![]() ![]() Webb’s new view revealed Fomalhaut’s two inner belts for the first time, which didn’t appear in previous images taken by the Hubble Space Telescope or other observatories. But the Webb researchers weren’t expecting to see three nested rings of dust extending out 14 billion miles (23 billion kilometers) from the star - or 150 times the distance of Earth from the sun. The dusty disk around Fomalhaut was initially discovered in 1983 using NASA’s Infrared Astronomical Satellite. The space observatory focused on the warm dust that encircles Fomalhaut, a young, bright star located 25 light-years from Earth in the Piscis Austrinus constellation. Solar system objects can not hit us at larger speed.Astronomers used the James Webb Space Telescope to observe the first asteroid belt seen outside of our solar system and unveiled some cosmic surprises along the way. The resulting maximum velocity at impact is 83.1 km/s. So, to arrive at the speed at impact we have to add Earth's escape velocity (11.2 km/s) to the above derived velocity. This, however, does not equate to the speed at impact, as the gravitational attraction to Earth accelerates the object towards impact. If at closest approach the object moves in opposite direction to Earth, collision will be head-on and one has to add both speeds to get the total speed. It follows that Earth orbits Sun at a speed of 29.8 km/s. This escape velocity, the velocity required to escape from a location along Earth's orbit around Sun, equates to a marathon (a wee bit more than 42 km) per second. Equating the centripetal force required to keep Earth in this orbit to the gravitational force exerted by Sun, it follows that Earth orbits Sun with a kinetic energy equal to half the energy needed to escape Sun.Īn object that orbits Sun along an extremely elongated elliptical path and reaches closest approach to Sun somewhere along Earth's path, has at that point (perihelion) a kinetic energy equal to the energy needed to escape from Sun.Īs kinetic energy scales quadratically with speed, it follows that Earth's speed along it's orbit around Sun equals $\frac12\sqrt2$ times the local escape velocity. What is the maximum speed at which suchĮarth's orbit around Sun is very close to circular. As the person asking seems keen to get a larger variety of responses, I am going to give this question another twist by enquiring about the maximum speed relative to Earth:Įarth is a planet, which means it cleans its orbit around Sunįrom material objects. This question has received some excellent responses. In fact, comet ISON was moving so quickly last November when it approached perihelion that had a) you been able to see the comet in daylight and b) Coment ISON not met an untimely demise you would have actually seen it change position in the sky (relative to background starts) by the hour. The most extreme examples are sun-grazing comets, which have very close approaches to the Sun. As these comets approach perihelion (the close approach to the Sun) Kepler's Second Law tells us that thevelocity of the satellite increases. Some comets even have eccentricities greater than one, which means they're on one-time hyperbolic orbits around the sun. ![]() Compared to planets, most comets tend to have eccentricities very close to 1 (which means their orbits are very elliptical). Now let's look at interlopers to our solar system, like comets. You can see a clear relationship between velocity, and distance away from the sun. Just look at this graph below, taken from. ![]() So as you move away from the sun, your period increases more than your distance, which means your orbital velocity is decreasing. If planet $B$ travels in and orbit, with a semi-major axis of $4a$ then the period has now increased by a factor of 8, even though the semimajor axis (and approximately the circumference, if the orbit has an eccentricity close to 0) only increased by a factor of 4. V_\text$$ So using the equation above, let's say planet $A$ travels in some orbit around the sun, and the semi-major axis has a length of $a$. The maximum speed of an object that orbits the Sun at a certain distance $r$ is known as the escape velocity: ![]()
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