Tuesday, April 24, 2007

Get Your 3D Glasses to View Our Sun in 3D!

NASA released on the Web the first 3D pictures of our sun, but in order to see them you’ll need to wear 3D glasses.

And it’s not only the spectacular view of a blue or green sun that might interest you. NASA says the new images, provided by two spacecrafts orbiting Earth, can also help scientists discover how to effectively predict the famous solar flares that disrupt GPS satellites, cell-phone communications, computers and cars.

A solar flare is a violent explosion in the Sun's atmosphere with an energy equivalent to a billion megatons, traveling normally at about 1 million km per hour (about 0.05% the speed of light), though sometimes much faster. Solar flares take place in the solar corona and chromosphere, causing geomagnetic storms in Earth's magnetosphere. But they can also affect the astronauts onboard the ISS.

According to NASA, the images were obtained using the twin Solar Terrestrial Relations Observatory, or STEREO, satellites that can create more accurate, real-time views of these powerful solar events.

NASA launched the STEREO spacecrafts back in October 2006 and they are now orbiting the sun, one slightly ahead of Earth and one slightly behind. The difference in their trajectory, just like the distance between our two eyes, provides the depth perception that allows the 3D images to be obtained.

"The first reaction was 'Great, the instruments work,' but beyond that the first reaction was 'Wow!'" scientist Simon Plunkett said as he explained the images to a room full of journalists and scientists wearing 3D glasses.

One other mystery scientists hope to solve using the images which are now displayed on the Internet and museums and science centers across the US is related to a special type of solar eruption called coronal mass ejection. A coronal mass ejection (CME) is an ejection of material from the solar corona, usually observed with a white-light coronagraph. The ejected material is a plasma consisting primarily of electrons and protons (in addition to small quantities of heavier elements such as helium, oxygen, and iron), plus the entrained coronal magnetic field.

When the ejecta reaches the Earth as an ICME (Interplanetary CME), it may disrupt the Earth's magnetosphere, compressing it on the dayside and extending the nightside tail. When the magnetosphere reconnects on the nightside, it creates trillions of watts of power which is directed back towards the Earth's upper atmosphere. This process can cause particularly strong aurora also known as the Northern Lights (in the Northern Hemisphere) and the Southern Lights (in the Southern Hemisphere). CME events, along with solar flares, can disrupt radio transmissions, cause power outages (blackouts), and cause damage to satellites and electrical transmission lines.

“Coronal mass ejections you might think of as analogous to hurricanes here on Earth,” said STEREO project scientist Michael Kaiser of NASA's Goddard Space Flight Center, in Greenbelt, Md.

“We are trying to do the same thing with these coronal mass ejections,” Kaiser said. However, things are not that simple because the spacecraft that plays the role of the observer sits right in front of the Sun.

“It’s almost like somebody blowing a smoke ring at you from across the room and trying to predict how fast it’s moving,” Kaiser told SPACE.com. “What you need is somebody on either side of the room looking at that same smoke ring and they can triangulate on it.”

Scientists would like to improve predictions of the arrival time from the current day or so to a few hours, said Russell Howard, principal investigator for the Naval Research Laboratory project.

STEREO program scientist Madhulika Guhathakurta said scientists have until now been "modeling in the dark" when it came to predicting solar storms. The twin spacecraft give researchers the vantage point to "provide the observations needed to validate the models."

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