# Tag Info

0

The example you give is <1 kg, <1 meter. Gravity waves move the whole earth (>10^24 kg) by a relative small distance (>10^-18). The product of that is well over a million times bigger.

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Gravity acts on all matter, not just water (it just so happens that water flows with less resistance than rock) which is why we get noticeable water tides but not very noticeable earth tides. However, if you were to bring a very large gravitating body too close to earth, you would find that the earth isn't quite as solid as it feels. The answer to your ...

3

The gravitation of the stars in our galaxy keep the solar system in it. I'm not sure whether that's important for earth or for life on earth though, but it makes for nicer night skies. Gamma ray bursts, if close enough and (im)properly oriented, affect earth. A gamma ray event from a "soft gamma repeater", SGR 1900+14, is known to have affected earth's ...

1

The distant stars are also responsible for cosmic rays, which in turn can affect the Earth's weather

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Machs principle, that inertia is caused by the distribution of distant stars was a principle that Einstein tried to incorporate into GR, but failed. However Barbour, quite recently incorporated an aspect of Machs principle into his theorising of time: ephemeris time An ephemeris gives the position of celestial bodies, and duration is deduced in terms of ...

7

The stars in our galactic neighbourhood do have a dynamical, gravitational effect on the inner workings of the solar system: They built the Oort cloud The Oort cloud is a roughly spherical cloud of icy bodies that is thought to act as a reservoir of long-period comets (and which we speculate exists to explain said comets' existence). These icy bodies ...

6

The other answers talk about some of the effects. This is a complementary answer that attempts to put a number to the force behind one of the effects - gravitational attraction. Proxima Centuri is the closest star to our solar system. It is about 4 × 1016 m away and has a mass of 2.45 × 1029 kg. The mass of Earth is about 5.97 × 1024 kg. Plugging these ...

3

Gravitationally, there is little immediate effect on earth on a daily basis, though over very long periods of time, stars that pass near enough to the sun could disrupt the orbits of Oort cloud objects and send them towards the sun (and earth or other planets in our Solar System). Culturally, stars have a very big impact on our species. Religion, art, ...

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A lot (to put it mildly) of elements are created in stars and supernovae. These elements then travel through space until they fall to Earth (or, to be exact, some microscopic portion of them reach us). Earth itself wouldn't exist if stars hadn't generated elements which then clumped into dust, into minerals, and so on until a big ball of matter started to ...

6

I don't think that light from the stars other than Sun is of much practical use nowadays except for the classic navigation, where it's essential of course. I guess any effect comes from the limitless reach of the gravitational force, which drops with the square of the distance but grows linearly with the mass exerting the force. A star most obviously ...

3

I worked this out a little while back in order to check something said on one of these Nova or other science show specials. I wanted to know how much energy would be required to remove the entire atmosphere of the Earth and whether a supernova (or other astronomical event) could possibly do this. Earth's Atmosphere Let's assume the following quantities: ...

3

How long time does it take before three planets achieve the same relative position? The answer is never, except for the case when their orbital periods can be expressed with low integers, like the 4:2:1 resonance of Io, Europa and Ganymede However, what you are asking about is when they are going to be in almost the same position again, a quazi-period. To ...

2

Meteors are essentially bits of rock that are independently in orbit around the Sun and which cross the Earth's orbit. If the Earth happens to be there at the same time then it will enter the Earth's atmosphere and we will see a meteor. The velocity of meteors is related to how fast they we going in their orbit around the Sun, combined with how fast the ...

2

All speed is relative. But an object that starts from rest at infinity will reach a velocity of about 11 km/s when it hits Earth, if Earth is the only thing pulling on it. At the same time, Earth is moving with an orbital speed of about 30 km/s. Their relative importance will depend on the direction from which the meteor is approaching - but on the whole ...

5

Plenty of others made it clear that babies aren't made out of matter from somewhere else. But if the earth's mass were to increase ten percent by magic, its orbit would not change. Its momentum—its tendency to fly off into space in a straight line—would increase by ten percent, and the counteracting force of the sun's gravity would increase by ten percent. ...

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As others have said, the mass of the Earth doesn't go up because we are eating food produced on Earth. Suppose we somehow were importing really large amounts of extra-terrestrial food, now what happens? We roast. Food contains a fair amount of carbon. Carbon from extra-terrestrial food is just as much a greenhouse problem as burning fossil fuels. ...

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Mass is conserved (up to whatever small contribution nuclear decay has to the overall loss of mass). All biological matter is just created from materials from the environment (we do eat, right?). With exception of an occasional space probe, shooting stars and solar wind effects, the earth can be considered a closed system in terms of matter exchange. ...

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Life forms are made up from materials already present in Earth. Thus, increasing population would not alter the overall mass of the planet, and can't impact its orbit.

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If the super nova happens in any system it is not safe if you in it. As far a a blast radius You take the class of star to a habitable planet can differ. You would die of radiation poisoning if the Earth survived. The sun is around 150,000,000,000 meters, 1,368 W/m2, 1.7×1017 J from Earth. A super giant star is around 2,100 times bigger than the sun. So ...

