Earth's gravity may have kept the early moon's volcanic heart beating

science & techPhys.orgc. 4.5 billion years ago

Earth's gravity may have kept the early moon's volcanic heart beating

from Phys.org

We typically think of the moon as a static, floating object that has remained the same for basically its entire lifetime, with an occasional asteroid impact serving as an exception. That understanding is grounded in physics—the moon should have cooled rapidly after forming when a huge protoplanet hit the early Earth around 4.5 billion years ago. But some lunar material returned from the Chang'e-5 mission was notably formed only around 2 billion years ago, yet appeared to be volcanic in origin.

explained

The Moon is the only natural satellite of Earth. It orbits Earth in an elliptical path, at a distance that varies over the year, averaging around 378,000 kilometers (235,000 mi). It completes an orbit (lunar month) in relation to Earth and the Sun (synodically) every 29.5 days. The Moon and Earth are bound by gravitational attraction, which is stronger on the sides facing each other. The resulting tidal forces are the main driver of Earth's tides, and have pulled the Moon to always face Earth with the same near side. This tidal locking effectively synchronizes the Moon's rotation period (lunar day) to its orbital period (lunar month).

From Wikipedia: Moon (CC BY-SA 4.0) ↗

so what

It challenges the idea that the Moon is a dead, unchanging rock and shows that Earth's gravity could drive internal activity in a neighbouring world. Understanding this helps geologists reconstruct how the Earth-Moon system evolved together.

fun fact

The Moon is slowly drifting away from Earth, about 3.8 centimetres per year.

Hampi was once one of the world's largest cities, until its Vijayanagara capital was destroyed in 1565

the gist

Hampi is a UNESCO World Heritage Site in Karnataka, India, with more than 1,600 surviving remains spread over 4,100 hectares. It was the capital of the Vijayanagara Empire from 1336 to 1565. Travellers from Persia and Portugal described it as a prosperous, wealthy and grand city with temples, markets and farms along the Tungabhadra River. By 1500 it was estimated to be the world's second-largest city after Beijing, and probably India's richest at the time. In 1565 a coalition of Muslim sultanates defeated the Vijayanagara Empire, its capital was conquered and destroyed, and the city was left in ruins. Hampi remains a religious centre, with the active Virupaksha Temple at its heart.

how it works

The city was built around a fortified core with temples, markets and water structures along the river, supplied by an extensive network of roads and waterworks. When the empire fell, the city was not rebuilt, so its stone monuments were left standing.

so what

Hampi shows how quickly a great city can vanish after a military defeat, and how a ruined capital can remain sacred. Its ruins give historians a view of medieval South Asia that few other sites can match.

fun fact

The name Hampi comes from Pampa, an old name for the Tungabhadra River.

From Wikipedia, the free encyclopedia · text CC BY-SA 4.0

Image: Wikimedia Commons

source: Wikipedia ↗

2 min

politicsshortCNA2:01

False allegations about Singapore’s hand in Indonesia’s markets and a made-up meeting

from CNA

CNA Verify has found close to 400 posts pushing falsehoods tying Singapore to Indonesia’s stock market rout and to a secret meeting that never took place. Together, they drew nearly 12 million views, and some were circulated by accounts that appeared to be working in concert, across multiple social media platforms.

Here’s how the disinformation campaign targeting Singapore was uncovered.

on YouTube: CNA ↗