Rendezvous with a comet’s tail

Lorenzo Matteini, Imperial College London, UK, led another painstaking investigation to determine whether Solar Orbiter has crossed the tail of Comet ATLAS during June 2020.

The possible crossing was predicted shortly after Solar Orbiter’s launch and so the team scrambled to make sure at least some instruments were ready in time to acquire data. By a rather cruel twist of fate, however, just ten days before the crossing, the comet disintegrated under the heat of the Sun and the beautiful tail faded.

Nevertheless, Lorenzo and his colleagues found evidence consistent with a crossing of the comet’s tail remnant in data taken on 4 June. Specifically, they saw the magnetic field around Solar Orbiter suddenly change its polarity, which would be expected if the Sun’s magnetic field were draped around a piece of the broken comet’s nucleus.

“This is the first time that we have encountered a comet tail inside Earth’s orbit,” says Lorenzo.

And it may not be the last. Comets are falling in towards the Sun all the time. The way they interact with the Sun’s magnetic field provides yet another way for Solar Orbiter to investigate this fascinating region of the solar system.

Following its November 2021 flyby of Earth, Solar Orbiter is now in its main science phase. All involved are preparing for its close pass of the Sun in March 2022.

“I couldn’t be more pleased with the mission. These results show both how much great science has already been done, and how much there is still to come,” says Daniel Müller, ESA Project Scientist for Solar Orbiter.

Notes for editors

Solar Orbiter’s cruise phase results are published in the December 14 special edition of Astronomy and Astrophysics.

The papers highlighted in this news story, published alongside 52 other Solar Orbiter papers are:

Capturing transient plasma flows and jets in the solar corona by L. P. Chitta et al.

The first widespread solar energetic particle event observed by Solar Orbiter on 2020 November 29 by A. Kollhoff et al.

Solar origins of a strong stealth CME detected by Solar Orbiter by Jennifer O’Kane et al.

Solar Orbiter’s encounter with the tail of comet C/2019 Y4 (ATLAS): magnetic field draping and cometary pick-up ion waves by L. Matteini et al.

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