There are a number of comets whizzing around the solar system, but in 2014 scientists got an unprecedented look at what happens when one comes within close range of a planet. According to a report from Discovery News, Comet C/2013 A1, otherwise known as Siding Spring, veered past Mars and caused chaos in the red planet’s magnetic fields.

The multiple rovers and probes on Mars caught a view of the comet as it flew by, but scientists were stunned when they checked the magnetometer orbiting 100 miles above the surface of the planet.

According to Jared Espley, a researcher with NASA’s Mars Atmosphere and Volatile Evolution spacecraft team, “Comet Siding Spring plunged the magnetic field around Mars into chaos. We think the encounter blew away part of Mars’ upper atmosphere, much like a strong solar storm would.”

The massive change caused by the comet may have something to do with the fact that Mars’ magnetic field is much weaker than the one here on Earth. While the center of the comet is only a third of a mile wide, the cloud of gas and ice surrounding it extends as much as 600,000 miles.

The cloud surrounding the comet is known as the coma, and it is formed when radiation from the sun causes ice to sublimate into space. Comets generate their own massive magnetic fields that extend throughout the coma. When Siding Spring flew within 87,000 miles of Mars, its magnetic field was sent into turmoil.

Mars provides a unique opportunity for researchers interested in studying how a comet can affect a planet’s atmosphere and magnetism. Because of its weak magnetic field and disappearing atmosphere, the effects of the interactions are especially pronounced.

“With MAVEN, we’re trying to understand how the sun and solar wind interact with Mars,” said MAVEN principal investigator Bruce Jakosky. “By looking at how the magnetospheres of the comet and of Mars interact with each other, we’re getting a better understanding of the detailed processes that control each one.”

A press release from the NASA/Goddard Space Flight Center describing the details of the study can be found here.