what causes the northern lights,what bis it exactly and where does it occur?
146984
Northern lights originate from our sun. During large explosions and flares, huge quantities of solar particles are thrown out of the sun and into deep space. These plasma clouds travel through space with speeds varying from 300 to 1000 kilometers per second. \n\nBut even with such speeds (over a million kilometer per hour), it takes these plasma clouds two to three days to reach our planet. When they are closing in on Earth, they are captured by Earth's magnetic field (the magnetosphere) and guided towards Earth's two magnetic poles; the geomagnetic south pole and the geomagnetic north pole.\n\n\n\nOn their way down towards the geomagnetic poles, the solar particles are stopped by Earth's atmosphere, which acts as an effective shield against these deadly particles.\n\nWhen the solar particles are stopped by the atmosphere, they collide with the atmospheric gases present, and the collision energy between the solar particle and the gas molecule is emitted as a photon - a light particle. And when you have many such collisions, you have an aurora - lights that may seem to move across the sky. \n\nIn order for an observer to actually see the aurora with the naked eye, about a 100 million photons are required.\n\n\nFor more info :-\nhttp://www.northern-lights.no/english/what/cause.shtml
961074
snow isn't really white its just the amount of light that is bounced back so when it melt it changes states of matter and becomes a liquid which bounces back light differently
908551
The aurora borealis is an atmospheric phenomenon. \n\nThe sun's Solar wind contains a lot of electrons and other charged particules which then hit atoms in the upper atmosphere. The collision energises the atoms and causes electrons in the atoms to shift energy levels, and release energy as light. \n\nThe colours you see are due primarily to solar wind particles energising oxygen and nitrogen atoms.
108762
There is a common misconception that winter happens when earth is farthest from the sun.  Actually, earth's orbit is only slightly elliptical.  Temperatures vary because of the inclination of the earth.\n\nThe hours of daylight and darkness are not related to earth's orbit.  The hours change because the earth rotates about the north pole - south pole axis and this axis is tilted relative to the sun.  Check the link in sources for all the details!
169563
The earth's magnetic field is generated by the molten core deep inside the planet.  The magnetic North pole is positioend in the North of Canada (Churchill Bay) I believe, and this is due to an iron rich element of the magma core being near the surface.  \n\nThe magnetic North Pole is moving, and there is eveidence to show that this is quite normal over time, and that at points in history the poles have reversed.
14526
The bright ring is called a 'halo'\n\nIt's a fairly common sight and occurs when high thin clouds containing millions of tiny ice crystals cover much of the sky. Each ice crystal acts like a miniature lens. Because most of the crystals have a similar elongated hexagonal shape, light entering one crystal face and exiting through the opposing face refracts 22 degrees, which corresponds to the radius of the Moon Halo.\n\nSee a nice picture of one here:\nhttp://antwrp.gsfc.nasa.gov/apod/ap000515.html
78877
The "white" is caused because snow has a great many tiny interfaces, called "phase boundaries," where air (a gas phase) meets ice (a solid phase). Every time light encounters a phase transition, it is defracted. If you've ever looked at a stick submerged partially, you've seen this--a straight stick will look like it has a bend in it right at the water's surface. Well, with snow, the tiny ice crystals, and the many small bubbles in ice (water is a bent and polar molecule, so when it freezes, it expands, making small bubbles inside), and the places where individual ice crystals begin and end--all of this scatters light all around. This makes it so that a big bunch of snow will look white. If you look at a single snowflake under a microscope, though, you will see that the crystals individally are clear.\n\nWhen it melts, there is only one phase transition, right at the surface. The light is defracted a bit, but only once--it doesn't scatter light all around like snow does.\n\nBut it can! If you've ever seen a big fountain, where the water is splashing and tumbling about, it will also look white due to phase transition. Likewise, if you make a whole bunch of tiny bubbles under water, you can scatter light and make it look white.
244426
The blue sky phenomenon is caused by Rayleigh scattering of sunlight through the atmosphere.  The scattering is strongly polarized at 90 degrees from the direction of the sun.  The light is polarized tangentially with respect to the sun.
1118148
It's actually called an "aurora". An aurora results from the emission of light radiation after magnetospheric particles collide with atmospheric molecules. \n\nIn more general terms, there are a series of invisible belts that surround Earth called Van Allen Belts. These belts are trapped within the magnetosphere and thus trap magnetospheric particles. However, around the northern and southern pole some of the particles escape and come in contact with the atmosphere. As a result, a light show occurs.\n\nThe Northern Lights are scientifically known as Aurora Borealis\nThe Southern Lights are scientifically known as Aurora Australis
975410
Aurora are generate by charged particles captured by the terrestrial magnetic field impacting atoms in the upper atmosphere and generating flourescence.  They constantly shift shape and color as the magnetic fields shift around and the particle flux changes. As such, asking how long an aurora lasts is akin to asking how long a cloud  in a hurricane lasts; the question itself is too vague to answer with confidence.
1036628
If you mean the earth having a magnetic field, then the main way is that it takes fatal amounts of solar radiation and deflects it around our planet and off into space.  If you live far north or far south you can see the solar particles being deflected.  It's called aurora or the northern/southern lights.
61059
Solar rays, that always come to earth.  U r able to see them becuase of ur position in earth, North Pole.\nBut the lights are just solar rays.
547692
I've seen the Aurora Borealis on a few occasions but always on a small scale covering just a part of the sky - mostly in Scotland.\n\nI'd love to go the the Arctic or Antarctic (Corona Borealis) and see it at it's best with the whole sky illuminated, that would be amazing.
817297
Northern Lights. It was breathtaking.
481798
A Corona.\n\nThe moon can produce interesting optical effects when conditions are right. The most common of which are moon rings, moon bows, which are similar to rainbows, moon dogs and moon pillars. A rainbow is produced when sunlight is refracted through water droplets - A similar effect is produced when moon light refracts through ice crystals\n\nThe ring around the Moon is caused by the refraction of Moonlight (which of course is reflected sunlight) from ice crystals in the upper atmosphere. The shape of the ice crystals results in a focusing of the light into a ring. Since the ice crystals typically have the same shape, namely a hexagonal shape, the Moon ring is almost always the same size.
638657
An aurora means in English: dawn. There are specific places to see some of them, like the Aurora Borealis, that can be seen only close to the north pole. Why ? Nobody knows.
411859
Its rare, but it can lightening when it snows