

I need to find the Longitude of the closest point on Earth (zenith) to Jupiter with the Azimuth and Elevation data from another observation location at a given point in time. Below is the source of my ...
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11 votes
3 answers
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At what point in history was the idea of planets being spit out by the sun abandoned?

For context, at some point during the 20th century (and maybe earlier as well), the most popular planet formation theory and the one that was taught at (at least some) schools was the theory that the ...
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How might a lower gravity planet sustain a warm, earth-like atmosphere?

I'm designing a hypothetical lower-gravity planet with 0.47M, 0.79r and 0.76g, with a similar density to Earth. I've already determined that this mass, radius, and density will allow my planet to ...
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What are the time periods of precession of equinoxes of other planets?

Earth has a time period of 26000 years approximately for precession of its equinoxes. What are the time periods of precession of equinoxes of other planets?
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What else can we learn from a Foucault pendulum? Have they ever been used to determine anything more than that the Earth rotates on its axis?

Background Each semester we have to make up projects for each course. This semester I took Cosmology and Astrophysics and we covered a vast amount of topics, from luminosity of stars to Einstein's ...
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If the Earth became tidally locked with the moon, would that last forever?

If the Earth and the moon became tidally locked, would this last theoretically forever (assuming no external gravitational force modifies their orbits, for example, ignoring the effects caused by the ...
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Could a magnetosphere be created for Venus by recreated by spinning-up the planet to a 24 hour day?

If Venus in it is current state, started rotating at the same rate as Earths 24hrs rotation, would it develop a magnetic field of roughly the same strength as Earth's? If so, would that help in any ...
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How do rocky planet break up? Would they fragment into "a gazillion" rocky pieces pieces, or crack open like an egg?

I remember seeing a movie (probably star wars) where this bad guy (Darth Vader) shoots a superb laser (Death star) to obliterate a populated planet, Alderaan (how inhumane). The problem is, the planet ...
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3 votes
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Calculating velocity of Earth from JPL DE

We have discussed how to calculate positions from JPL development ephemerides in this question. Following this answer, I am now using SPICE's algorithm for calculating the derivatives of the Chebyshev ...
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Can a destroyed earth reform into another habitable planet?

Let's say a planet-sized object collide with earth, disintegrate it, then reform at the same orbit as earth. Will it eventually formed into a habitable, life-supporting planet with living organism?
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Why does the factor of $\frac{1}{4}$ appear in this equation?

This is an equation my professor wrote to calculate the equilibrium surface temperature of a planet:$\frac{S}{4}(1-A) = \sigma T^4$. (A is the albedo of the planet and S is the intensity of starlight ...
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How un-dense can a terrestrial planet get before it turns into a mini-Neptune?

EDIT: well, now I have more For reference: A terrestrial planet is a planet that is made out of silicates and metals. A Mini-Neptune is, as far as I know, the smallest type of giant planet (arguably,...
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1 answer
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For how many solar system bodies do recent JPL Development Ephemerides include libration?

Since the Earth and the Moon are so gravitationally and tidally engaged and the laser ranging data so precise, the JPL Development Ephemerides are based on extensive modeling of the Earth-Moon system ...
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What are all the contributions to libration; is there a self-consistent formalism?

If I understand correctly, in a two-body system with at least one of them more-or-less tidally locked (mean rotational period = mean orbital period) if we draw a line between the centers of mass and ...
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How do the giant planets excite the orbits of asteroids?

The giant planets, particularly Jupiter, are notorious for bringing about changes in eccentricities and inclinations of smaller bodies(asteroids and KBOs). Jupiter, in fact, throws almost all the ...
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4 votes
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Probability of transit of an exoplanet in front of its star

I'm trying to calculate the probability of transit of an exoplanet in orbit around a star of diameter $d$, at a distance of $4d$ from its centre. Here's what I did: In this figure, we are only ...
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8 votes
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Which JWST instrument modes are compatible with observations of the bright trans-Earth planets Mars, Jupiter, and Saturn? Which aren't?

My comment says: ...answers to the Space SE question Can James Webb take pictures of our solar system? In what ways will they differ from/compliment those from Hubble? suggest that at some point JWST ...
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Gamma Ray Spectroscopy in detecting hydrogen

My professor explained saying that bombarding the surface with cosmic rays breaks off a few neutrons from nuclei and the nucleus, having undergone a change in energy level, emits a gamma photon. The ...
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2 votes
2 answers
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If Theia did collide with Earth, would it have produced rings? If so, would we expect to still see at least some remnants today?

Before I get into the actual question, I'll just specify two things: Few billion years ago, a planet as big as Mars named Theia, is hypothesized to have crashed into the Earth, leading to the ...
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2 votes
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Up to what distance from the Moon does the Moon's gravity hold its exosphere before it is being cast away by solar wind?

Up to how far from the Moon is the Moon's exosphere gravitationally bound to it? For the Earth's exosphere it is 120,000 mi (190,000 km) or half the Moon's distance from the Earth, beyond that the ...
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List of J₂ values for solar system bodies beyond the planets; are there any prolates?

J₂ values for the planets can be found in several sources including each planet's planetary fact sheet. Without looking I'm going to assume they are all positive (oblate) because each planet rotates ...
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Why do Venus, Earth, and Mars have tall volcanoes, but the Moon, Mercury, and Io don't?

