Do all the planets orbit the sun at the same speed?
Nope... the further out they are, the slower they go. (And, the farther they have to travel.) It's how gravity works - the Earth moves at 66,600MPH. Mars moves at about 2/3 that speed, because the Sun's gravity is weaker there - so it doesn't have to move as fast to maintain it's orbit. Jupiter, slower still, for the same reason.
Is the pull of gravity greater than the speed of light?
Well ... the hard part of this question is comparing a "pull" to a "speed". How do we compare two completely different things to say which is "greater"? But.in general, I would say yes ... the pull of gravity is so relentless that even something traveling at the speed of light (which can only be light itself), cannot escape its effects. In other words, gravity affects light. Imagine a whirlpool in the sea, with a speedboat passing near it. As the boat passes near the whirlpool, it may pass by without problem and continue on its way, but the "pull" of the whirlpool will bend the path of the boat inward a bit. The faster the speedboat is traveling, or the further it passes from the center of the whirlpool, the less its path will bend ... but as long as it is traveling at a finite speed, the "pull" of the whirlpool will change its trajectory. Einstein's theory of relativity predicted that light would be affected by gravity in the way the speedboat's path is affected by the whirlpool. This was confirmed by Eddington in 1919, by observing how light from distant stars was measurably affected by gravity as its path passed near the sun. (This experiment had to wait until a solar eclipse in order to see these stars just off the horizon of the sun, and to measure how their apparent position was affected by the sun's gravity.) Black holes are collapsed stars so massive that light can get trapped and pulled into its center ... the way the speedboat would get trapped if the whirlpool is big enough and the speedboat passed close enough to the center. So I would say yes ... In a battle between gravity and the speed of light, gravity wins. The light may (or may not) be fast enough to escape being pulled in ... but light is not fast enough to escape the effects of gravity altogether. ---- {edit} ---- I notice that other people, like oklatonola, answered a slightly different question ... whether the pull of gravity is *faster* than the speed of light. That is certainly a reasonable interpretation of your question. This just shows that in science, the problem is often just framing the *question* precisely.
What is the force of gravity between the Sun and Earth?
The force of gravity between two objects is given by the formula[math]F=G\dfrac{Mm}{r^2}[/math]where [math]G\approx6.674\times10^{-11}\rm{Nm^2/kg^2}[/math] is the gravitational constant.For the Sun-Earth system we haveMass of the Sun, [math]M\approx2\times10^{30}\rm{kg}[/math]Mass of the Earth, [math]m\approx6\times10^{24}\rm{kg}[/math]Separation, [math]r\approx1.5\times10^{11}\rm{m}[/math]Therefore the gravitational force between the Sun and Earth is approximately[math]F\approx6.7\times10^{-11}\dfrac{12\times10^{54}}{2.25\times10^{22}}\approx3.6\times10^{22}\rm{N}[/math]Despite the notorious weakness of gravity and the large distance between the Sun and Earth, the force between them is rather substantial: it is about three thousand times the weight of all of Earth’s oceans!
Gravity: Why doesn't the Earth fall into the Sun or the Moon fall into the Earth?
The earth is constantly trying to fall into the sun, but it keeps missing. That is essentially what an orbit is. The sun exerts an attractive force on the earth, accelerating the earth directly towards the sun. This acceleration is constantly taking place. However, the earth also has some sideways momentum (perpendicular to the direction towards the sun). So as it falls towards the sun, it also moves to the side. As long as that sideways motion is enough to "side-step" the sun, the earth will orbit instead of crashing. You can see this more clearly in a more elliptical orbit:The planet (green) appears to be falling towards the sun (blue), but it has just enough sideways momentum to miss the sun and swing around. The earth and moon have an amount of sideways motion so that the orbits are nearly circular. In other words, we are moving sideways fast enough to so that we maintain a nearly constant distance to the sun, despite constantly accelerating towards it.
Does gravity affect velocity?
YES, definitely. Take the case of a freely falling body ... as it goes down, gravity tends to increase its speed. Conversely, for a body going up, gravity tends to slow it down. Hope this helps.
