Astronomy Archives

January 3, 2024January 3, 2024 by Scott Alan Johnston

Iron Snow Could Explain the Magnetic Fields at Worlds Like Ganymede

Iron snow in the core of Ganymede. Credits: Image by Ludovic Huguet and map texture from NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Jupiter’s largest moon, Ganymede, features a surprisingly strong magnetic field for its size. Tidal effects from Jupiter continually stretch and squeeze the moon, keeping its core warm and driving the magnetic field. But the exact geological processes occurring within the core are not fully understood. Now, a new experimental study has put one of the leading models of core dynamics to the test: the formation of crystalized ‘iron snow’.

January 3, 2024January 3, 2024 by Evan Gough

The Oldest Known Spiral Galaxy Has Ripples Like the Surface of a Pond

This simulation illustrates a galaxy disk being disturbed, leading to the propagation of a seismic ripple throughout the disk. (Credit: Bland-Hawthorn and Tepper-Garcia, University of Sydney).

Astronomers have detected pond-like ripples across the gaseous disk of an ancient galaxy. What caused the ripples, and what do they tell us about the distant galaxy’s formation and evolution? And whatever happened, how has it affected the galaxy and its main job: forming stars?

January 2, 2024January 3, 2024 by Matt Williams

After all of This Time Searching for Aliens, is it The Zoo Hypothesis or Nothing?

The Karl Jansky Very Large Array at night, with the Milky Way visible in the sky. Credit: NRAO/AUI/NSF; J. Hellerman

In 1950, during a lunchtime conversation with colleagues at the Los Alamos National Laboratory, famed physicist Enrico Fermi asked the question that launched a hundred (or more) proposed resolutions. “Where is Everybody?” In short, given the age of the Universe (13.8 billion years), the fact that the Solar System has only existed for the past 4.5 billion years, and the fact that the ingredients for life are everywhere in abundance, why haven’t we found evidence of extraterrestrial intelligence by now? This came to be the basis of Fermi’s Paradox, which remains unresolved to this day.

Interest in Fermi’s question has been piqued in recent years thanks to the sheer number of “potentially habitable” exoplanets discovered in distant star systems. Despite that, all attempts to find signs of technological activity (“technosignatures”) have come up empty. In a recent study, a team of astrobiologists considered the possible resolutions and concluded that only two possibilities exist. Either extraterrestrial civilizations (ETCs) are incredibly rare (or non-existent), or they are deliberately avoiding contact with us (aka. the “Zoo Hypothesis“).

January 2, 2024January 2, 2024 by Evan Gough

You’ll Need all the Internet to Download the Full Resolution of this New Running Chicken Nebula Image

The Running Chicken Nebula comprises several clouds, all of which we can see in this vast image from the VLT Survey Telescope (VST), hosted at ESO’s Paranal site. This 1.5-billion pixel image spans an area in the sky of about 25 full Moons. Image Credit: ESO/VST

Over 6,000 light-years from Earth, an open star cluster and its nebula cover a swathe of sky over 270 light-years across. It’s called the Running Chicken Nebula, and it’s more than just one object. The Running Chicken Nebula, also called IC 2944, also contains IC 2948, the brightest part of the Chicken, as well as several Bok Globules and smaller nebulae. The bright star Lambda Centauri is near the visual center of the Chicken but is actually much closer to Earth.

January 1, 2024January 1, 2024 by Mark Thompson

ESA’s Tiny Pinhole Thruster is Ready for Production.

ATHENA - Adaptable, THurster based on Electrospray powered NAnotechnology

Rocket propulsion technology has progressed leaps and bounds since the first weaponised rockets of the Chinese and Mongolian empires. They were nothing more than rocket powered arrows and spears but they set the foundations for our exploration of space. Liquid propellant, ion engines and solar sails have all hit the headlines as we strive for more efficient methods of travel but a team has taken the next leap with a palm sized thruster system that could boost future tiny space craft across the gulf of space.

December 31, 2023December 31, 2023 by Carolyn Collins Petersen

How a Small Town in Japan Fiercely Defends its Dark Skies

The arch of the Milky Way seen over Bisei Town in Japan. It prides itself on its dark skies, but faces scattered light pollution from other nearby municipalities. Courtesy DarkSky.Org.

Light pollution ruins dark skies. It’s a scourge that ground-based observatories have to deal with in one form or another. Scientists used a small observatory in Japan to measure what changed when a nearby town improved its lighting practices. They also noted the challenges it still faces.

December 27, 2023December 18, 2023 by Paul M. Sutter

Why Quantum Mechanics Defies Physics

The full, weird story of the quantum world is much too large for a single article, but the period from 1905, when Einstein first published his solution to the photoelectric puzzle, to the 1960’s, when a complete, well-tested, rigorous, and insanely complicated quantum theory of the subatomic world finally emerged, is quite the story.

December 26, 2023December 18, 2023 by Paul M. Sutter

We Owe Our Lives to the Moon

Occultation — The occultation of Aldebaran by the Moon in 2016. Credit: Andrew Symes.

Life appeared on Earth through a series of lucky coincidences, and that luck started with our Moon. None of the other planets of the inner solar system have significant moons. Space is lonely around Mercury and Venus. Mars does have two small moons, Phobos and Deimos (Fear and Despair, befitting companions for the God of War), but those are simply captured asteroids, lassoed in the not-too-distant past and doomed to eventually come close enough to their unloving parent to be torn to shreds by gravitational forces.

December 26, 2023February 26, 2024 by David Dickinson

Top Astronomy Events for 2024

Astronomy 2024 features the final total solar eclipse for the CONUS until 2044, and much more.

It’s finally time. On April 8^th, 2024, the umbral shadow of the Moon crosses the United States for the second time in less than seven years. It’s a big deal, for sure. But there’s lots more in store for astronomy 2024. Here’s our annual Universe Today rundown for top skywatching events to watch for in astronomy 2024, coming to a sky near you.

December 23, 2023December 18, 2023 by Paul M. Sutter

How Supersymmetry Saved String Theory

According to supersymmetry, dark-matter particles known as neutralinos (which are often called WIMPs) annihilate each other, creating a cascade of particles and radiation that includes medium-energy gamma rays. If neutralinos exist, the LAT might see the gamma rays associated with their demise. Credit: Sky & Telescope / Gregg Dinderman.

String theory, like most revolutions, had humble origins. It started all the way back in the 1960’s as an attempt to understand the workings of the strong nuclear force, which had only recently been discovered. Quantum field theory, which had been used successfully to explain electromagnetism and the weak nuclear force, wasn’t seeming to cut it, and so physicists were eager for something new.