NASA's Mars InSight lander may have just measured and recorded for the first time an earthquake - well, in this case, a "Marsquake".  InSight made its landing in November of 2018 for the purpose of tracking any seismic waves rippling through its interior.  It is part of NASA's Discovery Program, managed by the agency's Marshall Space Flight Center in Huntsville, Alabama.

This was based on an audio recording (accompanied with a video interpretation) released by NASA last April 23 which lasted for about 40 seconds.  According to NASA, this is the first recorded trembling that appears to have come from inside the planet, as opposed to being caused by forces above the surface, such as wind.  The event happened on April 6.  The surface of Mars is extremely quiet, which allowed InSight to record the faint yet unmistakable rumble.  

"InSight's first readings carry on the science that began with NASA's Apollo missions," said InSight Principal Investigator Bruce Banerdt of NASA's Jet Propulsion Laboratory (JPL) - manages InSight for NASA's Science Mission Directorate in Pasadena, California. 

In its Apollo mission, NASA installed seismometers measuring thousands of quakes while operating on the Moon between 1969 and 1977, revealing seismic activity on the Moon. Different materials can change the speed of seismic waves or reflect them, allowing scientists to use these waves to learn about the interior of the Moon and model its formation.

"The Martian Sol 128 event is exciting because its size and longer duration fit the profile of moonquakes detected on the lunar surface during the Apollo missions," said Lori Glaze, Planetary Science Division director at NASA Headquarters.

There had been other events recorded, March 14, April 10 and April 11, but they were smaller in comparison to the April 6 event, and their origins more ambiguous but according to the team, they will continue to study all the data from these events to determine their cause.

According to Philippe Lognonné, SEIS team lead at the Institut de Physique du Globe de Paris (IPGP) in France, they have been waiting for an event such as this since although the recording isn't long enough to provide much information about the Martian interior, they finally have proof that shows that Mars is still seismically active - and kicks off a brand-new field of research: Martian seismology.

Scientists hope that InSight's data will ultimately reveal the planet's internal structure, including the size and density of its crust, mantle, and core, how heat flows through the planet, and even whether there might be water in the interior.