Comet 67P Churyumov–Gerasimenko, accompanied by the European probe Rosetta has reached its “perihelion”, the point in its orbit that is closest to the sun.
The comet reached this point at 4:00, Central European Time & 2:00 GMT.
This was the moment it reached a distance of 186 million kilometers from the sun, before moving away following the long elliptic curve of its six-and-a-half year orbit.
The European Space Agency will outline its first conclusions live at 13:00 GMT (15:00 Central European Time) on a Google Hangout.
Everyone is invited to send questions using the hashtag #AskRosetta
Pherihelion to reveal more about the birth of our galaxy
Scientists are keen to study organic particles that have been trapped inside Chury for 4.6 billion years. They are hoping that as the comet nears the sun, gasses will expand due to the increasing heat and cause an explosion of matter. They believe this could provide clues to the formation of the solar system.
As it gets closer to the sun, ice from the surface of the comet turns into steam, triggering gas and dust storms and projecting particles.
The European space robot Philae, which is on the surface of the comet, has been offline in radio silence for more than a month but the Rosetta orbiter will be able to catch these particles. It is currently located about 300 km from the comet but cannot get any closer without the risk of getting lost in the gas storm.
Rosetta’s instruments can catch particles even at its current distance, but at much lower concentrations, and “it could never catch the more interesting particles”, said Mark McCaughrean, Scientific Advisor for the European Space Agency.
Scientists will also be able, thanks to pictures taken by Rosetta, to compare the appearance of the comet before and after perihelion. These images, the gas samples and other measurements made by the probe should provide new information on the composition of the comet and its cycle.
Philae has been stuck on the comet since its turbulent landing on November 12, 2014. After seven months of hibernation, it regained contact eight times with Rosetta. But since July 9, when it issued its last signal, it has remained silent.
“Philae may be active … but as we have no contact, we know nothing of its condition,” said the head of the Rosetta mission Patrick Martin.
When the comet moves away from the sun, and when the gas storms calm, scientists hope to send Rosetta closer to the comet to try and re-establish contact with the precious little robot.
More on the Rosetta mission