Galaxy Express
One Universe at a Time
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2d 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
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Beast Stars
One Universe at a Time
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5d 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
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The Outer Worlds
One Universe at a Time
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5d 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
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To Map the Distant Heavens
One Universe at a Time
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1w 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
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The Power of Magnetism
One Universe at a Time
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1w ago
NASA/JPL-Caltech Artist’s concept of a magnetar. Fast radio bursts (FRBs) are strange events. They can last only milliseconds, but during that time can outshine a galaxy. Some FRBs are repeaters, meaning that they can occur more than once from the same location, while others seem to occur just once. We still aren’t entirely sure what causes them, or even if the two types have the same cause. But thanks to a collaboration of observations from ground-based radio telescopes and space-based X-ray observatories, we are starting to figure FRBs out. Most FRBs happen well beyond our galaxy, so while w ..read more
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Change of Plans
One Universe at a Time
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1w ago
José A. Peñas/SINC Scholz’s Star seen from Earth 70,000 years ago. The orbit of Earth around the Sun is always changing. It doesn’t change significantly from year to year, but over time the gravitational tugs of the Moon and other planets cause Earth’s orbit to vary. This migration affects Earth’s climate. For example, the gradual shift of Earth’s orbit and the changing tilt of Earth’s axis leads to the Milankovitch climate cycles. So if you want to understand paleoclimate or the shift of Earth’s climate across geologic time, it helps to know what Earth’s orbit was in the distant past. Fortuna ..read more
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Fast and Far
One Universe at a Time
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1w ago
NAOC FAST catches a real pulse from FRB 121102. Now and then there is a bright radio flash somewhere in the sky. It can last anywhere from a few milliseconds to a few seconds. They appear somewhat at random, and we still aren’t sure what they are. We call them fast radio bursts (FRBs). Right now the leading theory is that they are caused by highly magnetic neutron stars known as magnetars. With observatories such as CHIME we are now able to see lots of them, which could give astronomers a new way to measure the rate of cosmic expansion.1 The rate of cosmic expansion is described by the Hubble ..read more
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Jets on the Edge
One Universe at a Time
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1w ago
Georgios Filippos Paraschos (MPIfR) The jet of the black hole in 3C 84 at different spatial scales. Although supermassive black holes are common throughout the Universe, we don’t have many direct images of them. The problem is that while they can have a mass of millions or billions of stars, even the nearest supermassive black holes have tiny apparent sizes. The only direct images we have are those of M87* and Sag A*, and it took a virtual telescope the size of Earth to capture them. But we are still in the early days of the Event Horizon Telescope (EHT), and improvements are being made to the ..read more
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Discovering Life on Planet Earth
One Universe at a Time
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2w ago
NASA/JPL An image of Earth taken by the Galileo spacecraft in 1990. In the Fall of 1989, the Galileo spacecraft was launched into space, bound for Jupiter and its family of moons. Given the great distance to the king of planets, Galileo had to take a roundabout tour through the inner solar system, making a flyby of Venus in 1990 and Earth in 1990 and 1992 just to gain enough speed to reach Jupiter. During the flybys of Earth Galileo took several images of our planet, which astronomers have used to discover life on Earth.1 The idea of “discovering” life on Earth in the 21st century might seem a ..read more
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The Dust of Time
One Universe at a Time
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2w ago
NASA, ESA and the Hubble Heritage (STScI/AURA)-ESA/Hubble A dusty spiral galaxy known as M66. Astronomers have many ways to measure the distance to galaxies billions of light years away, but most of them rely upon standard candles. These are astrophysical processes that have a brightness we can calibrate, such as Cepheid variable stars or Type Ia supernovae. Of course, all of these standard candles have some inherent variability, so astronomers also look for where our assumptions about them can lead us astray. As a case in point, a recent study in The Astrophysical Journal shows how galactic d ..read more
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