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.
763
questions
3
votes
2
answers
300
views
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 ...
4
votes
1
answer
2k
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 ...
- 16.2k
0
votes
1
answer
106
views
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 ...
1
vote
1
answer
68
views
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 ...
- 313
7
votes
4
answers
669
views
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 ...
- 17.4k
2
votes
1
answer
123
views
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 ...
- 113
4
votes
2
answers
2k
views
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 ...
- 343
24
votes
6
answers
4k
views
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 ...
- 343
4
votes
2
answers
325
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 ...
- 4,392
1
vote
0
answers
80
views
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 ...
- 113
2
votes
1
answer
73
views
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 ...
- 323
11
votes
1
answer
509
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. ...
- 4,392
2
votes
1
answer
214
views
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
...
- 185
1
vote
1
answer
225
views
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.....
- 11
17
votes
3
answers
4k
views
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 ...
- 311
3
votes
2
answers
606
views
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?
15
votes
1
answer
2k
views
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 ...
- 253
3
votes
1
answer
168
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 ...
- 33
1
vote
1
answer
190
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,...
1
vote
0
answers
31
views
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 ...
- 11
1
vote
0
answers
67
views
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 ...
- 283
3
votes
1
answer
344
views
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?
- 17.4k
2
votes
0
answers
892
views
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 ...
- 251
2
votes
0
answers
80
views
Software apps for calculating distances between planets
Are there somewhere any software apps for calculating distances between any planets in our solar system?
2
votes
0
answers
58
views
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-...
user24157
-4
votes
2
answers
2k
views
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 ...
- 187
0
votes
1
answer
965
views
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 ...
- 187
3
votes
1
answer
1k
views
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-...
- 6,613
2
votes
2
answers
1k
views
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 ...
- 21
1
vote
0
answers
68
views
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 ...
- 21
2
votes
2
answers
227
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 ...
- 375
1
vote
1
answer
113
views
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 ...
- 4,476
17
votes
1
answer
809
views
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 ...
- 1,099
-1
votes
1
answer
510
views
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 ...
user34422
1
vote
1
answer
118
views
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 ...
20
votes
2
answers
2k
views
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.....
- 4,891
4
votes
2
answers
1k
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 ...
- 311
1
vote
2
answers
357
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?
user34216
5
votes
2
answers
441
views
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 ...
- 235
5
votes
1
answer
512
views
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 ...
5
votes
2
answers
414
views
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 ...
- 53
3
votes
3
answers
645
views
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 ...
- 143
-1
votes
3
answers
656
views
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 ...
- 17
4
votes
0
answers
197
views
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 ...
5
votes
0
answers
123
views
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 ...
- 51
3
votes
1
answer
238
views
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 ...
- 17.4k
2
votes
0
answers
762
views
Identify moving object in the sky at night?
Last night in the Carribean, 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 ...
- 401
0
votes
0
answers
36
views
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 ...
10
votes
1
answer
288
views
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 ...
- 305
4
votes
1
answer
335
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:
...
