# Tag Info

### Why are there so many objects perfectly orbiting each other? Isn't it infinitely more likely that two random objects crash/fly apart?

Your intuition that two isolated objects approaching each other and not already in a closed orbit will either collide or will fly apart again is substantially correct. If the objects are not already ...

### Why are there so many objects perfectly orbiting each other? Isn't it infinitely more likely that two random objects crash/fly apart?

Btw, here's an expertly drawn diagram that took 1000 hours in MS Paint to show things visually. None of your three pictures really illustrates the actual physical scenario very well. (OK, picture B ...

### Why are there so many objects perfectly orbiting each other? Isn't it infinitely more likely that two random objects crash/fly apart?

they can either miss each other and fly apart (if the velocity is enough and there's not enough gravitational attraction between them), or they can be attracted enough to each other that they ...

### Can the Schwarzschild orbit equation be solved exactly?

Closed-form analytic solutions for bound timelike geodesics around a Schwarzschild black hole were first (to the best of my knowledge) given by Charles G. Darwin (grandson of) in 1959 in this paper (...

### Why are there so many objects perfectly orbiting each other? Isn't it infinitely more likely that two random objects crash/fly apart?

Partly it's about how galaxies form (see another excellent answer about that). But do also consider that you're seeing the survivor bias of 13.8 billion years. If they weren't in a stable orbit, the ...
Accepted

### Meaning of a Constant in the Unbound Orbit Equation

Your equation is close to the standard form, rewrite it with $\delta$ of zero, and $\alpha$ and $\beta$ as $a$ and $b$. Here is a figure from Wikipedia (Hyperbola article): The distance $MF_1$ is ...

### Is Each Day the Same Duration?

Yes, the solar day length varies from 24 hours - ~22 seconds to 24 hours + ~30 seconds. Here's a graph for 2022, computed for apparent solar noon at Greenwich, using data from JPL Horizons The ...

### Why are there so many objects perfectly orbiting each other? Isn't it infinitely more likely that two random objects crash/fly apart?

chausies asked: "Why are there so many objects perfectly orbiting each other?" Apart from the fact that most orbits are not perfectly circular but more or less elliptical: if two objects ...
Accepted

### Why is the time from vernal and autumnal equinox different than from the autumnal to the vernal one?

as I think the paths are symmetrical parts of the elliptical orbit of the earth No, they are not symmetrical in the way you think. Perihelion and aphelion are separated by exactly $180°$ (by ...

### Escape velocity work done problem

to provide velocity to send to infinite distance from gravitational pull of earth so for that we have to apply external force This is called an “initial velocity”. The problem begins at the “initial ...

### HW: particle subject to central force with exponential logarithmic orbit

Well, you know the trajectory to be a logarithmic spiral, and you have figured out the relation between the time $t$ and angle $\theta$. At the starting position, $t=0$ and $\theta=0$. If you look ...

### What is the motivation for supposing a pendulum exhibits circular motion?

I am aware that the central tenant of circular motion is that there is a centripetal force acting radially inward that takes on the form $$F = \frac{mv^2}{r}$$ and that the velocity along this path is ...

### Why are there so many objects perfectly orbiting each other? Isn't it infinitely more likely that two random objects crash/fly apart?

And yet there are a zillion celestial objects perfectly orbit each other This is survivorship bias. Based on our current model of how we think planets form, there were many orders of magnitude ...

### How does the Dzhanibekov Effect change if replaced with a propeller?

A T-handle has three distinct mass moment of inertia values (indicated below in red, green and blue directions) As you notice, about the z-axis (blue) the MMOI value of $47\;{\rm kg}\,{\rm mm}^2$ is ...