Planets Definition and 515 Threads

TL;DR Summary: what kinds of gasses can be in the atmosphere of a planet without killing them or not being naturally possible I have been creating a fictional star system and ran into an issue, most of the planets atmospheres are not all the interesting, feels wrong to have most be oxygen...

I would like to plot the position of planets around the Sun for different dates and describe their orbits. I got the Ephemeris data for each planet from the JPL Horizons System, I got: Date__(UT)__HR:MN R.A.___(ICRF)___DEC Ang-diam ObsSub-LON ObsSub-LAT ObsEcLon ObsEcLat however...

Quite simple question. There are two planets A and B, they are 4 light years apart measured by tom on planet A. Say both A and B remain stationary. Mary flys 0.8c to tom on planet A. When she passes planet B she should see Tom or planet A 2.4 light years away, am I correct? What about tom now...

I have not seen a whole lot on this topic, so I'm just going to ask a few general questions here that have crossed my mind recently. Habitable meaning, of similar temperature to that of the Earth. 1 - What would we expect habitable planets around Brown Dwarfs to be like? 2 - What types of...

If the Sunlight lets say would go off, exactly how long would astronomers on Earth still see sunlight reflected on the surface of Mercury, Venus, Mars, the asteroids, Jupiter Saturn, etc.? I mean Sun goes dark at 0:00 from the point of view of Earth-based observers. At that exact moment, if...

Recently, I’ve heard from Anton Petrov on YouTube that some tidally-locked planets around red-dwarf stars (such as TRAPPIST-1) have been suspected to flip around their own axis every once in a while — so that the former day side becomes the night side, and vice versa. This is presumed to happen...

TL;DR Summary: Were Rahu and Ketu considered true planets in ancient times before 500 AD and is there any evidence for this in the ancient scriptures? Nowadays when people ask what Rahu and Ketu are, it is always said that those names refer to the lunar nodes. Now I thought that that...

As a retired physics professor with a long experience in complex simulation software for high energy physics experiments (e.g. the LHC) I revisited last July the n-body planetary simulations which I taught in an undergraduate physics course during the Spring 2017. It was then that the...

When we use the third Kepler law to calculate the period, distance and velocity of the Earth, we consider that the Sun is fixed. We know this is not true, because the Sun is also attracted by the Earth. I was wondering, how could we use Kepler laws to calculate the period, distance and velocity...

I assume that planets and their satellites are created more or less at the same time. Why gaseous planets like Saturn have solid rings and satellites?

I am of the total understanding that most astrophotography pictures are not a real representation of what objects actually look like... I guess I mean, it is not an accurate representation of what things would look like if you were actually the same distance closer as the picture's magnification...

Got interested on how plants (and other things such as fungi) could evolve on other planets along with how plant life may flourish depending on the position of the planet to the sun, moon etc. I'm looking for any article talking about this or something similar.

Do all the planets in all the solar systems in our Galaxy spin in the same direction ? Clockwise or anti clockwise depending on the viewers POV.

Will there be a compression of matter that the planet is made out of due to gravity when we are talking about planets? If so I would like to know what the effect would be in the example given in the summary.

Relevant formulae:- Angular velocity in uniform circular motion ##=## ##\omega## ##=## ##\frac {2\pi} t##, where ##t## is the time taken to complete one revolution. Centripetal acceleration in uniform circular motion ##=## ##a## ##=## ##\omega^2r##, where ##r## is the radius of the circular...

Can someone please verify if my reasoning is accurate? I chose E) Planets B and D because they both have the same ratio of mass to radius which is the lowest of all the other planet options. Due to the fact that they have mass and radius evened out the gravitational pull will pull weight down...

So far, I have found g of the foreign planet, Vf of the ball, and realize that GPEiA = KEfA (Am I right here?). Thus, since GPEiA = GPEiE, GPEiE also equals KEfE. I also understand that, since the same impulse is applied to catch the objects, both objects have the same momentum at the moment...

Hello. If its possible I'd like to find out more about tidal locking for planets orbiting K type dwarf stars. Specifically, at what distances from their host stars would exoplanets have to be to avoid becoming tidally locked. I'm specifying K dwarves because, from what I've read (see...

I'm designing a growth chart for my granddaughter with the planets on it. I wanted them to be proportional* as far as distance goes - with the sun at the floor and Pluto at, say, six feet, but obviously that's impossible since all the inner planets would be in the first inch or two from the...

Could someone please tell me if I'm on the right track with understanding this. The periods of the comet and Uranus is different because of Kepler's second law? Is it because planets orbit the sun in a circular path whereas for comets it's a highly elliptical orbit? Thank you.

I was recently looking at a comic reprinting of Retro Sci Fi Tales # 9, and the synopsis on the site spoke about a story of the "Exposition Universelle", where at a fictitious worlds fair in Paris in 1878, they unveil a "grand inter-galactic telescope so powerful that it can view the surfaces of...

Let G be a graph where vertices are heavy planets and edges are forces between the incident vertices. A complete graph K6 of six planets (of different masses) has 15 edges, why don't the planets collapse to the center?

Hello, I am recently studying communication in curved spacetime. For example, if i use a laser in 1000nm and the initial beam waist is 1m. Then the rayleigh range is ##3 \times 10^6m##. The nearest distance between Earth and Mars is about 5500km. So the beam waist at the Mars will be around ##2...

I was reading this (which is notable for its non-science content, but I am only referring to this part): https://www.nationalreview.com/2020/11/wokeists-assault-space-exploration Is there a matrix that shows the amount that goes between the planets? (And here, I consider a moon to be a "planet".)

