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Space

What is a galaxy? That's a surprisingly difficult question to answer

Figuring out what really counts as a galaxy could give us insights into dark matter and potentially shake up astrophysics, cosmology and particle physics, says columnist Chanda Prescod-Weinstein

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A huge cloud of dark matter may be lurking near our solar system

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Dark Matter distribution

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The best map of dark matter has revealed never-before-seen structures

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little red dots

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Distant 'little red dot' galaxies may contain baby black holes

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This new NASA/ESA/CSA James Webb Space Telescope Picture of the Month features a rare cosmic phenomenon called an Einstein ring. What at first appears to be a single, strangely shaped galaxy is actually two galaxies that are separated by a large distance. The closer foreground galaxy sits at the center of the image, while the more distant background galaxy appears to be wrapped around the closer galaxy, forming a ring.?? Einstein rings occur when light from a very distant object is bent (or ???lensed???) about a massive intermediate (or ???lensing???) object. This is possible because spacetime, the fabric of the Universe itself, is bent by mass, and therefore light travelling through space and time is bent as well. This effect is much too subtle to be observed on a local level, but it sometimes becomes clearly observable when dealing with curvatures of light on enormous, astronomical scales, such as when the light from one galaxy is bent around another galaxy or galaxy cluster. When the lensed object and the lensing object line up just so, the result is the distinctive Einstein ring shape, which appears as a full circle (as seen here) or a partial circle of light around the lensing object, depending on the precision of the alignment. Objects like these are the ideal laboratory in which to research galaxies too faint and distant to otherwise see. The lensing galaxy at the center of this Einstein ring is an elliptical galaxy, as can be seen from the galaxy???s bright core and smooth, featureless body. This galaxy belongs to a galaxy cluster named SMACSJ0028.2-7537. The lensed galaxy wrapped around the elliptical galaxy is a spiral galaxy. Even though its image has been warped as its light travelled around the galaxy in its path, individual star clusters and gas structures are clearly visible. The Webb data used in this image were taken as part of the Strong Lensing and Cluster Evolution (SLICE) survey (programme 5594), which is led by Guillaume Mahler at University of

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I'm calling it – 2026 is going to be the year of the galaxy

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Weird clump in the early universe is piping hot and we don’t know why

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The supernova remnant Cassiopeia A

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Odd elements in supernova blast might have implications for alien life

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Supermassive dark matter stars may be lurking in the early universe

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Astronomers may have glimpsed evidence of the biggest stars ever seen

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Mystery deepens as isolated galaxy forms stars with no obvious fuel

A galaxy in a practically empty area of the universe seems to be impossibly forming stars, and new observations have only deepened the puzzle

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A distant galaxy is being strangled by the cosmic web

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Brightest black hole flare ever caused by huge star being ripped apart

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We may have found a surprisingly nearby cluster of primordial stars

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A tiny nearby galaxy is home to a shockingly enormous black hole

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