SOHO real-time web watch
4 June 1999
The Solar and Heliospheric Observer (SOHO), a joint ESA/NASAspace mission, observed a large coronal mass ejection (CME) on the Sun on 1June 1999, at 19:37 Universal Time. It was first spotted by solar physicistsat the American Astronomical Society meeting in Chicago, where the SOHO datawere being displayed in real time at theESA/SOHO exhibition booth, via an internet connection to NASA's Goddard SpaceFlight Center in Maryland.The explosive event is "a real planet-buster", said Dr Richard Fisher of NASA's Goddard Space Flight Center.
"When the coronal mass ejection was observed we were not sure whether the mass ejection was moving toward the Earth or directly away from the Earth" said Paal Brekke, ESA/SOHO Deputy Project Scientist who was in charge of the SOHO exhibit.
From a preliminary investigation, the mass ejection appears to be headed directly 'away' from the Earth, a fact ascertained by physicists after a quick world-wide search for relevant images of the Sun. Normally, the SOHO team uses images of the Sun made with the Extreme Ultraviolet Imaging Telescope (EIT) aboard SOHO to determine whether events are coming or going - but EIT was shut down for routine maintenance during the CME itself.
Since the event was followed by an increase in the proton flux from the Sun it was still a possibility that the CME was heading toward the Earth. "Other types of data that could identify where the event originated were searched for both by scientists at the SOHO exhibit as well as by the SOHO team at Goddard Space Flight Center", said Brekke.
Fortunately, such data is widespread on the world-wide web. Scientists quickly downloaded solar images from NOAA's space environment centre, as well as from observatories in Austria, Australia, and Japan, to compare images from before and after the event.
"Because data are so distributed and so accessible", said DeForest, "we were able to identify and track this event from right here at the meeting. Even a few years ago, this kind of instant international collaboration would have been impossible."
The event is travelling at about 1,000 km/sec (600 miles per second) away from the Sun, according to a preliminary analysis by Dr Simon Plunkett of the Naval Research Laboratory. If it were travelling toward the Earth, it would arrive in about two and a half days and could produce a spectacular aurora at northern latitudes.
In addition solar storms can cause power blackouts, block radio communications and trigger phantom commands capable sending satellites spinning out of their proper orbits. Cellular phones, global positioning signals and spacewalking astronauts are all at risk.
Geomagnetic storms on Earth and other results of the increased solar activity are expected to reach their 11-year peak sometimes early next year at the same time as computers around the world could struggle to cope with possible problems caused by the Year 2000 (Y2K) bug. Some solar physicists have called the effects from the Sun 'the other Y2K problem'. "SOHO plays a key role in early detection of solar storms which is important for issuing warnings and forecasts of the space environment and potential impacts on Earth." adds Brekke.
Near-real-time data from SOHO is available to everyone who has access to internet. The most recent images and movies can be found at this web address: http://sohowww.estec.esa.nl/data//LATEST/index.html
