Questions tagged [planet]

Questions on astronomical objects orbiting a star massive enough to be rounded, not massive enough to cause fusion, and which have cleared its orbit of planetesimals.

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1answer
92 views

How would Earth's magnetic field change if the outer core was solid?

A widely accepted theory for how the Earth's magnetic field is generated is the dynamo theory. Dynamo theory describes how molten magma convection currents containing metal are locally spun the same ...
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How does a planet-sized robot standing on a planet affect its gravity?

I originally asked this at the sci-fi exchange but was told it was off-topic as it was about real-world science. Here is a picture of Unicron standing on top of the planet Cybertron, as written by ...
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Do planets have effect on velocity of Earth?

There is method for finding extrasolar planets called Transit-timing variation. If I understood correctly, exoplanets accelerate or decelerate each other (according on their position), so we can ...
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What was the definition of a planet before August 24, 2006?

In 2006, the IAU produced a definition of what it is to be a planet. This definition famously excludes Pluto, to the disarray of this small body's fans. Before this decision, what was the definition ...
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1answer
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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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What are the correct positions or alignment of planets in relation to each other and the Sun, is it vertical center, baseline or completely random

From a lot a illustrations and videos, the planets seem to align in vertical center to each other like this: Is this really true? I like to imagine that the planets are actually in weird alignment to ...
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5answers
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What makes protoplanetary disks start rotating? (Initial energy needed to rotate)

Planets form from a protoplanetary disk that has been rotating around its star. The initial energy that makes them rotate really matters to me. Why did the protoplanetary disk start rotating around ...
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1answer
41 views

What celestial body (inside the solar system) has the highest flattening ratio?

As a planet, Saturn has the highest flattening(ellipticity) which is 0.09796. So, it makes Saturn with the largest equatorial bulge as a planet and as such Saturn is the flattest planet. However, I ...
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Positions of planets before Christ?

All the solar system simulations I've come across showing the positions of planets only show the positions in a certain time period, at beginning of the first millenium the earliest. There was just ...
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1answer
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Why would a planet form a cometlike tail under conditions of weaker rather than stronger solar wind?

This question is prompted by one posted on the worldbuilding stack exchange: https://worldbuilding.stackexchange.com/questions/189701/could-this-planets-tail-be-visible I understand that the ionized ...
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1answer
153 views

Why has Saturn stopped contracting gravitationally?

The following text is from here: The jovian planets get their heat from the Sun and from their interiors. Jupiter creates a lot of internal heat and releases this heat by emitting thermal radiation. ...
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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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Photographing Mars, Jupiter and Saturn

I want to take pictures of planets, well at least Mars, Jupiter and Saturn with some surface details. I have a Canon EOS 7D Mark-II and a Tameron 150 - 600mm lens (very heavy), a 1.7X extender, and a.....
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Do celestial objects need to be big to have liquid water on their surfaces?

I mean no asteroid, planetoid that I am aware of has water on its surface. It is way more common to see ice in it. So I figured that the size of the celestial body has something to do with the cycle ...
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How do we weigh a planet?

How do we weigh a planet? My friend asked me how do scientists weigh a planet. He is not from science background so I need to make him understand with simple analogy. How can I explain to him?
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1answer
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Is there a name for a planet and its moons/satellites?

I'm wondering if there's a name that encapsulates the concept of a planet and the objects that orbit in its gravity. There's a solar system that encapsulates a star and its multiple planets and other ...
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1answer
90 views

Is there a possibility of finding a system where a star is orbiting a planet?

Is it possible for a star to orbit a planet IF the planet is bigger than the said star? Or is it possible even if the star is bigger than the planet and still the star is orbiting the planet? I have ...
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1answer
143 views

What is this planet or satellite in this picture?

I took this photo in Shijiazhuang, Hebei Province, China, 38°13'N 115°18'E (+38.23, +115.31) on the night of February 8, 2020. Here you can see a round object above the moon, and it was moving fast,...
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How can I see planets with my telescope? [duplicate]

I have bought a Celestron Astromaster 130 telescope and I am relatively new to astronomy, when I tried to view Jupiter a few months ago I could not make out any details. It was just a white orb. Any ...
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Is there a useful measure of how “life-dominated” a planet is?

If life exists on Mars or Venus, then in contrast to life on Earth, it must be "just scraping by". I can imagine a few ways to quantify this: Life on Mars or Venus is hard to detect -- any ...
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1answer
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Are all the planets differentiated?

The Earth is differentiated, as it has a distinguishable core, mantle and crust with different compositions and densities. Are all the other planets differentiated as well?
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How to find the temperature of a planet accounting for the atmosphere?

Recently, I started writing a program to generate star systems, and I need a formula to find the approximate surface temperature of a planet. I know of several formulas for this, for example this one ...
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Software apps for calculating distances between planets

Are there somewhere any software apps for calculating distances between any planets in our solar system?
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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-...
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Have Earth, Mars and Jupiter and Neptune not cleared their orbits of space debris? [closed]

According National Geographic's Space Encyclopedia (p68, column 3) written and illustrated by David A Aguilar Pluto has not cleared its orbit of space debris but neither have Earth, Mars, Jupiter and ...
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What is the average temperature of all planets at 1 bar?

Jupiter's (and Saturn's) "surface" temperature is defined as that at 1 bar. It is inconsistent to say the other planet's surface is their hard surface. Applying the same measure what is the ...
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1answer
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Is it possible to have a trinary star system with a planet that orbits their barycenter?

