# Tag Info

6

I concur with everyone else here (of course) that the gravity at the "surface" of Jupiter is entirely determined by the mass contained within that surface. The composition makes no difference. However I differ with some on the answer to the headline title question. We simply do not know whether Jupiter has a rocky core. A popular theory for the formation ...

4

According to Newton's Law of Universal Gravitation, you simply need interacting masses in order to generate a gravitational force between them. Gases have mass and they therefore can contribute to gravity. So even if Jupiter is entirely gaseous, it is so incredibly massive besides (so much gas!), that it has a much stronger gravitational pull than Earth. ...

3

Gravity does not have polarity, it only attracts. An analogy with magnetic or electric fields is appealing (because they are all field forces, decay with the square of the distance, etc...) but science is not made of analogies, it is made of observations. And no one has observed gravity repulsion. Gravity is in fact much much weaker than the electric force ...

9

Comet Shoemaker–Levy 9 crashed into Jupiter a few years back. As well as these molecules, emission from heavy atoms such as iron, magnesium and silicon was detected, with abundances consistent with what would be found in a cometary nucleus. Those heavy elements are consistent with the comet being at least being partially composed of rock. So Jupiter ...

5

It doesn't matter if the body is made of gas, rocks, liquid or plasma, the four states of matter all have mass. So, as we know, mass create a gravitational field, and the more mass the stronger the gravity - and Jupiter has 317x Earth mass.

1

Most stars are of a solar-mass or below. The average number of companions that each stars has (in the sense of being part of binary or higher multiple systems) systems ranges from 0.75 for stars of a solar mass to approximately 0.35 (not a well-established number) for the more numerous M-dwarfs. Let's take a compromise value, say 0.5. The separation ...

0

What is far apart? In the universe there are zillions upon zillions of stars, some of them small that live fast and die young.In lamens terms so to speak,they burn all of their fuel at a very fast rate. While large stars burn much slower there are many different ways in which they react to each other, some stars are in binary form. They become dependent upon ...

0

Binary stars are not very far apart. Which begs the question, how did they get so close together, if most star systems are quite far apart.

2

The actual answer has nothing at all to do with the temperature. Even low-mass stars would form black holes if they ran out of nuclear fuel to burn, and simply cooled whilst being supported by "standard" gas pressure in their centres. That is because that gas pressure would be proportional to the temperature, but the star is able to cool so it would need ...

1

Most of the universe is pretty empty in terms of the density you're used to in daily life. It's perhaps not that stars are far apart, but that they are pretty compact. This is because baryonic matter (as opposed to dark matter) can lose energy via electromagnetic radiation and hence condense to smaller and denser objects. This is only opposed by angular ...

0

Whether an object is a black hole is not just determined by its mass. It's determined by whether that mass is entirely within its Schwarzschild radius. In principle, any object can be a black hole if all its mass is concentrated into a sufficiently small volume. For example, the Sun's Schwarzschild radius is about 3.0 km -- but its actual radius is about ...

-2

The Stars are far apart because the Universe has been expanding for billions of years at a fast rate of speed. So since the Stars have been moving away from one another for so long it is only natural that the Stars are so far apart.

0

A supernova may actually be necessary in the creation of a stellar black hole. At the ends of their lives the cores of massive stars are made mostly of iron-peak nuclei from which you cannot extract more fusion energy. To support their weight, these stars rely on electron degeneracy pressure - the pressure caused by the Pauli exclusion principle allowing no ...

1

The dwarf planet Haumea two equatorial diameters, it is triaxial. The longest equatorial diameter is about twice the length of the polar diameter. According to Google and Wikipedia, the most oblate star is Achernar which has an equatorial diameter 56% larger than the polar diameter due to it rapid spin. The discussion at ...

0

If you're only interested in objects devoid of non-microscopic empty spaces, then we're pretty much into the realm of stars, planets, and asteroids. Objects of this type larger than $\sim100$km are all nearly spherical, simply because of the effect of their own gravity (the spherical shape minimises the gravitational energy). However, small asteroids can ...

4

Saturn is the most oblate planet in the solar system. If the equatorial diameter is $a$ and the polar diameter is $b$ then its oblateness, $(a-b)/a = 0.1$. We do not know the oblateness values for more than one or two exoplanets and even these are somewhat uncertain, but are thought to be lower than Saturn's value. For example ...

1

I think it is going to depend on the type of object being examined. Planetary objects tend to be more spherical than stars, which in turn tend to be more spherical than galaxies. My vote goes toward the Heliospheric current sheet, which is thought to extend 10-20 astronomical units (about 1.5x10^9km to 3x10^10km) from the Sun, and is thought to be about ...

1

You must apply Newton's law $$m\frac{\mathrm{d}\boldsymbol{v}}{\mathrm{d}t} = \boldsymbol{F}$$ which related the force $\boldsymbol{F}$ to the acceleration (=change of velocity). Note that positions, velocities, and forces are all vector quantities. Also note that as the objects move (change position), their mutual forces change (both direction and ...

1

The first experiment that proved Einstein's theory of general relativity was the bending of light around our sun. So if the sun can effect our measurement, in this case the light from a star behind the sun, a black hole sure can. Secondly, gravitational lensing is observed by galaxy clusters where multiple images of a background galaxy are formed around the ...

0

I have a theory about this and she is new, she explains quantum phenomena, but is in Portuguese. this here => http://forum.intonses.com.br/viewtopic.php?f=77&t=147809 And here => http://forum.intonses.com.br/viewtopic.php?f=77&t=287255

2

The Schwarzschild black hole is the simplest, being just an isolated, nonrotated, uncharged black hole. If $\tau$ is the proper time measured by a clock moving along an arbitrary path in this spacetime, then in Schwarzschild coordinates -\mathrm{d}\tau^2 = -\left(1-\frac{R}{r}\right)\mathrm{d}t^2 + \left(1-\frac{R}{r}\right)^{-1}\mathrm{d}r^2 + ...

1

Normal case: The effect would not be very noticeable unless the large planet was extremely large / high gravity (e.g. it would look "almost" normal) looking at one another. If the planet was that large, it would probably not be able to support life, but to see what would happen, lets assume it can support life. Relativistic case, from the large planet, ...

2

Technically, the distance between Sun and Earth changes throughout the year. The Earth moves around the Sun on an elliptical orbit. It's distance from the Sun changes between 152m km (aphelion) and 147m km (perihelion), a difference of 5 million kilometres, twice per year.

4

While the Sun and Earth attract each other, they cannot fall into each other because of angular momentum conservation. In a central field (where the force is acts in the direction of the distance vector and depends on distance only), the specific angular momentum vector $\boldsymbol{L}=\boldsymbol{r}\times\boldsymbol{v}$ is conserved ($\boldsymbol{r}$ is ...

4

This is a bit of a speculative question, but I can answer it. Dark matter has been observed in galaxies, and the distributions of dark matter in galaxies have also been measured. It seems clear that the matter is firmly in our universe - we just can't detect it with electromagnetic radiation. *However, there are ideas (extremely speculative) that dark ...

2

"in a spherically symmetric distribution of matter, a particle feels no force at all from the material at greater radii, and the material at smaller radii gives exactly the force which one would get if all the material was concentrated at the central point". This may be poorly worded. The idea is not that the distance from the center of the body must be ...

1

The original result is Newton's shell theorem. Since we can break up a spherically symmetric distribution into spherically symmetric concentric shells, it is sufficient to consider the corresponding statement for one such shell: for each shell taken individually, there is no force on a particle inside, and a force on a particle outside as if all of the mass ...

5

As HDE 226868 noted in his answer, the Sun is not going to go supernova. That's something only large stars experience at the end of their main sequence life. Our Sun is a dwarf star. It's not big enough to do that. It will instead expand to be a red giant when it burns out the hydrogen at the very core of the Sun. It will continue burning hydrogen as a red ...

6

The Sun does not have nearly enough mass to become a supernova. Instead, it will swell to become a red giant, enveloping Mercury, Venus, and possibly Earth. After that, it will shed its outer layers as a planetary nebula, and settle down to become a white dwarf. Wikipedia, apparently, says the exact same things I had though of: The Sun does not have ...

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