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The Sun and earth

The Sun's powerful magnetic forces directly affect the Earth and the rest of the solar system


Solar flares erupt near sunspots daily

Coronal Magnetic Field

Sun Spots

Solar Flares

An artist impression of the solar winds.

Winds of electrified gas rip through the solar atmosphere at nearly the speed of sound


Sun's magnetic field lines

The magnetic field facing the sun is squeezed by solar wind, while the other side of the magnetic field is swept away.

CME impact on the earth's magnetosphere.

CME impact on the earth's magnetosphere.

How the energy from a CME impact is deposited at the earth's magnetic poles.

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Sun Spots, storms, winds and flares

The surface of the Sun, or photosphere appears yellowish, corresponding to a temperature of about 5500°C. Sunspots are dark depressions on the photosphere with a typical temperature of 4000°C. However, deep in the core, the temperature can reach up to 15 000 000°C. Every second, about 700 000 000 tons of hydrogen are converted to helium at the core, with 5 million tons of matter being converted into energy. The energy takes about a million year to travel to photosphere via convection process. The Sun is not a solid body like the Earth? It's more like the planet Jupiter, rich in many types of gasses.

The solar atmosphere is permeated with magnetic fields, generated by electrified gas, or plasma, churning violently beneath the visible surface. Solar astronomers have long observed loops of plasma, called coronal loops, which appear to trace out the corona's complex magnetic-field structure, much as iron filings reveal the invisible magnetic field surrounding a magnet.

Solar Storms
Auroras, the dancing lights in the sub-polar air that fascinated our ancestors, appear when eruptions on the Sun disturb the Earth's space environment. Solar storms are more troublesome to modern technology. They can endanger astronauts and satellites, and at ground level they can disrupt communications, computers, power supplies and navigation systems.

At the speed of light, flashes of X-rays and ultraviolet rays from the Sun arrive at the Earth in 8 minutes. Hitting the atmosphere they cause disturbances in the ionosphere, which reflects radio signals. Changes in the ionosphere can interrupt short-wave radio transmissions and cause errors in navigation systems.

Also at a high speed, but following a curved path, solar protons and other energetic particles from the Sun reach the Earth in an hour or two. They can harm astronauts, damage spacecraft and if they reach the ground they can cause errors in computers.

Gusts and shocks in the solar wind due to an eruption take a few days to reach the Earth. When they arrive, they buffet the Earth's magnetic shield, the magnetosphere, causing a magnetic storm, which makes compass needles wander. The varying magnetic field can provoke damaging surges of current in long metallic structures such as power lines and pipelines. The magnetic disturbances can also dump particles from space into the upper air, where they cause auroras.
Sunspots

Sunspots are areas of intense magnetic energy, cooler and darker than the surrounding surface of the thermonuclear furnace. Sometimes the magnetic fields let loose and huge amounts of radiation and charged particles are hurled into space.

Solar flares are the biggest explosions in the Solar System

The "Solar Flare" is an explosive release of energy (both electromagnetic and charged particles) within a relatively small (but greater than earth-sized) region of the solar atmosphere.

Solar flares happen 150 million kilometres (93 million miles) away from Earth but can damage satellites and interfere with terrestrial communications and power supplies.

Solar Wind

The thermal energy of ionized coronal gas is so great that Sun's gravitational field cannot retain the gas in a confined static atmosphere. Instead, there is a continuous, near-radial, outflow of charged particles into interplanetary space, called solar wind. This highly tenuous plasma carrying mass and angular momentum away from the Sun. That flow comes to the Earth with a supersonic velocity - at about 400 km/s, but the its concentration is too low - few particles per cm3 .

Solar wind is the ongoing process of particles flowing from the surface of the Sun. The Sun's outer atmosphere continuously boils off into space, and the positive ions and negative electrons released form plasma. The wind isn't breezy like of our wind on Earth—it's more like gases emanating from the Sun's surface. As the particles reach Earth's magnetic field, they can create bits of motion and disturbances. The distance from the Sun varies, but it averages 149 million kilometers from the Earth, or 92.6 million miles. Periodically, there are bursts of increased activity, called solar flares, and even larger coronal mass ejections. These outbursts produce energetic particles that generate high levels of radiation.

Coronal Magnetic Field

The solar wind escapes primarily through coronal holes, which are found predominantly near the Sun's poles; in the equatorial plane the magnetic field lines of the Sun are more likely to close on themselves, particularly in periods of low solar activity. These closed field lines trap the hot coronal gases, leading to enhanced X-ray emissions from these hotter regions, but suppressing contributions to the solar wind.


Magnetic Storms Rip Through Earth's Magnetosphere

The Sun has magnetic poles, but unlike on Earth they are not constant. They change every 11 years or so from magnetic north to magnetic south and back. The polarity reversal happens in the middle of the 11-year cycle - a period known as the 'solar maximum' when the number of sunspots are at their peak. The last solar maximum occurred in 2000, the next solar minimum will be in 2006. The theory is that sunspots - which are often accompanied by solar flares and explosions - result from pent-up magnetic fields generated in the dynamo finally breaking through the surface.

Sun's corona
The Sun's corona can rip open and spew as much as 20 billion tons of material into space -- equivalent to the mass of 200,000 cruise ships. These explosions are known as coronal mass ejections (CMEs), the hurricanes of space weather.

Coronal mass ejections (CMEs)
When a CME ploughs into the solar wind, it can create a shock wave that accelerates particles to dangerously high energies. Behind that shock wave, the CME expands into a huge cloud that engulfs planets in its path with plasma.

The solar wind pushes and stretches Earth's protective magnetic field into a vast, comet-shaped region called the magnetosphere. The magnetosphere and Earth's atmosphere protect us from the solar wind and other solar and cosmic radiations.

Luckily for us, few CMEs are aimed at the Earth. If a CME erupts on the side of the Sun facing us, the results around Earth can be spectacular and sometimes hazardous.

At the speed of light, flashes of X-rays and ultraviolet rays from the Sun arrive at the Earth in 8 minutes. Hitting the atmosphere they cause disturbances in the ionosphere, which reflects radio signals. Changes in the ionosphere can interrupt short-wave radio transmissions and cause errors in navigation systems.

Also at a high speed, but following a curved path, solar protons and other energetic particles from the Sun reach the Earth in an hour or two. They can harm astronauts, damage spacecraft and if they reach the ground they can cause errors in computers.

Gusts and shocks in the solar wind due to an eruption take a few days to reach the Earth. When they arrive, they buffet the Earth's magnetic shield, the magnetosphere, causing a magnetic storm, which makes compass needles wander. The varying magnetic field can provoke damaging surges of current in long metallic structures such as power lines and pipelines. The magnetic disturbances can also dump particles from space into the upper air, where they cause auroras.

An average solar flare or CME releases, in two hours, enough energy to power the United States for 10,000 years.

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