I am trying to model a 3-star system with a planet. The three stars have the same mass. I have gotten the stars (Yellow, Pink, Blue) into a stable orbit. However, I am wondering if a "free-...
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How to calculate the orbital period and the density of a planetary body?

I'm a student studying in 9th grade, I am making this fictional habitable planet named "Darwin B" for a planet making competition. It orbits a sun-like star at a distance of 1.15 AU or 172 ...
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Spotted fast, VERY bright, moving object in the sky tonight in Gex, France [duplicate]

Tonight around midnight, I spotted a very bright moving object in the sky. Confused and intrigued with my sighting, I decided to go on google to find some answers. It clearly was not a plane as it was ...
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2answers
162 views

If the Sun's trajectory were altered, would the solar system follow?

I was reading a text state that the sun is not stationary: "it orbits the Galactic center once approximately every 226 million years as the galaxy spins which is also traveling through space ...
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1answer
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Could a near collision with small black hole account for the effects of the 9th planet?

Much interest has been raised about the existence of a 9th planet. One reason for this is the strange orbits of bodies in the outer solar system. Could the orbits be explained by a near collision of a ...
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Can the paper narrowing Solar System's barycentre to within 100m help find Planet Nine?

I've just read this recent news article, Astronomers Have Located The Centre of The Solar System to Within 100 Metres, reporting on a paper[1] that claims narrowing the Solar System barycentre to ...
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If I know apparent planetary positions how do I calculate the date?

I have planetary position in retrograde how do I calculate the date? For eg, I know Mars was in retrograde in Scorpion (Sidereal 210 to 240 deg), how do I calculate the date and year of this? As of ...
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Hypothetical planet jump: Will it perturb star systems?

In a more speculative corner of SE somebody was dreaming up a story of planets traveling between star systems through wormholes. I was wondering how much the appearing/disappearing of a planet the ...
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Why is there so little nitrogen in the Martian and Venusian atmospheres?

Why don't our neighbors have much nitrogen? You would think that, without 'nitrogen-fixing' organisms and such, there might be more.....
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2answers
306 views

What is the minimum mass of a celestial object so that it can have a moon?

I was wondering how massive something have to be so that it it can attract moons by pop culture standards (ellipsoid/round shape). Could a planetoid have a moon? What is the relation between the mass ...
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223 views

Can a star turn into a planet?

I have read in a magazine that a star can actually form back to a planet... is it true?! Does it mean all the planets in our galaxy can be revived back to what they were before?
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Keplerian Elements for Approximate Positions of the Major Planets

Simple question here. I am working on something that needs to compute an orbital path using Keplerian Elements. When doing some research I came across this JPL page: Click Here. Within that link is a ...
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1answer
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Can tidally locked planets have liquid oceans on their night side, and would such a planet be habitable?

Let's say we have a tidally locked planet orbiting a star. And let's say that the conditions on its surface are just right for water to exist on its surface. Conventional wisdom says that the water on ...
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When was the concept of rogue planets first theorized?

So after watching the Kurzgesagt video about life on rogue planets I became fascinated by the concept. I did some digging, and the earliest reference to the concept I could find was Philip Wylie's ...
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Is it ever possible to see Earth's shadow on other planets?

Is it ever possible to see Earth's shadow on other planets? How would the shadow present, and what would be the magnification, equipment, or other conditions necessary to see it? Is there any way of ...
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What would happen to the Earth if the orbit of another planet in the Solar System was disrupted by a cataclysmic collision with a large body?

There's plenty of speculation about what would happen if a large asteroid collided with the Earth itself, but less about the effect on Earth of a large asteroid or even a moon or minor planet ...
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Help identifying a very slow-moving object during meteor shower photography

I just wonder if anyone could shed any light on this puzzle. Two nights ago whilst I was out photographing the Lyrids meteor shower from the UK something else showed up on my images when I checked ...
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How quickly do planetary rings form?

Just a very general question, but I haven't seen this discussed elsewhere. If a moon gets busted up for some reason, say a collision with another moon, and is at the right orbital distance from its ...
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1answer
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Is there any thing special with an axial tilt of roughly 25°?

Half of the planets in the solar system have an axial tilt of $25.5\pm 3^\circ$: earth (23.5°), mars (25.3°), saturn (26.7°) and neptune (28.3°). If random collisions in the early solar system caused ...
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Identify moving object in the sky at night?

So last night I was looking at the sky at about 8PM EST, and I noticed this really tiny object moving pretty fast from left to right, just between the two stars in the photo. It's very difficult to ...
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What was that single file line formation of flashing plane lights flying in the sky at night? [duplicate]

It was here on the west coast at 5 am pacific standard time when I went outside for a smoke when out of the corner of my eye what looks like a plane with flashing lights going across the sky when all ...
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1answer
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Determining the area of Lagrange Points

I have looked into Lagrange points a decent amount and I see many images that show the L4 and L5 locations as wide sweeping areas. Jupiter's Trojan asteroids are a good example of this. As well, L3 ...
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254 views

Definition of Rotation versus Revolution

Let there be a planet for which the duration of a solar day is equal to a year around the sun such that: ...
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Calculating the position angle of the moon (the rolling back and forth)

I have been watching the the NASA Moon Phases Video of the year 2020. Pretty much everything makes sense and I know how to calculate it including the moon phases, declination, azimuth, apogee and ...

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