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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Planets just look like dots! Beginner telescope, hoping for some advice

I'm very new to astronomy and got myself a cheap, used 700mm 70mm diameter refractor scope and am able to see (what I think are) good images of the moon. However when I try to view planets I see ...
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Why do we care if Pluto is classified as a planet? [migrated]

Why do we care if Pluto is classified as a planet? Classification doesn't change anything fundamental about Pluto, like the orbital parameters or composition. We can't hurt an inanimate object's ...
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Abundance of penitente ice formations in the solar system

When researching for my question on extraterresitral snow, I learned about a rare snow formation called penitente which seems to be found on various (dwarf) planets, like Earth, Mars, and Pluto. ...
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If an orbit is shifting due to orbital precession, is it still a Keplerian orbit?

I was thinking about orbits a few days ago, and realized that orbits shift/precess naturally. Given that a two-body problem with a star and a planet, if the planet has an eccentric orbit that ...
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How do we differentiate between a star or planet and noise introduced due to equipment?

I understand that differentiating between celestial bodies and noise due to equipment is a fundamental problem in astronomy. I also understand that we solve this problem by looking at something called ...
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Kepler's Law, focal points - Heliocentric or Barycentric?

It is known that all the mass in the Solar system moves around the Barycenter. For the two focal points in Kepler's law; is the first focal point $F_1$ a Heliocenter? Or is it actually a Barycenter? ...
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Is it at all possible for the sun to revolve around as many barycenters as we have planets in our solar system?

Though it is understandable that the sun and the earth may be revolving around a barycenter, but, if so, not only the sun and Jupiter should also be revolving around some barycenter, the same should ...
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When (yyyy-mm-dd) does the north pole of uranus most nearly point towards the sun?

When (yyyy-mm-dd) does the north pole of uranus most nearly point towards the sun? The information I've found suggests this happened in 1944 or 1945, but would like to find a more precise date or ...
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1answer
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Where is the Solar system's barycenter located?

Where is the Solar system's barycenter located? The solar system as a whole, Where is the center of the mass for the combined mass of the Sun, inner planets, and gas giants, is it inside the Sun? Is ...
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Can moons exist inside a planet's roche limit?

Saturn's rings are inside its own Roche Limit - the limit beyond which bodies start disintegrating due to the tidal forces of the parent body. But as every rock in the ring can be regarded as a ...
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Is there convection in Mars' mantle?

Mars is differentiated, with a core, a mantle and a crust. There are no (longer any) plate tectonics on Mars. Does this mean there is no convection in the mantle? Could there be convection in the ...
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Does the earth spiral around the sun's movement/motion path?

I have watched the following video (How Earth Moves by Vsauce) regarding how earth moves: Here are some screenshots: I have some questions: Does the earth spiral ...
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How to calculate the limb darkening $\mu$ value

I am reading about limb darkening and I am very confused how to find the value of $\mu$. It states it can be found by $\mu = \cos(\gamma)$, but I am lost how $\gamma$ is found, or what it represents. ...
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How much solid matter is in the observable Universe?

I want to know the volumetric ratio of empty space to planets, stars, and all other solid matter combined. Not considering any dark matter, dark energy, or black holes. For example, you can say X ...
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Why are most discovered exoplanets heavier than Earth?

Looking at all discovered exoplanets (4393 exoplanets), I found than only 17 of them (less than one percent!) have masses less or equal to Earth's mass. Why so? Is it because it is very difficult to ...
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If Jupiter and Saturn were considered stars, which of their moons would qualify as planets by 'clearing the neighbourhood'?

Jupiter has four and Saturn seven spherical satellites. Jupiter's moon Ganymede and Saturn's Titan are larger than Mercury and they're the most massive moons at 0.0248 M♁ (Ganymede) and 0.0225 M♁ (...
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Where did the nickel in the Earth's core come from?

Why is there nickel in the core of the earth? Does it come from collisions of two neutron stars? And how did we know the core of our planet is made of nickel-iron alloy? Thank you.
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Has any moon achieved “retrograde equatorial orbit”?

There are many moons which have low (almost negligible) inclination and can be considered to rotate at the planet's equatorial plane. For instance, Galilean moons have almost negligible inclination (&...
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Minimum distance between planets

In our solar system, MOIDs (minimum orbital intersection distance) of different planets reach a minimum of ~30 million miles (Mercury and Venus). However, other star systems have more compact planets. ...
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Probability of planets in binary star systems?

There is much fiction on binary stars with planets, for whatever reason, and this keeps supporting the popular impression that those systems are frequent. Indeed, the methods for identifying ...
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Simulating oceans and ice sheets on other planets or moons?

From my friends in geosciences I learned a lot about General Circulation Models (GCMs) (for Earth's atmosphere and oceans). I also learned about ice sheet models for floating ice (like sea ice or ...
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What would be the year length of a habitable planet of 40 Eridani A?

The planet Vulcan, in Star Trek, is one of the most famous fictional planets. The length of a Vulcan year comes up in my answer at: How old was Spock in Star Trek while he was serving on the ...
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How long do thunderstorms on Venus last?

A while ago, I learned about field of exometeorology (the study of other planets ' atmospheres) which fascinates me. In particular, I read about thunderstorms on Venus, e.g. about the results from ESA'...
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Is there any “scale” for measuring salinity of extraterrestrial water?

Continuation of Is the water underneath Europa's ice cap potable? Recently, there was a question which discussed if water from Europa's ice caps is potable or not and from the answers, we ...
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What should the mass of a planet be in-order for its escape velocity to be near the speed of light? [duplicate]

What should the mass of a planet be in-order for its escape velocity to be the speed of light? Is it even possible? What will it look like from an outside viewer? Will it even be visible in the human ...
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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? [closed]

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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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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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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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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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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1answer
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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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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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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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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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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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