Seismic waves generated by a meteorite impact on the other side of Mars from where NASA’s InSight lander sits have provided new clues about the Red Planet’s deep interior, prompting scientists to reappraise the anatomy of Earth’s planetary neighbour.

The new seismic data indicates the presence of a hitherto unknown layer of molten rock surrounding a liquid metallic core – the planet’s innermost component – that is smaller and denser than previously estimated, researchers said on Wednesday.

Waves generated by quakes – including those caused by meteorite impacts – vary in speed and shape when journeying through different materials inside a planet. Data from InSight’s seismometer instrument has enabled the planet’s internal structure to come into focus.

The meteorite impact that occurred in a Martian highland region called Tempe Terra on Sept. 18, 2021, triggered a magnitude 4.2 quake and left a crater about 425 feet (130 meters) wide. It occurred on the opposite side of Mars from InSight’s location in a plains region called Elysium Planitia.

“The importance of the far side impact was to produce seismic waves that traversed the deep interior of the planet, including the core. Previously, we had not observed any seismic waves that had transited the core. We had only seen reflections from the top of the core,” said planetary scientist Amir Khan of ETH Zurich in Switzerland, lead author of one of two scientific papers on the new findings published in the journal Nature.

The behaviour of the waves indicated that previous assessments of the Martian interior were missing something – the presence of a molten silicate layer about 90 miles (150 km) thick surrounding the core. This molten region sits at the bottom of the interior portion of the planet called the mantle.

The researchers also recalculated the size of the core, finding that it has a diameter of about 2,080 miles (3,350 km), with a volume about 30% smaller than previously thought.

The researchers said the mantle – a rocky layer sandwiched between the planet’s outermost crust and core – extends about 1,055 miles (1,700 km) below the surface. Unlike Mars, Earth has no molten layer around its core. One of the two studies published on Wednesday indicates this layer is fully molten, with the other indicating that most of it is fully molten, with the top portion partially molten.

“The molten and partially molten layer is essentially composed of silicates (rock-forming minerals) that are enriched in iron and in radioactive heat-producing elements compared to the overlying solid mantle,” said Henri Samuel, a planetary scientist with the French National Research Organization CNRS working at Institut de Physique du Globe de Paris and lead author of the second study.

The Martian core is made up mostly of iron and nickel but also has some lighter elements such as sulfur, oxygen, carbon and hydrogen. The researchers concluded that these lighter elements make up about 9-15% of the core’s composition by weight, lower than previously estimated.

“This amount of light elements is not unlike that of the Earth’s core, which is estimated to be around 10%,” Khan said.

Mars, the fourth planet from the sun, has a diameter of about 4,220 miles (6,791 km), compared to Earth’s diameter of about 7,926 miles (12,755 km). Earth is almost seven times larger in total volume.

NASA retired InSight in 2022 after four years of operations.

“We have learned a lot about Mars by studying the unique seismic record provided by the InSight mission,” Samuel said. “Planets are rich and complex systems because they are a place where many different types of processes coexist and act on various spatial and temporal scales, and Mars is no exception.”

An earthquake of magnitude 4.5 on the Richter Scale jolted China’s Xinjiang region on Wednesday, the National Centre for Seismology (NCS) reported.

The depth of the quake that occurred at 21:22:18 IST today was found to be 10 km.

“Earthquake of Magnitude:4.5, Occurred on 25-10-2023, 21:22:18 IST, Lat: 36.55 & Long: 84.29, Depth: 10 Km, Region: Xinjiang,” the NCS posted on X.

No casualties are reported.

Further details are awaited.

A female unit within the Israel Defense Forces eliminated nearly 100 Hamas operatives during an attack on October 7, the Jerusalem Post reported. Israeli commander Caracal commander Lt.-Col. Or Ben-Yehuda told the media outlet that the women “emerged as heroes” for their actions near the Gaza Strip. 

Commander Ben-Yehuda told the media outlet on the morning of October 7 when Hamas invaded Israel, she received a message reporting an infiltration of heavily armed militants near the kibbutzim of Sufa and Nirim.

She told her soldier, “Stay alert. We might cross paths. We are a strong squad.”

Upon her arrival at the Sufa kibbutz, Ben-Yehuda reported that she observed the substantial scale of the Hamas infiltration.

She revealed that the combat between the female battalion and the Hamas operatives lasted nearly 4 hours and included large firefights. It took about 14 hours for the IDF to secure the base. 

She shared that the female soldiers under her command have made significant contributions to the war effort.

“There are no more doubts about female combat soldiers, who have triumphed in every encounter with terrorists,” Ben-Yehuda said.

“At present, we are responsible for 11 towns and are preparing for any potential ground manoeuvres to ensure the safety of the southern Gaza border area and the Egyptian border.”

Ben-Yehuda shares that members of the female troop have saved countless lives through medical care or by bravely landing helicopters while under fire, too. 

The commander also expressed her appreciation for the tank soldiers she led, highlighting their crucial role in safeguarding communities, including Holit, a kibbutz adjacent to the Gaza Strip. Tragically, during this period, at least 11 kibbutz members and two migrant workers lost their lives.

Hamas stormed into Israel from the Gaza Strip on October 7 and killed at least 1,400 people, mostly civilians who were shot or burnt to death on the first day of the raid, according to Israeli officials.

Hamas also took 222 people hostage, among them elderly people and young children, according to the Israeli authorities’ latest count. The hostages include dozens of dual nationals and foreigners.

More than 5,000 Palestinians, mainly civilians, have been killed across the Gaza Strip in retaliatory Israeli bombardments, according to the latest number of dead from the Hamas health ministry in Gaza.