The European Space Agency’s (ESA) ‘Solar Orbiter’ probe had a chance encounter with the exploded comet ATLAS, which flew through its dusty tail.
This gave astronomers a unique opportunity to study the remains of a frozen object formed in the most remote regions of the solar system.
ATLAS was discovered in December 2019 and initially suggested it would become one of the brightest comets visible to the naked eye, but it began to disintegrate in March 2020 when it got closest to the sun.
It left its tail as it disintegrated, and in June 2020, the ESA Solar Orbiter passed through the comet’s tail as it traveled toward the sun to begin its mission.
Studying data from the probe’s instruments, experts at Imperial College London found that the sun’s background magnetic field “falls” over the comet, carried by solar winds.
They hope that if the probe, and the NASA Parker Solar Probe that also studies the sun, the remains of the comet can be examined in more detail in the coming years.
April 2020 Hubble Space Telescope observations recorded the ATLAS comet breaking apart as it got closer to the sun
The meeting with ATLAS, pictured, was not planned – the Solar Orbiter probe was launched in February to study the sun up close, with a focus on the star’s polar regions
ESA’s Solar Orbiter ‘accidentally’ passes through the tails of comet ATLAS
ESA’s Solar Orbiter probe will ‘accidentally’ pass through the tails of Comet ATLAS at the end of May.
Scientists enlisted four of the spacecraft’s instruments specifically to take advantage of this rare opportunity to conduct “bonus science.”
The meeting with ATLAS was not planned – the Solar Orbiter probe was launched in February to study the sun up close, focusing on the star’s polar regions.
Planetary scientist Geraint Jones of Britain’s Mullard Space Science Laboratory has brought the Solar Orbiter mission to the window for data collection.
The probe collected data on the individual trails of dust and charged particles released by the comet, which was slowly vaporized by the sun’s solar radiation.
The craft passed within 27.3 million miles (44 million km) of the comet’s nucleus, or “nucleus,” through the ion tail on May 31-June 1, and the dust tail on June 6.
Comet tails are made up of dust and charged particles that interact with the solar winds as they enter the inner solar system and feel the influence of the sun.
Sometimes, as was the case with ATLAS, the solar radiation breaks them apart, and the Hubble Space Telescope observed this moment of destruction in April 2020.
Shortly after launch, the Solar Probe team realized its path would go through the comet’s tail, something it was not designed for.
In fact, the onboard instruments wouldn’t be turned on until much later in the mission, but they decided to see if they could “make it work.”
After the comet broke up, the team wasn’t sure if there was anything to discover, but they continued plans to switch on the instruments early and meet the comet’s tail.
As it passed through the remains of the tail, astronomers turned on all of the in-situ instruments on the Solar Probe to get the widest possible view.
They found that the “environmental interplanetary magnetic field,” a field of particles carried by solar winds, “curtains” around the comet.
It then surrounds a central tail region with a weaker magnetic field, they found.
Comets are usually characterized by two separate tails; one is the familiar bright and curved dust tail, the other – usually fainter – is the ion tail.
The ion tail is created by the interaction between the comet gas and the surrounding solar wind, the hot gas of charged particles that constantly blows off the sun and permeates the entire solar system.
When the solar wind interacts with a solid obstacle, such as a comet, its magnetic field is thought to bend and “drape” around it.
Researchers ‘recreated’ the encounter with the comet, and in this diagram, lines identify interplanetary magnetic field lines in the solar wind that are draped around the comet
The Hubble Space Telescope captured the breakup of comet C/2019 Y4 (ATLAS). On the left an image from April 20 with 30 fragments and on the right an image from April 23 with another 25 pieces
The simultaneous presence of magnetic field cover and comet ions released by the melting of the icy nucleus then produces the characteristic second ion tail, which can extend great distances downstream from the comet’s nucleus.
Lorenzo Matteini, a solar physicist at Imperial College London and leader of the work, described it as a “unique event.”
Adding it is also an “exciting opportunity for us to study the composition and structure of comet tails in unprecedented detail.”
“Hopefully, with the Parker Solar Probe and Solar Orbiter now orbiting closer to the sun than ever before, these events can become much more common in the future!”
ATLAS was discovered in December 2019 and it was initially suggested that it would become one of the brightest comets visible to the naked eye, but it began to disintegrate in March 2020. The Solar Orbiter (artist impression pictured) went through the tail in June 2020.
ESA says the instruments on the spacecraft ‘work beautifully’, providing a holistic view of the sun and solar wind in a way never seen before
It was one of the few cases where scientists have been able to make direct measurements from a fragmented comet.
The data from this encounter is expected to greatly contribute to scientists’ understanding of the interaction of comets with the solar wind and the structure and formation of their ion tails.
This, in turn, could help figure out why they break up as they get closer to the inner solar system.
The findings were presented at the Royal Astronomical Society National Astronomy Meeting.
Explained: the difference between an asteroid, meteorite and other space rocks
A asteroid is a large piece of rock left over from collisions or the early solar system. Most are located between Mars and Jupiter in the Main Belt.
A comet is a rock covered with ice, methane and other compounds. Their orbits take them much further out of the solar system.
A meteor is what astronomers call a flash of light in the atmosphere when debris burns up.
This debris itself is known as a meteoroid. Most are so small that they evaporate into the atmosphere.
When one of these meteoroids reaches Earth, it becomes a . mentioned meteorite.
Meteors, meteoroids and meteorites normally originate from asteroids and comets.
For example, if Earth passes through the tail of a comet, much of the debris in the atmosphere burns up, forming a meteor shower.