Astronomers have made the most precise test ever of general relativity outside the Milky Way.

A nearby galaxy acts as a strong gravitational lens, distorting light from a distant galaxy behind it to create an Einstein ring around its centre. By comparing the mass of the lensing galaxy with the curvature of space around it, the astronomers found that gravity on these astronomical length-scales behaves as predicted by general relativity.

The video is available in 4K UHD.

The ESOcast Light is a series of short videos bringing you the wonders of the Universe in bite-sized pieces. The ESOcast Light episodes will not be replacing the standard, longer ESOcasts, but complement them with current astronomy news and images in ESO press releases.

Directed by: Nico Bartmann.
Editing: Nico Bartmann.
Web and technical support: Mathias André and Raquel Yumi Shida.
Written by: Stephen Molyneux and Richard Hook.
Music: tonelabs (http://www.tonelabs.com).
Footage and photos: ESO, ESA, Hubble, M. Kornmesser, J. Colosimo, ALMA, NRAO, NAOJ, L. Calçada and the Hubble Heiratage Team (STScl/AURA).
Executive producer: Lars Lindberg Christensen.

Introduction to ecosystems and biomes. Watch the next lesson: https://www.khanacademy.org/science/biology/ecology/intro-to-ecosystems/v/flow-of-energy-and-matter-through-ecosystems Missed the previous lesson? Watch here: https://www.khanacademy.org/science/biology/ecology/community-structure-and-diversity/v/ecological-succession Ecology on Khan Academy: Why are polar bears found only in the Arctic? Why does mildew grow in your shower and not (hopefully) in your sock drawer? Learn how ecologists study the interactions between organisms and their environment,…

Practice this lesson yourself on KhanAcademy.org right now: https://www.khanacademy.org/math/trigonometry/basic-trigonometry/cc-trig-ratios-similarity/e/trigonometric-functions-and-side-ratios-in-right-triangles?utm_source=YT&utm_medium=Desc&utm_campaign=Trigonometry Watch the next lesson: https://www.khanacademy.org/math/trigonometry/basic-trigonometry/trig-application-problems/v/how-much-of-a-pyramid-is-submerged?utm_source=YT&utm_medium=Desc&utm_campaign=Trigonometry Missed the previous lesson? https://www.khanacademy.org/math/trigonometry/basic-trigonometry/cc-trig-ratios-similarity/v/example-with-trig-functions-and-ratios?utm_source=YT&utm_medium=Desc&utm_campaign=Trigonometry Trigonometry on Khan Academy: Big, fancy word, right? Don’t be fooled. Looking at the prefix, tri-, you could probably assume that trigonometry (“trig” as it’s sometimes called) has something to do with triangles. You would be…

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