In every single question asking about the maximum height you get from jumping in 2 different planets they consider that the speed you leave the ground is constant. Why is that? Speed would be constant if impulse were constant. Impulse would be constant if both force and time were constants...

Ok, I know there are a lot of strange things in our solar system. Can anyone explain why the small planets spin so slowly? and why does Jupiter spin so quickly? It seems like a ball of debris, getting smaller and smaller, would increase its speed like an ice-skater pulling their arms in...

Would it be in any way physically possible for a binary star system to evaporate / explode, leaving behind two spheres of a solid metal such as gold (or an alloy), which were then rigid enough to drift together and maintain their shapes, rather than just collapsing into a larger sphere? And...

How scientists calculated the weight of Mars to be 6.39 × 10^23 kg?

Ok, so I have long been fascinated with magnetic fields and their mysterious nature. I've been wondering what would happen when the magnetic field of Earth gets bent/disturbed/rippled by some extraneous force. I am aware the extent of effects that magnetic fields have on a planet is great, but I...

Why is it that all of the planets in our solar system (to our knowledge) orbit the sun in such a way that they all go around the sun in roughly similar orbital planes? Why don’t we have planets with orbital planes at significantly different angles?

Astrophysicist Scott Manley determined the energy required to destroy a planet (2.25 x 1032 joules). Is the energy required to destroy 3 planets simply a case of multiplying his result by three? If not, how much energy would it take to destroy 3 planets? This scenario relates to Incredible Hulks...

I was thinking to myself, if it were ask to me why is the orbit of planets elliptic, how to justify?: The bould phrases i just know to justify with collected dates. IS this a reasonable justification?

I was reading this: http://www.physics-astronomy.com/2020/04/set-your-alarm-jupiter-venus-and-moon.html It seems that for this to happen the Moon would need to be in-between the pair of planets and the Sun - but the Sun's path defines the Ecliptic, and the bright planets are all very close to...

The HR 8799 star is 129 light-years away from us, in this image we can see thermal emissions coming from these planets. Do these emissions move at the speed of light? If so does it mean that what we are seeing in this image is how the planets looked like in infrared 129 years in the past?

We send a lot of rovers to Mars, as interesting as the planet could possibly be. But why are we not putting satellite grids around other planets that could transmit superficial probe data at the very least? That along with whatever other prospects satellite grids could possibly bear us. That...

We can not see planets or stars during the day time because of the scattering of the sunlight. But, in space, all planets and stars would be visible. Consider the situation that a rocket is going to space during the day time. At what altitude these stars or planets would become visible? On...

"Astronomers have spotted an ultrafast star [S5-HVS1], traveling at a blistering 6 million km/h, that was ejected by the supermassive black hole at the heart at the Milky Way five million years ago." -- https://www.sciencedaily.com/releases/2019/11/191112110238.htm If this star had planets 5...

I've been thinking about this from time to time, I'll try to make this short and understandable. So we go back to the early universe within our current best model of extrapolation called the Big bang theory. In the early universe as it was expanding we have a very dense and energetic matter...

I have a planetary system with planets orbitting a central star (circular orbits). I want to shoot a projectile P in a straight line from planet A to B and need to calculate the angle or vector to shoot the projectile P. I know the straight line of the projectile is physically not correct, but...

Why are planets visible in telescope in daylight? As far as I understand both 1) total light flux from the planet 2) and that from the atmosphere receved by scope are proportional to the aperture area. So why then we can see the planets? And I have realted question. I am my city humidity and...

If Jupiter is made of gas, how can it maintain its spherical shape without being contained in a spherical shaped container?

My current understanding is that a person falling toward the surface of a planet with no atmosphere, would feel no force acting upon themselves even though they are accelerating relative to the planet. If the mass of the planet suddenly tripled while the person is in free fall, would the person...

Centrifuges have long been viewed as the means to provide artificial gravity in the zero-g of deep space. Space colony structures like the O'Neill cylinder and the Stanford torus. Centrifuges could also work their magic on the surfaces of low-gravity planets. Conical or paraboloidal shaped...

Is there a possibility that there are stars and planets that are composed entirely of DM? How would we detect such stars or planets? Well, I am not sure about stars, as the definition of a star depends on its fuel that it uses, I guess.

I'm working on a novel and the action has moved off Earth and into the asteroid belt. I've been using a few websites and apps - notably AstroGrav, Stellarium, and Atlas InfoGraphics - to figure out where objects are in the solar system at the future date of the novel. But I can't find a way to...

Is it difficult to show that planets follow elliptic orbits around the sun, using Newton's theory? I have seen the equations showing it, but from General Relativity, considering the Newtonian limit. How to arrive at them using only Newton?

Hi! I have a question about escape velocity. If a planet is bigger and have a greater escape velocity than another planet. Do this effect the density of the bigger planet in any way? Or do we have to know the mass of the bigger planet to know if the density is larger or lower for this planet?

Some or all of the planets are thought to have migrated long ago under the gravitational influence of Jupiter. Would the trojan matter at their L4 and L5 points have followed during their migration to new orbits? In other words, while the L4 and L5 points are approaching or receding from the...

Homework Statement In a distant galaxy, a planet orbits its sun at a distance of m with a period of 108 s. A second planet orbits the same sun at a distance of m. What is the period of the second planet? Select one: a. s b. s c. s d. s e. Homework Equations T^2=constant * r^3 The...