The Aurora Borealis - Northern Lights (and the southern hemisphere's Aurora Australis) are caused by the interaction of Earth's magnetic field with the flow of highly-charged particles from the Sun (known as the "solar wind"). Collisions of these particles with atmospheric molecules causes energy emission as visible light.

Auroras are normally confined to polar regions, which are nearer the magnetic poles.

When magnetic storms occur on the Sun, when electrically charged particles (ions) from the corona and solar flares are added to the solar wind produced by the corona, the charged particles are accelerated by the Earth's magnetic field interact with the gases in the upper atmosphere and cause the gas molecules to emit light. Electrons in the molecules are excited to higher energy levels and then release photons when the fall back to lower energy levels.

purplish pink color, while ionic nitrogen transforms into a brilliant blue. If an ion crashes

into oxygen in a lower altitude, it becomes the most common aurora, a yellowish-green

color. If it however, collides with oxygen at a high level, it will create the rarest blood red

aurora.

An aurora is sometimes accompanied by a crackling sound.

Auroras also occur on other planets in our solar system. According to the Geophysical Institute of the University of Alaska:

If a planet has an atmosphere and is bombarded by energetic particles, it will have an aurora. Since all planets in our solar system are embedded in the solar wind, all planets are subjected to the energetic particle bombardment, and thus all planets that have a dense enough atmosphere will have some sort of aurora

They also state that the intensity of the aurora will be dependent on the strength of the planets magnetic field.

According to NASA some of the largest auroras occur on Jupiter (which has auroras larger than the diameter of Earth) and it is unusual in that solar winds are not required as Jupiter (and its moon Io) is able to create its own charged particles and an intense electric field at it's poles.

Currently NASA believe that volcanic activity on Jupiter's moon (Io) ejects oxygen and sulphur ions (O+ and S+) into Jupiter's spinning magnetic field. It is the rotation of this magnetic field that creates the very high electrical charge at Jupiter's poles.

This interaction of the electric field and the charged particles from Io ultimately causes the majority of Jupiter's aurora.

When these particles hit the upper atmosphere, they react with the atoms and molecules of the air and cause them to glow with the characteristic colours associated with the aurora.

Produced by Collision of charged Particles from Earths Magnetsphere.

The liquid iron core present at the interior of our earth has created a magnetic field around it.Till then which has been subjected to massive bombardment with high energy solar radiation & other form of harmful cosmic rays. All these high energy charged particles are get trapped in van Allen radiation belts & in addition get reflected by the earth's magnetic field towards the pole where these particles interact with the earth's atmospheric components in form of a visible energy called the northen lights.

Jupiter is the largest planet in the solar system. Its diameter is 88,846 miles (142,984 kilometers), more than 11 times that of Earth, and about one-tenth that of the sun. It would take more than 1,000 Earths to fill up the volume of the giant planet. When viewed from Earth, Jupiter appears brighter than most stars. It is usually the second brightest planet -- after Venus. Jupiter is the fifth planet from the sun. Its mean (average) distance from the sun is about 483,780,000 miles (778,570,000 kilometers), more than five times Earth's distance. Ancient astronomers named Jupiter after the king of the Roman gods. Astronomers have studied Jupiter with telescopes based on Earth and aboard artificial satellites in orbit around Earth. In addition, the United States has sent six space probes (crewless exploratory craft) to Jupiter. Astronomers witnessed a spectacular event in July 1994, when 21 fragments of a comet named Shoemaker-Levy 9 crashed into Jupiter's atmosphere. The impacts caused tremendous explosions, some scattering debris over areas larger than the diameter of Earth. Physical features of Jupiter Jupiter is a giant ball of gas and liquid with little, if any, solid surface. Instead, the planet's surface is composed of dense red, brown, yellow, and white clouds. The clouds are arranged in light-colored areas called zones and darker regions called belts that circle the planet parallel to the equator. Orbit and rotation Jupiter travels around the sun in a slightly elliptical (oval-shaped) orbit. The planet completes one orbit in 4,333 Earth days, or almost 12 Earth years. As Jupiter orbits the sun, the planet rotates on its axis, an imaginary line through its center. The axis is tilted about 3¡. Scientists measure tilt relative to a line at a right angle to the orbital plane, an imaginary surface touching all points of the orbit. Jupiter rotates faster than any other planet. It takes 9 hours 56 minutes to spin around once on its axis, compared with 24 hours for Earth. Scientists cannot measure the rotation of the interior of the giant planet directly, so they have calculated the speed from indirect measurements. They first calculated the speed using an average of the speeds of the visible clouds that move with interior currents, except for a more rapid zone near the equator. Jupiter sends out radio waves strong enough to be picked up by radio telescopes on Earth. Scientists now measure these waves to calculate Jupiter's rotational speed. The strength of the waves varies under the influence of Jupiter's magnetic field in a pattern that repeats every 9 hours 56 minutes. Because the magnetic field originates in Jupiter's core, this variation shows how fast the plant's interior spins. Jupiter's rapid rotation makes it bulge at the equator and flatten at the poles. The planet's diameter is about 7 percent larger at the equator than at the poles. Mass and densityJupiter is heavier than any other planet. Its mass (quantity of matter) is 318 times larger than that of Earth. Although Jupiter has a large mass, it has a relatively low density. Its density averages 1.33 grams per cubic centimeter, slightly more than the density of water. The density of Jupiter is about 1/4 that of Earth. Because of Jupiter's low density, astronomers believe that the planet consists primarily of hydrogen and helium, the lightest elements. Earth, on the other hand, is made up chiefly of metals and rock. Jupiter's mix of chemical elements resembles that of the sun, rather than that of Earth. Jupiter may have a core made up of heavy elements. The core may be of about the same chemical composition as Earth, but 20 or 30 times more massive. The force of gravity at the surface of Jupiter is up to 2.4 times stronger than on Earth. Thus, an object that weighs 100 pounds on Earth would weigh as much as 240 pounds on Jupiter. The atmosphere of Jupiter is composed of about 86 percent hydrogen, 14 percent helium, and tiny amounts of methane, ammonia, phosphine, water, acetylene, ethane, germanium, and carbon monoxide. The percentage of hydrogen is based on the number of hydrogen molecules in the atmosphere, rather than on their total mass. Scientists have calculated these amounts from measurements taken with telescopes and other instruments on Earth and aboard spacecraft. These chemicals have formed colorful layers of clouds at different heights. The highest white clouds in the zones are made of crystals of frozen ammonia. Darker, lower clouds of other chemicals occur in the belts. At the lowest levels that can be seen, there are blue clouds. Astronomers had expected to detect water clouds about 44 miles (70 kilometers) below the ammonia clouds. However, none have been discovered at any level.

