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Solar flares are tremendous explosions on the surface of the Sun. A solar flare occurs when magnetic energy that has built up in the solar atmosphere is suddenly released. Radiation is emitted across virtually the entire electromagnetic spectrum, from radio waves at the long wavelength end, through optical emission to x-rays and gamma rays at the short wavelength end. The amount of energy released is the equivalent of millions of 100-megaton hydrogen bombs exploding at the same time! The first solar flare recorded in astronomical literature was on September 1, 1859. Two scientists, Richard C. Carrington and Richard Hodgson, were independently observing sunspots at the time, when they viewed a large flare in white light.
In a matter of just a few minutes solar flares heat material to many millions of degrees and release as much energy as a billion megatons of TNT. They occur near sunspots, usually along the dividing line (neutral line) between areas of oppositely directed magnetic fields.
Flares release energy in many forms - electro-magnetic (Gamma rays and X-rays), energetic particles (protons and electrons), and mass flows. Flares are characterized by their brightness in X-rays (X-Ray flux).
Solar flares extend out to the layer of the Sun called the corona. The corona is the outermost atmosphere of the Sun, consisting of highly rarefied gas. This gas normally has a temperature of a few million degrees Kelvin. Inside a flare, the temperature typically reaches 10 or 20 million degrees Kelvin, and can be as high as 100 million degrees Kelvin. The corona is visible in soft x-rays, as in the above image. Notice that the corona is not uniformly bright, but is concentrated around the solar equator in loop-shaped features. These bright loops are located within and connect areas of strong magnetic field called active regions. Sunspots are located within these active regions. Solar flares occur in active regions.
The frequency of flares coincides with the Sun’s eleven year cycle. When the solar cycle is at a minimum, active regions are small and rare and few solar flares are detected. These increase in number as the Sun approaches the maximum part of its cycle.
The key to understanding and predicting solar flares is the structure of the magnetic field around sunspots. If this structure becomes twisted and sheared then magnetic field lines can cross and reconnect with the explosive release of energy. In the image to the left the blue lines represent the neutral lines between areas of oppositely directed magnetic fields. Normally the magnetic field would loop directly across these lines from positive (outward pointing magnetic field) to negative (inward pointing magnetic field ) regions. The small line segments show the strength and direction of the magnetic field.
A person cannot view a solar flare by simply staring at the Sun. Flares are in fact difficult to see against the bright emission from the photosphere. Instead, specialized scientific instruments are used to detect the radiation signatures emitted during a flare. The radio and optical emissions from flares can be observed with telescopes on the Earth. Energetic emissions such as x-rays and gamma rays require telescopes located in space, since these emissions do not penetrate the Earth’s atmosphere.
Why stydy solar flares?
Solar flares have a direct effect on the Earth’s atmosphere.
NASA fired three microsatellites into space over the Pacific Ocean Wednesday morning to study the earth’s magnetic fields. The 55-pound ST5 satellites were carried aloft from Vandenberg Air Force Base aboard a Lockheed L-1011 jet. Shortly after 6 a.m., when the plane reached 39,000 feet, a compact Pegasus rocket dropped from the aircraft’s belly, fired its engine and ferried the satellites on a 10-minute climb into space.
The mission’s goal is to demonstrate the benefits of a group of small, low-cost satellites simultaneously measuring the earth’s magnetic fields from different locations.
Microsatellites are of unusually low weights and small sizes. One reason for miniaturizing satellites is to reduce the cost: heavier satellites require larger rockets of greater cost to finance; smaller and lighter satellites require smaller and cheaper launch vehicles and can sometimes be launched in multiples. They can also be launched ‘piggyback’, using excess capacity on larger launch vehicles. Miniaturized satellites allow for cheaper designs as well as ease of mass production, although few satellites of any size other than ‘communications constellations’ where dozens of satellites are used to cover the globe, have been mass produced in practice.
Besides the cost issue, the main rationale for the use of miniaturized satellites is the opportunity to enable missions that a larger satellite could not accomplish, such as:
· Constellations for low data rate communications
· Using formations to gather data from multiple points
· In-orbit inspection of larger satellites.
NASA unveils plans for one of the largest rockets ever built to take a manned mission to the far side of the moon. It will ferry a mother ship and lunar lander into Earth orbit to link up with a smaller rocket carrying the crew. Once united they will head for the moon where the larger ship will remain in orbit after launching the lunar lander and crew.
The far side — so called because it always faces away from the Earth — was first photographed in 1959 by a Russian probe. In 1968 the astronauts of Apollo 8 became the first to view it directly.
Some missions will also see manned spacecraft landing in unexplored areas such as the lunar mountains and on the moon’s south and north poles.
Funding has been forthcoming and design work has begun to send men back to the moon.
The centerpiece of the stack is Crew Exploration Vehicle (CEV).It will be bigger, able to carry four astronauts comfortably and six a bit more snugly—twice the load of the three-man Apollos.
