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What is time? An astronomer explains
Quantum entanglement — when the states of two particle are intertwined by the laws of quantum mechanics — has long vexed physicists. But the phenomenon may also hold the key to understanding how time emerged. Credit: J Jurik Peter/Shutterstock (This article was originally published in the May 2022 issue of Astronomy). St. Augustine said of…
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Retrograde motion explained: what is retrograde motion in astronomy
Why do planets sometimes seem to move “backward”? Is such a motion even real? Should you fear Mercury retrograde? You’ll find answers to these questions in our article. Contents You can also check out our infographic, where we explain how retrograde motion works. Want to know what causes the apparent retrograde motion of the planets?…
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Royal Observatory
Greenwich Outrage 130th anniversary event Join us for a panel discussion with academics, writers and broadcasters about the Greenwich Outrage, followed by a screening of Alfred Hitchcock’s Sabotage, which was loosely inspired by the incident
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JWST catches galactic ‘cat’s tail’ in Beta Pictoris system
An image of the cat’s tail found in the Beta Pictoris system. The black shadow seen in the middle of the image is a coronagraph and was used to block out the central star’s brightness. Credit: NASA, ESA, CSA, STScI, Christopher Stark (NASA-GSFC), Kellen Lawson (NASA-GSFC), Jens Kammerer (ESO), Marshall Perrin (STScI) Beta Pictoris, a…
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The Magellanic Clouds: astronomers make the case for a name change
The Magellanic Clouds are prominent features of the southern sky that are named after the Portuguese explorer Ferdinand Magellan. He sailed west from Europe to the Philippines in the early 16th century and the clouds were described by a returning crew member. Voyages such as Magellan’s set into motion the European colonization of much of…
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Astronomers spotted something perplexing near the beginning of time
Not long after the James Webb Space Telescope came online in 2022, astronomers’ jaws hit the floor. “I remember thinking, This just can’t be right!” says Mike Boylan-Kolchin, a University of Texas Austin astronomer. The observations he’s referring to would, to you and me, seem like little smudgy red blobs among a field of other…
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James Webb telescope discovers the oldest, most distant black hole in the universe
Editor’s note: An earlier version of this article was published on Dec. 17, 2023. The article was updated to reflect that the study has been published in the peer-reviewed journal Nature. The James Webb Space Telescope (JWST) has spotted the oldest black hole ever seen, an ancient monster with the mass of 1.6 million suns…
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Is there any sound in space? An astronomer explains
Matter in deep space is spread out, which makes it impossible for any sound waves to travel. Credit: NASA How far can sound travel through space, since it’s so empty? Is there an echo in space? – Jasmine, age 14, Everson, Washington In space, no one can hear you scream. You may have heard this…
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Astronomers detect oldest black hole ever observed
The international team, led by the University of Cambridge, used the NASA/ESA/CSA James Webb Space Telescope (JWST) to detect the black hole, which dates from 400 million years after the big bang, more than 13 billion years ago. The results, which lead author Professor Roberto Maiolino says are “a giant leap forward”, are reported in…
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Will we ever figure out how to defy gravity?
The gravitational force is by far the weakest of the four forces of nature. It’s simple to defy gravity: just lift something in the air. But the annoying thing about gravity is that it’s both persistent and has an infinite range, which takes a surprising amount of work to overcome. Gravity is so weak that…