Category Astronomy/Space

Top: Gamma rays (magenta lines) coming from a bright source like NGC 1275 in the Perseus galaxy cluster should form a particular type of spectrum (right). Bottom: Gamma rays convert into hypothetical axion-like particles (green dashes) and back again when they encounter magnetic fields (gray curves). The resulting gamma-ray spectrum ((lower curve at right) would show unusual steps and gaps not seen in Fermi data, which means a range of these particles cannot make up a portion of dark matter. Credits: SLAC National Accelerator Laboratory/Chris Smith

Dark matter, the mysterious substance that constitutes most of the material universe, remains as elusive as ever...

This is an infographic explaining the fact that 10 trillionths of a suntan comes from beyond our galaxy. Credit: ICRAR/Dan Hutton

Lie on the beach this summer and your body will be bombarded by about sextillion photons of light per second.Most of these photons, originate from the Sun but a very small fraction have travelled across the Universe for billions of years before ending their existence when they collide with your skin. Astronomers have now accurately measured the light hitting Earth from outside our galaxy over a very broad wavelength range. The research looked at photons whose wavelengths vary from a fraction of a micron (damaging) to millimetres (harmless).

But radiation from outside the galaxy constitutes only ten trillionths of your suntan, so there is no immediate need for al...

NASA’s Hubble Space Telescope has captured the glow of new stars in these small, ancient galaxies, called Pisces A and Pisces B. The dwarf galaxies have lived in isolation for billions of years and are just now beginning to make stars. Credit: NASA, ESA, and E. Tollerud (STScI)

Hubble has uncovered 2 tiny dwarf galaxies that have wandered from a vast cosmic wilderness into a nearby “big city” packed with galaxies. After being quiescent for billions of years, they are ready to party by starting a firestorm of star birth. “These Hubble images may be snapshots of what present-day dwarf galaxies may have been like at earlier epochs,” said Erik Tollerud of the Space Telescope Science Institute in Baltimore, Maryland...

This simulation of the large-scale structure of the universe reveals the cosmic web of galaxies and the vast, empty regions known as voids. Credit: Image by Nico Hamaus, Universitäts-Sternwarte München, courtesy of The Ohio State University

A lot of information contained in cosmic voids, study suggests. An international team of astronomers reports that they were able to achieve 4X better precision in measurements of how the universe’s visible matter is clustered together by studying the empty spaces in between. Researchers looking for new ways to probe gravity and dark energy adopted a new strategy: looking at what’s not there.

Paul Sutter, Ohio State University, said that the new measurements can help bring astronomers closer to testing Einstein’s general theory of relativity, which des...