For another thing, it will be equipped with solar panels, a sensible addition in a sun-drenched place like the inner solar system—and one that reduces the demands on fuel cells and batteries. It will also be able to either splash down in the water as the Apollos did or thump down under a parachute on dry desert. Finally, modern composite materials and computers will improve on the ungainly weight and clanking brain of the older ships.
The new lunar lander will be similarly improved, with updated electronics and materials. It too will be a larger ship than its predecessor, big enough to carry all four astronauts down to the surface while the mother ship idles empty in lunar orbit.
Two new rockets—both adapted from shuttle engines—will get all this hardware into space. The larger of the two will loft the lunar lander and other equipment into Earth orbit. A second, smaller rocket will follow, carrying the CEV. The crew vehicle and the lander will then link up and fly off to the moon.
One selling point of the CEV is its versatility. If the spacecraft is ready by its 2011 starting point and the moon trips indeed don’t start until 2018, that means seven years of downtime. Astronauts could fill part of that gap flying shakedown trips to the International Space Station. After the U.S.’s moon presence is re-established, the CEV could become a central player in eventual Mars missions. "The spacecraft would have to evolve for the different demands of a Mars flight, particularly the higher re-entry speed," admits Horowitz. The basic design, however, would remain the same.
NASA officials have decided to delay the space shuttle Discovery’s launch from May until at least July 1 while engineers replace four fuel-level sensors in the shuttle’s external tank.
These fuel sensors are responsible for making sure the shuttle’s main engines shut down at the precise speed needed to get the astronauts in orbit and on course. One of the four sensors has been reading slightly low.
Dust samples from a comet formed in deep space unexpectedly contain high-temperature mineral particles that may have been ejected by the young sun at the dawn of the solar system, scientists said Monday.
First-sample results from NASA’s Stardust mission suggest that scientists may have to modify the traditional view that comets are bodies of ice and dust composed largely of interstellar material on the outskirts of the solar system.
Instead, the sun, in a process not yet fully understood, may have catapulted material outward even as the "dust disk" that formed the solar system was swirling inward like a whirlpool with the sun at its center. "We have found fire and ice," Brownlee told reporters at the Johnson Space Center here.
Early analysis revealed minerals that included magnesium iron silicate, known as olivine, or, in its gem-quality variety, peridot; magnesium aluminum oxide, also called spinel; and titanium nitride. All these form at temperatures of at least 2,000 degrees Fahrenheit.
The orbiting Cassini spacecraft has spotted what appear to be water geysers on one of Saturn’s icy moons, raising the tantalizing possibility that the celestial object harbors life.
Scientists generally agree several ingredients are needed for life to emerge, including water in liquid form and a stable heat source. But so far, the evidence of any large amounts of water in liquid form on celestial objects beyond Earth is circumstantial and indirect, based on scientists’ analysis of rocks and other data.
If Enceladus does harbor life, it probably consists of microbes or other primitive organisms capable of living in extreme conditions, scientists say.
The Great Red Spot that has dominated the planet Jupiter’s cloudtops for hundreds of years now has a companion and it is nicknamed "Red Jr" and officially named Oval BA. It was first observed in 2000, when three smaller spots collided and merged. It is about half the size of the Great Red Spot and almost exactly the same colour.
At first, Oval BA remained white - the same colour as the storms that combined to create it. But over the past few months, it has started to change in appearance.
No one is quite sure why the Great Red Spot is red.
One theory is that the storm dredges material from deep beneath Jupiter’s cloudtops and lifts it to high altitudes. Here, ultraviolet rays from the Sun turn colour-changing compounds (or chromophores) red.
Oval BA may have strengthened enough to do the same, scientists say.
The European Space Agency’s SMART-1 spacecraft — now circling the moon — is headed for a planned early September impact with Earth’s celestial neighbor.
SMART-1 is Europe’s first robotic lunar mission. The name SMART stands for Small Mission for Advanced Research in Technology
The spacecraft was launched on Sept. 27, 2003. Making use of its ion propulsion engine to slowly nudge it outward from Earth, the probe powered its way into lunar orbit on Nov. 15, 2004.
Outfitted with miniaturized instruments, SMART-1’s goal has been to gauge key chemical elements in the lunar surface, as well as look into the theory that the moon was formed following the violent collision of a smaller planet with Earth long ago.
Observatories around the world have indicated interest in watching the outcome from SMART-1’s collision with the moon.
At impact, the ESA spacecraft will weigh a little more than 628 pounds (285 kilograms), punching the moon at a grazing incidence near 37 degrees south latitude. The near-side impact is timed so that it will be illuminated to assist in observations from Earth.
Scientists said methane in the atmosphere of Saturn’s moon, Titan, originated in a methane-rich water ice that forms a crust above an ocean of liquid water mixed with ammonia. Major episodes of outgassing pumped methane into Titan’s mostly nitrogen atmosphere three times during the moon’s evolutionary history.
Mo'nonymous on New companion of Nep...
Mo'nonymous on New companion of Nep...
Mo'nonymous on New companion of Nep...
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