A team of solar physicists has put its reputation on the line by predicting the exact shape of the Sun鈥檚 corona during Thursday鈥檚 eclipse.
If they get it right, it will be good news for space weather forecasters who are desperate for an accurate model of the Sun鈥檚 magnetic behaviour.
The moon will eclipse the sun in a path across Southern Africa on 21 June, making it possible to see the charged particles of the solar corona. Zoran Mikic and colleagues from the Space Applications International Corporation (SAIC) in San Diego say their computer model of the corona can predict its shape up to five days in advance. The model鈥檚 input data are measurements of the Sun鈥檚 magnetic field strength made at Kitt Peak Observatory in Arizona.
Advertisement
The team struggled during a previous test in 1999, because the corona鈥檚 magnetic fields were changing too fast for their model. At the time, the Sun was approaching the maximum activity of its 11-year solar cycle.
The sun is now at the peak of that cycle, the solar maximum. 鈥淪ome of their past predictions have been very good, but probably this one won鈥檛 be right,鈥� says Jim Klimchuk who studies the solar corona at the Naval Research Laboratory in Washington DC.
Solar flare
At solar maximum, Klimchuk says there鈥檚 a reasonable chance the sun will be releasing a coronal mass ejection during the eclipse. These are 100,000 kilometre long ejections of material that sometimes lead to magnetic storms when they hit Earth.
Mikic recently improved the resolution of his model to 1000 km, much smaller than the size of a CME, so he鈥檚 confident he can capture the way they affect the corona鈥檚 shape.
The trouble is, the mechanism of magnetic reconnection that powers the release of CME probably happens on a much smaller scale of somewhere between a few 100 and 1000 km. So if CME is just starting to erupt during the eclipse, Mikic鈥檚 model won鈥檛 predict it.
But Mikic鈥檚 colleague, Roberto Lionello, says he thinks they will pull it off despite the difficulties: 鈥淲e鈥檙e pretty confident鈥�.
Web link: