BBC:
Comet
Lovejoy
dove deep into the Sun's atmosphere in 2011 and surprised
astronomers when it emerged from the other side (before then
disintegrating). Images of the event have provided astronomers
with an unprecedented look at the magnetic field within the
Sun's corona. Lovejoy approached the Sun at 600 km/s and
experienced megakelvin temperatures. Astronomers using NASA's
Solar Dynamics
Observatory
and Japan's
Hinode
spacecraft observed that the comet's tail didn't follow
the normal trajectory away from the head. Instead it got locked
into a different path by the solar magnetic field and moved
back and forth as the field fluctuated. The magnetic field's
fluctuations are one of the sources of solar winds and flares,
and the chance to observe its behavior in the corona is a rare
one. No instruments that scientists could create would be able
to survive long enough to provide any data from inside the
corona. Each sun-grazing comet like
Lovejoyâmdash;1600 have been observed, but
Lovejoy was the first to reappearâmdash;serves
as an indirect way of studying the corona. The next is expected
by the end of 2013.