-1

According to Phil Plait and others, anything over 100 light years (and probably a fair bit closer) should be safe. There aren't any known supernova candidates that close. http://earthsky.org/space/supernove-distance https://twitter.com/BadAstronomer/status/201708339904778240 SN 1987A isn't even in our galaxy. It's over 150,000 light years distant.

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So this is really really easy and I don't know why the top answer doesn't explain what's going on. I have a lamp on my desk, which is opposite the headboard of my bed. Sometimes I lie there reading with the lamp on to illuminate the room, but with my lowered vantage point, oh no, a first world problem hits - there's a bright light in my field of vision ...

0

According to wikipedia the orbital period of Planet 9 is 10,000–20,000 years. This means it would take a minimum of 5,000 years to switch between perihelion and aphelion. So - even our best historical observation data of kuiper belt objects is just a tiny fraction of the time it takes for Planet 9 to move in it's orbit. There's not really sufficient ...

2

Is this the correct procedure? Do I not need to recalculate the centre-of-mass position/velocity after each time step? I've made a big mistake somewhere; the planets are very unstable and either move in a line or spiral inwards! This is probably down to the stability of your numerical system and not the center of mass of the Sun. (Which by the way is a ...

1

It's a combination of a few things. Firstly when we are looking for exo-planets we know we are not going to observe them based on their luminoscity, therefore we use different techniques based on how the exo planet will effect the light we observe from their sun. This method works brilliantly if the star and exoplanet are in relatively close proximity but ...

5

Pretty simple reason really. We only see exoplanets under extremely lucky circumstances. So we are only seeing a tiny tiny fraction of all exoplanets. If for example we are only seeing 0.1% of all exoplanets in each star system we look at, that is a HECK of a lot worse than the 8 out of 9 in our own star system.

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The reason why we can see exoplanets 13,000 light years away but not a planet 200 AU away (about 30 light-hours) is because these planets are found using different techniques. The planet discussed in the article I linked was discovered using a technique known as "microlensing," which requires a star to pass behind another star with a planet around it. The ...

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The problem with finding a new planet in our solar system is not that it is too faint, but knowing where to look in a big, big sky. This putative planet 9 is likely to be in the range 20-28th magnitude. This is faint (especially at the faint end), but certainly not out of reach of today's big telescopes. I understand that various parts of the sky are ...

6

We haven't detected planets millions of light years away. Right now the most distant is less than 20,000 light years away. Even for the planets we have detected, they are for the most part not "seen" or imaged directly. Instead they are found by the effect they have on the parent star (usually gravitational wobble or transit detection). In both cases, ...

3

Think of a star as a big globe with ideal gas inside. Gravity acts as a force compressing the globe, the more it compress, the more energy goes to thermal part since $$dE = TdS-PdV$$ so a shrinking volume decreases $PdV$ term ($P$ is negative in this case, otherwise the system would be expanding), and for $dE=0$ because no reactions are occurring and no ...

3

If at any time the speed of the planet in the reference frame of the star exceeds the escape velocity $\sqrt{2GM_\star/r}$, where $M_\star$ is the mass of the star and $r$ is the distance from the star to the planet, it will escape in a hyperbolic trajectory (or straight line if $M_\star\rightarrow0$). As noted in the other answers, the result of the ...

3

I believe what he's pointing out is that energetic particles have sufficient kinetic energy to counter the pull of gravity, but as the star cools, the net kinetic energy decreases until the particles cannot go "up," or away from the centroid of mass. At that point, the star's mass collapses inward. The total mass is probably less than before, since the ...

4

The scenario you suggest is of course hypothetical, but in all cases you must conserve angular momentum and mass/energy. So for example: If you have a way of removing mass from a star in such a way that the mass disappears outside the orbit of the planets (in astrophysics this is accomplished simply by mass loss - either the star has a wind that expels mass ...

1

Your final question very much correlates with a famous thought experiment.If the Sun was suddenly removed the planet s will still continue to stay in orbit. For 8 minutes and 20 seconds. This is because the speed of the space time fabric or simply putting gravity travels at the speed of light. That is, the earth will be devoid of sunlight and will move ...

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A coarse correction would have to be made because of the difference in the curvature of space in that section of space when a planet is deleted. The sun holds the planets in orbit and they would fly away as if the string to a tether ball was cut to all the planets.

2

The motion of a comet can be understood in terms of a couple of principles. First - Inertia. Newton's first law states that an object will remain at rest or in uniform straight line motion unless acted upon by an external force In other words - assuming that "something" had given a comet a velocity, it will keep going unless something changes that. ...

1

I've got to chime in on this one for reasons of discussion only, because I can think of two reasons why this would not happen. Collisions are usually depicted as a center mass to center mass action. when we think of the earth and moon, it's thought to be slightly off center. yet, there can be a 'collision' when two bodies enter each others gravitational ...

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