A galaxy cluster 4.6 billion light-years away bends the light of galaxies behind it into arcs

the gist

Gravitational lensing happens when a massive object, here a galaxy cluster, bends the path of light from objects behind it. Because mass curves space, light from distant galaxies follows a curved route around the cluster and is magnified and stretched into arcs. The cluster SPT-CL J0019-2026 in Cetus lies about 4.6 billion light-years away, and the arcs around it are galaxies far beyond it. Lensing works like a natural telescope, letting astronomers see objects too faint and distant to observe directly. This image came from a project using Hubble's spare observing time to explore the most massive distant clusters, hoping to find promising targets for future study with Hubble and the James Webb Space Telescope.

how it works

Einstein's general relativity says mass curves spacetime, so light passing a massive object follows a bent path. A strong lens can produce multiple images and stretched arcs of a background galaxy. The magnification helps astronomers study galaxies that would otherwise be too dim to detect.

so what

Lensing is a key tool for mapping how mass is distributed, including dark matter, which emits no light but still bends it. It also lets astronomers observe very early galaxies that would otherwise be out of reach.

fun fact

The bending of starlight by the Sun was first measured during a 1919 solar eclipse, a key test of Einstein's general relativity.

ESA/Hubble · CC BY 4.0

Image: ESA/Hubble & NASA, H. Ebeling

source: ESA/Hubble ↗

historyWikipediaclassic1336–1565 · Karnataka, India

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 ↗