There are numerous examples of multi-kilometre tall mountains such as Maat mons on Venus, Mauna Kea on Earth, the Tharsis volcanoes on Mars. We don't find similar such examples of volcanic edifices ...
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How does the Hubble Space Telescope measure the speed of the wind inside Jupiter's Great Red Spot?

Space.com's Jupiter's winds of change show increased storm speeds in Great Red Spot and Hubblesite.org's Hubble Shows Winds in Jupiter's Great Red Spot are Speeding Up both link to the recent open ...
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What is k2, how does it relate to Io's volcanism and how can Juno constrain its value?

This answer to Does Juno's UVS have any chance to spot Europa plumes? links to Juno OPAG REPORT by Scott Bolton, OPAG, September 2020. The slides detail past and future Juno flybys of Jupiter and some ...
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Are there any SuperCam spectra available?

A lot of pictures from the SuperCam, the NavCam or the Mastcam onboard the Perseverance rover are available online (for instance on the NASA and JPL websites). Have any SuperCam spectra been made ...
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What's the expected distribution of planet masses in a given system?

Given that the mass of a planet at a given orbital distance r is dependent on the protoplanetary material in the neighborhood of r at the time of formation (assuming no planetary migration), what ...
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3 votes
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...but where did Mars' atmosphere actually GO?

In this answer to How is space a vacuum when there are planets, gases, etc? I mention that most of Mars' original atmosphere was swept away by the solar wind after the planet lost its magnetic field ...
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Whether the comet is moving in an elliptical or hyperbolic orbit around the sun?

The time of observation after the first observation (in years), the distance between the earth and the comet (in AU) and the angle between the sun and the comet (in radians) is given. How to find ...
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1 vote
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What discoveries were made thanks to Pioneer orbiter data?

Based on the Wikipedia page Pioneer Venus Orbiter (also known as Pioneer Venus 1, Pioneer 12, 1978-051A) there were quite a few scientific instruments on board. But what scientific results were ...
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Can we learn anything from the chaotic movement of Hydra and Nix?

The NASA Visualization Explorer Moons In Chaos says Hydra and Nix, two of the moons of Pluto, show chaotic movement due to the shifting gravitational field. How long a day lasts and where the sun ...
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3 votes
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I have a question about the wording in a paper about a planetary system and comets

I was reading a paper. This is the paper: https://arxiv.org/abs/2006.01711 (https://ui.adsabs.harvard.edu/abs/2020MNRAS.496.4979D/abstract In the method section in the second paragraph there is a bit ...
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3 votes
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How massive does a moon have to be to have a stable magnetic field?

Is there a minimum mass or other minimum properties necessary for a body to have a strong, stable dynamo to create a magnetic field conducive for life? For example, would it be possible for Titan to ...
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1 vote
1 answer
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Has lunar opposition surge ever been observed from Earth? From Earth orbit?

This thorough answer to How long does lunar opposition surge last? Are there measurements of the full Moon getting suddenly brighter? details observations of lunar opposition surge by the Clementine ...
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How long does lunar opposition surge last? Are there measurements of the full Moon getting suddenly brighter?

Wikipedia's opposition surge is a short article and forwards shadow hiding and coherent backscattering as proposed mechanisms, but it doesn't really explain how much the brightness of the Moon ...
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How do they know the TNT equivalent of the meteor explosion over Vermont?

I've seen several reports of this meteor explosion, below are two. Was there infrasound recordings of the pressure wave, or were weak, local seismic signals recorded, or it this just a ballpark ...
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What is the underlying nature of the dark spot found on Uranus?

What is the nature of bright spots found on Uranus? actually quotes Space.com's Uranus Has a Dark Spot which says: During the past decade, many bright spots have been seen on Uranus in both red and ...
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What will a future cold and "dead" Jupiter look like? [duplicate]

I heard Jupiter is dying like getting smaller. For example, from Guillot et al. 2004 3: The Interior of Jupiter (also here): (Jupiter)... is still contracting at the rate of ~3 cm per year while its ...
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4 votes
1 answer
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How do pressure, temperature, and gravity affect a smaller body than Earth with the same bulk composition?

Earth has a density of about ${\rm 5.513 ~g/cm^3}$ with one Earth radius and one $g$. Venus, a very similar planet to Earth and likely with about the same bulk composition, has a density of about ${\...
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Do moons of rocky oblate planets migrate to low inclination over time? If so, does the time it takes depend on the Moon's size?

Discussions elsewhere suggest that this happens and that smaller moons would tend to low inclination with respect to the planet's equator faster than larger ones. For example, Mars' small moons are ...
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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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2 votes
1 answer
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Are ocean water planets at Mars' atmospheric pressure possible?

Can water planets exist whose atmospheric pressure at sea level is just above the triple point of water, say at about 690 Pa (0.1 psi)? If no, why not? Just curious. How thick or thin can atmospheres ...
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Gravity on Mercury's highest elevation?

This post answers what is Mars' gravity at its highest point (Olympus Mons) compared to the Earth's and Mars' standard, it's 0.3736 g (Mars standard is 0.3794 g). This also seems to be the lowest ...
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Caves traced in nine planets of solar system

Are there chances of caves being found or traced on other planets of the solar system? What's the solution? Manufacturing special telescopes for viewing or observing caves on other planets? or ...
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