How big is the universe? What shape is it? How fast is it expanding? And when will it end? We answer these questions and more in our essential guide to the current state of cosmological knowledge
Category: space
Salt may have pushed us further into Snowball Earth 700 million years ago
Our planet plunged into one of the most dramatic climate states in its long history, approximately 720–635 million years ago. During a period geologists call Snowball Earth, ice sheets crept from the poles all the way to the tropics, covering the oceans and continents in a nearly global freeze.
Evidence for this extreme climate comes from rock formations around the world that bear the signatures of ancient glaciers at low latitudes—signs that Earth’s surface was encased in ice far beyond what we see in today’s polar regions.
Scientists have long studied how a feedback process known as ice-albedo helped lock in and amplify this deep chill. Albedo is a measure of how much sunlight a surface reflects; snow and ice are bright and reflect most of the sun’s energy back into space, cooling the planet further as more of it spreads across the surface.
New LVK catalog adds 128 gravitational-wave candidates, more than doubling detections
When the densest objects in the universe collide and merge, the violence sets off ripples, in the form of gravitational waves, that reverberate across space and time, over hundreds of millions and even billions of years. By the time they pass through Earth, such cosmic ripples are barely discernible.
And yet, scientists are able to detect them, thanks to a global network of gravitational-wave observatories: the U.S.-based National Science Foundation Laser Interferometer Gravitational-Wave Observatory (NSF LIGO), the Virgo interferometer in Italy, and the Kamioka Gravitational Wave Detector (KAGRA) in Japan. Together, the observatories “listen” for faint wobbles in the gravitational field that could have come from far-off astrophysical smash-ups.
Now the LIGO-Virgo-KAGRA (LVK) Collaboration is publishing its latest compilation of gravitational-wave detections, presented in a forthcoming special issue of Astrophysical Journal Letters. From the findings, it appears that the universe is echoing all over with a kaleidoscope of cosmic collisions.
What’s Really Happening on Venus? Scientists Reveal Surprising Patterns
Venus’ surface has long been hidden beneath thick clouds and sparse data, but new research is beginning to illuminate what conditions may actually be like on the ground.
What Geminga’s 100 TeV cutoff may mean for cosmic-ray acceleration in the Milky Way
For the first time, the Tibet ASγ Experiment has successfully measured magnetohydrodynamic (MHD) turbulence on scales below one parsec (approximately 3.3 light-years) within the gamma-ray halo surrounding the Geminga pulsar wind nebula (PWN). This observation extends to the highest energies, above 100 tera-electron volts (TeV), providing new insights into the behavior of cosmic rays and magnetic fields within the Milky Way.
The findings are published in Science Advances. The study was conducted by the Tibet ASγ Experiment, including the Institute of High Energy Physics (IHEP) of the Chinese Academy of Sciences (CAS) and the National Astronomical Observatories of CAS.