Jupiter's most outstanding surface feature is the Great Red Spot, a swirling mass of gas resembling a hurricane. The widest diameter of the spot is about three times that of Earth. The color of the spot usually varies from brick-red to slightly brown. Rarely, the spot fades entirely. Its color may be due to small amounts of sulfur and phosphorus in the ammonia crystals. The edge of the Great Red Spot circulates at a speed of about 225 miles (360 kilometers) per hour. The spot remains at the same distance from the equator but drifts slowly east and west. The zones, belts, and the Great Red Spot are much more stable than similar circulation systems on Earth. Since astronomers began to use telescopes to observe these features in the late 1600's, the features have changed size and brightness but have kept the same patterns. Temperature The temperature at the top of Jupiter's clouds is about -230 degrees F (-145 degrees C). Measurements made by ground instruments and spacecraft show that Jupiter's temperature increases with depth below the clouds. The temperature reaches 70 degrees F (21 degrees C) -- "room temperature" -- at a level where the atmospheric pressure is about 10 times as great as it is on Earth. Scientists speculate that if Jupiter has any form of life, the life form would reside at this level. Such life would need to be airborne, because there is no solid surface at this location on Jupiter. Scientists have discovered no evidence for life on Jupiter. Near the planet's center, the temperature is much higher. The core temperature may be about 43,000 degrees F (24,000 degrees C) -- hotter than the surface of the sun. Jupiter is still losing the heat produced when it became a planet. Most astronomers believe that the sun, the planets, and all the other bodies in the solar system formed from a spinning cloud of gas and dust. The gravitation of the gas and dust particles packed them together into dense clouds and solid chunks of material. By about 4.6 billion years ago, the material had squeezed together to form the various bodies in the solar system. The compression of material produced heat. So much heat was produced when Jupiter formed that the planet still radiates about twice as much heat into space as it receives from sunlight. Magnetic field Like Earth and many other planets, Jupiter acts like a giant magnet. The force of its magnetism extends far into space in a region surrounding the planet called its magnetic field. Jupiter's magnetic field is about 14 times as strong as Earth's, according to measurements made by spacecraft. Jupiter's magnetic field is the strongest in the solar system, except for fields associated with sunspots and other small regions on the sun's surface. Scientists do not fully understand how planets produce magnetic fields. They suspect, however, that the movement of electrically charged particles in the interior of planets generates the fields. Jupiter's field would be so much stronger than Earth's because of Jupiter's greater size and faster rotation. Jupiter's magnetic field traps electrons, protons, and other electrically charged particles in radiation belts around the planet. The particles are so powerful that they can damage instruments aboard spacecraft operating near the planet. Within a region of space called the magnetosphere, Jupiter's magnetic field acts as a shield. The field protects the planet from the solar wind, a continuous flow of charged particles from the sun. Most of these particles are electrons and protons traveling at a speed of about 310 miles (500 kilometers) per second. The field traps the charged particles in the radiation belts. The trapped particles enter the magnetosphere near the poles of the magnetic field. On the side of the planet away from the sun, the magnetosphere stretches out into an enormous magnetic tail, often called a magnetotail, that is at least 435 million miles (700 million kilometers) long. Radio waves given off by Jupiter reach radio telescopes on Earth in two forms -- bursts of radio energy and continuous radiation. Strong bursts occur when Io, the closest of Jupiter's four large moons, passes through certain regions in the planet's magnetic field. Continuous radiation comes from Jupiter's surface as well as from high-energy particles in the radiation belts.