An article published in “The Astronomical Journal” reports a description of the characteristics of comet P/2019 LD2. A team of researchers used observations conducted with various space and ground-based telescopes to examine P/2019 LD2 while it’s passing near the planet Jupiter in a trajectory that brought it close to the Trojan asteroids to the point that it was initially mistaken for one of them.
An article published in the journal “Nature” reports a reconstruction of the trajectory of ESA’s Rosetta mission’s Philae lander in its touchdown on the surface of comet 67P/Churyumov-Gerasimenko. A team of researchers examined data collected by the Rosetta space probe and the Philae lander to find out where the latter made its second touchdown on the comet, which was followed by further bounces before finally landing. The study also showed that the affected materials contained an abundant amount of ice as soft as freshly laid snow, to the point of being described as softer than cappuccino froth.
An article published in the journal “Monthly Notices of the Royal Astronomical Society” reports a study indicating that the interior of the nucleus of comet 67P/Churyumov-Gerasimenko is porous and less dense than its surface. A team of researchers reviewed data collected by ESA’s Rosetta space probe and its Philae lander’s CONSERT instrument. The signals exchanged between them through the cometary nucleus propagated at different speeds, indicating a varying density of its interior. This suggests that solar radiation changed the surface, making it less porous.
The Hubble Space Telescope was used to observe comet NEOWISE, formally C/2020 F3, which notably shows the coma surrounding its nucleus. The images released were captured on August 8, and are the first photos taken by Hubble of such a bright comet at such a high resolution after it passed close to the Sun. On July 3, NEOWISE passed approximately 43 million kilometers from the Sun, the most critical moment because sometimes comets are torn to pieces. The new images show that this time the comet survived in its entirety and will return to the inner solar system only in 7,000 years.
An article published in the journal “Nature Astronomy” reports a study on the interstellar comet 2I/Borisov focused in particular on its chemical composition which highlights the abundance of carbon monoxide and hydrogen cyanide. A team of researchers led by Martin Cordiner and Stefanie Milam of NASA’s Goddard Space Flight Center used the ALMA radio telescope to examine the comet’s emissions detecting that carbon monoxide is present in its coma in an amount that is between 9 and 26 times that estimated for the solar system’s comets. This suggests that it formed in a very cold area of its origin system.