When you escape the earth's gravity, why aren't you pulled towards the sun by it’s gravity?
I myself wondered about this during my school days. I think when you say you are escaping earth’s gravity,you mean escaping earth’s atmosphere. When you escape earth atmosphere,you are not essentially escaping from the earth’s gravity. The moon itself is within the influence of earth’s gravity. As the sun’s gravity acts on earth,the earth’s gravity also acts on sun.But it is not as pronounced as sun’s gravity. So the effect of earth’s gravity on sun is not noticeable.You cannot escape an object’s gravity anywhere in the universe. No matter how far you go from an object, only the magnitude of the gravity decreases and it reaches zero only when we approach infinity. Even when you are in the Andromeda galaxy, you are still affected by the gravity of stars in our milky way galaxy. Thus movement of an object in space is determined by the resultant gravitational force of all the masses surrounding it.So after escaping the earth’s atmosphere, you are still within the influence of earth, moon, sun and all other planets gravity. We can ignore the gravity of stars in other galaxies as they are far away and negligible. In that scenario, only the sun’s, earth’s and moon’s gravity is more pronounced on your movement in space. You have to travel 21 million kilometres before our planet’s gravity loses out to other forces, and that’s roughly halfway to Venus.The ISS is stationed at about 400 kilometers above the earth’s surface. Even at the ISS’s orbital altitude, the Earth’s gravitational field exerts 88.8 per cent of its strength. What feels like weightlessness to those playful astronauts is actually the sensation of falling around the Earth at a high yet consistent rate of speed. Slow down the ISS and this controlled free-falling becomes just plain falling.Yes, you are pulled towards sun by sun’s gravity. But you are also pulled by the earth’s gravity along it’s orbit.The moon also pulls you towards it. Therefore,as a result of these three major gravitational pull, you travel in the direction of the resultant gravitational force with the speed proportional to the magnitude of the resultant gravitational force.So for freefalling towards sun, you have to be much closer to the sun where even the mercury’s gravity loses to sun’s gravity.
Are all the planets in our solar system moving at the same speed around the sun?
No. Orbital speed is determined by the mass of the object you are orbiting and your distance from it. All of the planets are orbiting the sun, so the mass is the same, but the distance is different. The further away they are, the slower they go. The formula (for a circular orbit - the planets actually orbit in slight ellipses, but it's close enough) is:[math]v=\sqrt{\frac{GM}{r}}[/math]Where G is the gravitational constant, M is the mass of the sun and r is the distance from the planet to the sun.To give you some examples, Mercury, the closest planet to the sun orbits at 47.9 km/s. The Earth orbits at 29.8 km/s. Neptune, the furthest planet, orbits at only 5.5 km/s.
What would happen if there was no sun? ?
Hi Skycat, The sun is more than just a familiar security blanket. In a way, it's the glue that holds our solar system together. The thought of losing our sun is terrifying. So, what would happen if our sun was gone? Here's a basic answer. The reality is a bit more complex, but this should be close enough. An orbit is just a controlled fall, including the orbit of the planets around the sun. In Earth orbit, the gravity of Earth is pulling the object down, but because it is moving forward fast enough, it falls around the curve of the Earth instead of straight down. The gravity of the Sun works the same way. Imagine the Earth was a block. a space craft is traveling parallel to one surface at a high rate of speed. Meanwhile, gravity is pulling it down towards the block, so its path is really at an angle, heading towards the block. However, by the time it reaches the plane of that side of the block, it is beyond the edge, and heading away from the block. Once again, gravity is pulling it toward the block, but its speed keeps that fall from being a straight line to the face of the block. In other words, it is falling AROUND the block. The idea of an orbit is to make sure your forward motion matches the downward motion caused by gravity. I hope that makes sense. So, the orbiting object is trying to move in a straight line, but gravity makes its path circular. If there was nothing there (like the sun), an object would continue to move in a straight line. If our sun disappeared, the planets would all fly off into space. Also I wouldn't get a sun tan. Ha Ha.