Ison comet survived its passage near the Sun - Le Figaro

comet Ison was a big scare astronomers who followed closely its closest approach to the Sun in the evening on Thursday. Two hours after he approached a little over a million kilometers of the surface of our star, a very close distance, since it is less than one solar diameter, Ison has not recurred in the field of two Soho and Stereo probes observing the solar neighborhood. Close this passage is made unprecedented rate, which reached 1.4 million km / h! The initial findings were that big ball of ice and came from outer solar system dust had not survived the thousands of degrees as it passes and had disintegrated. A tragic outcome that some astronomers had predicted, but has withdrawn any chance to observe the comet in the night sky at the beginning of December, to the naked eye in the best case, and if twin.

This morning ISON reappeared as a bright spot Photo credits:. ESA / NASA / SOHO

But this morning, surprise, a bright spot has reappeared on the images of Soho, exactly where the path Ison was expected. “We could not see a very small tail, which seemed to come from the remains of comet dust, and then, little by little, a brilliant condensation reappeared on the images,” says Dominique Bockelée-Morvan, astronomer and director of Research at the CNRS at the Observatoire de Paris. This “brilliant condensation” is a sign of renewed activity of the comet nucleus, or what remains is fragmented if that starts to emit gases and dust being heated by the Sun.

It is still too early to say if the comet is intact or fragmented, and what proportion of its original mass has been preserved, but it is in any case sufficient material to form a ring with a visible activity. It will also explain why Ison remained invisible for a long period after its closest approach to the Sun. One hypothesis is that the temperature was so high that dust were directly burned and vaporized, leaving no any material capable of scattering light and make visible the comet. The kernel itself is invisible because it is very dark and should be a little less than a kilometer in diameter. Away enough, the temperature had come down enough so that dust can survive.