One Universe at a Time
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The goal of One Universe at a Time is to convey an understanding of our Universe in a way that is honest and free of hype. Modern astrophysics is complex, and the conclusions we can draw from our findings is often subtle. One Universe at a Time focuses on peer-reviewed evidence to present our best current knowledge. When there is scientific controversy, various views will be discussed.
One Universe at a Time
1d ago
Avi Loeb/The Galileo Project A 0.4-millimeter diameter iron-rich spherule.
Our solar system does not exist in isolation. It formed within a stellar nursery along with hundreds of sibling stars, and even today has the occasional interaction with interstellar objects such as Oumuamua and Borisov. So it’s reasonable to presume that some interstellar material has reached Earth. Recently Avi Loeb and his team earned quite a bit of attention with a study arguing that it had found some of this interstellar stuff on the ocean seabed.1 But a new study finds that the material has a much more local origi ..read more
One Universe at a Time
6d ago
NASA A pair of disc galaxies in the late stages of a merger.
The Universe is filled with supermassive black holes. Almost every galaxy in the cosmos has one, and they are the most well-studied black holes by astronomers. But one thing we still don’t understand is just how they grew so massive so quickly. To answer that, astronomers have to identify lots of black holes in the early Universe, and since they are typically found in merging galaxies, that means astronomers have to identify early galaxies accurately. By hand. But thanks to the power of machine learning, that’s changing.1
With the po ..read more
One Universe at a Time
1w ago
University of Warwick/Mark Garlick Artist illustration of crystals forming within a white dwarf.
At the end of their lives, most stars including the Sun will become white dwarfs. After a red dwarf or sun-like star consumes all the hydrogen and helium it can, the remains of the star will collapse under its own weight, shrinking ever more until the quantum pressure of electrons becomes strong enough to counter gravity. White dwarfs begin their days as brilliantly hot embers of degenerate matter and grow ever cooler and dimmer as they age.
Because a white dwarf doesn’t produce new energy through ..read more
One Universe at a Time
1w ago
ESO/M. Kornmesser An artistic impression adapted to highlight gas dispersing from a planet-forming disk.
Nearly 5 billion years ago a region of gas gravitationally collapsed within a vast molecular cloud. At the center of the region, the Sun began to form, while around it formed a protoplanetary disk of gas and dust out of which Earth and the other planets of the solar system would form. We know this is how the solar system began because we have observed this process in systems throughout the galaxy. But there are details of the process we still don’t understand, such as why gas planets are re ..read more
One Universe at a Time
1w ago
ESO/L. Calçada This artist’s impression shows the magnetic white dwarf WD 0816-310.
Nothing is immortal. Everything has a finite existence, including the stars themselves. How a star dies depends on several factors, most importantly their mass. For the Sun, this means that in several billion years it will swell to a red giant as it churns through the last of its nuclear fuel. The core that remains will then collapse to become a white dwarf. Of course, the Sun is home to several planets, including Earth. What of their fate? What of ours? According to a recent study, the Sun’s death might consum ..read more
One Universe at a Time
1w ago
ESO/M. Kornmesser This artist’s impression shows dust forming in the environment around a supernova explosion.
Life on our planet appeared early in Earth’s history. Surprisingly early, since in its early youth our planet didn’t have much of the chemical ingredients necessary for life to evolve. Since prebiotic chemicals such as sugars and amino acids are known to appear in asteroids and comets, one idea is that Earth was seeded with the building blocks of life by early cometary and asteroid impacts. While this likely played a role, a new study shows that cosmic dust also seeded young Earth, an ..read more
One Universe at a Time
3w ago
C. Padilla, NRAO/AUI/NSF The Atacama Large Millimeter/submillimeter Array (ALMA).
The conditions for life throughout the Universe are so plentiful that it seems reasonable to presume there must be extra-terrestrial civilizations in the galaxy. But if that’s true, where are they? The Search for Extra-terrestrial Intelligence (SETI) program and others have long sought to find signals from these civilizations, but so far there has been nothing conclusive. Part of the challenge is that we don’t know what the nature of an alien signal might be. It’s a bit like finding a needle in a haystack when yo ..read more
One Universe at a Time
3w ago
One of the central predictions of general relativity is that in the end, gravity wins. Stars will fuse hydrogen into new elements to fight gravity and can oppose it for a time. Electrons and neutrons exert pressure to counter gravity, but their stability against that constant pull limits the amount of mass a white dwarf or neutron star can have. All of this can be countered by gathering more mass together. Beyond about 3 solar masses, give or take, gravity will overpower all other forces and collapse the mass into a black hole.
While black holes have a great deal of theoretical and observation ..read more
One Universe at a Time
3w ago
Southwest Research Institute Illustration of the icy dwarf planets Eris and Makemake.
Whether or not you agree that Pluto isn’t a planet, in many ways, Pluto is quite different from the classical planets. It’s smaller than the Moon, has an elliptical orbit that brings it closer to the Sun than Neptune at times, and is part of a collection of icy bodies on the edge of our solar system. It was also thought to be a cold dead world until the flyby of New Horizons proved otherwise. The plucky little spacecraft showed us that Pluto was geologically active, with a thin atmosphere and mountains that r ..read more
One Universe at a Time
1M ago
ESA/Euclid/Euclid Consortium The areas that the space telescope Euclid will observe.
On July 1, 2023, the Euclid Spacecraft launched with a clear mission: to map the dark and distant Universe. To achieve that goal, over the next 6 years, Euclid will make 40,000 observations of the sky beyond the Milky Way. From this data astronomers will be able to map the positions of billions of galaxies, allowing astronomers to observe the effects of dark matter.
There have been several galactic sky surveys before, but Euclid’s mission will take them to the next level. Euclid is equipped with a widefield im ..read more