Universe Today

December 21, 2023December 21, 2023 by Nancy Atkinson

Finally. A Productive Use for Nuclear Weapons: Asteroid Defense

Four different asteroids and how nuclear ablation affects asteroids of different makeups. — A modeling tool developed by scientists at Lawrence Livermore National Laboratory shows the progression an asteroid being broken up by a theoretical nuclear device detonated near the the surface of the near-Earth object. Graphic illustration courtesy of Mary Burkey.

While it has been a favorite disaster movie theme, nuking an incoming asteroid in the real world has been touted as a very bad idea. While a nuclear bomb could possibly obliterate a smaller asteroid, nuking a larger asteroid would only break it into pieces. Those pieces would still threaten our planet, and perhaps even makes things worse by producing multiple impacts across the planet.

But is using nuclear weapons on an incoming asteroid really a bad idea? If the right technique is used, a nuclear blast could possibly be used as an asteroid deflection device.

December 21, 2023December 18, 2023 by Paul M. Sutter

Why the Universe Might be a Hologram

The colored circle represents the hologram, out of which the knotted optical vortex emerges. Credit: University of Bristol

A quarter century ago, physicist Juan Maldacena proposed the AdS/CFT correspondence, an intriguing holographic connection between gravity in a three-dimensional universe and quantum physics on the universe’s two-dimensional boundary. This correspondence is at this stage, even a quarter century after Maldacena’s discovery, just a conjecture. A statement about the nature of the universe that seems to be true, but one that has not yet been proven to actually reflect the reality that we live in. And what’s more, it only has limited utility and application to the real universe.

December 20, 2023December 21, 2023 by Matt Williams

It Doesn't Take Much to Get a Runaway Greenhouse Effect

During the 1960s, the first robotic explorers began making flybys of Venus, including the Soviet Venera 1 and the Mariner 2 probes. These missions dispelled the popular myth that Venus was shrouded by dense rain clouds and had a tropical environment. Instead, these and subsequent missions revealed an extremely dense atmosphere predominantly composed of carbon dioxide. The few Venera landers that made it to the surface also confirmed that Venus is the hottest planet in the Solar System, with average temperatures of 464 °C (867 °F).

These findings drew attention to anthropogenic climate change and the possibility that something similar could happen on Earth. In a recent study, a team of astronomers from the University of Geneva (UNIGE) created the world’s first simulation of the entire greenhouse process that can turn a temperate planet suitable for Life into a hellish, hostile one. Their findings revealed that on Earth, a global average temperature rise of just a few tens of degrees (coupled with a slight rise in the Sun’s luminosity) would be sufficient to initiate this phenomenon and render our planet uninhabitable.

December 20, 2023December 21, 2023 by Nancy Atkinson

Enjoy the Holiday-Themed Christmas Tree Cluster

The Christmas Tree Cluster, (NGC 2264). Credit: X-ray: NASA/CXC/SAO; Optical: T.A. Rector (NRAO/AUI/NSF and NOIRLab/NSF/AURA) and B.A. Wolpa (NOIRLab/NSF/AURA); Infrared: NASA/NSF/IPAC/CalTech/Univ. of Massachusetts; Image Processing: NASA/CXC/SAO/L. Frattare & J.Major

Just in time for the holidays, a new composite image of the Christmas Tree Cluster (NGC 2264) has been released. This image is a group effort: the blue and white stars in the cluster giving off X-rays are seen by Chandra, while the faint green nebula was imaged by the WIYN 0.9-meter telescope on Kitt Peak.

December 20, 2023December 21, 2023 by Andy Tomaswick

Astronomers Find the Birthplaces of Stars in the Whirlpool Galaxy

Understanding how star-forming works at a galactic scale is challenging in our Milky Way. While we have a general understanding of the layout of our galaxy, we can’t see all of the details head-on like we would want to if we were exploring a single galaxy for details of star formation. Luckily, we have a pretty good view of the entirety of one of the most famous galaxies in all of astronomy – M51, the Whirlpool Galaxy. Now, a team of researchers from the Max Planck Institute for Astronomy has completed a survey of molecules throughout the galaxy and developed a map of potential star-forming regions.

December 20, 2023December 21, 2023 by Paul M. Sutter

The Strangest Coincidence in Physics: The AdS/CFT Correspondence

The west limb of the Sun imaged by NuSTAR and SDO shows areas of high-energy x-rays above particularly active regions (NASA/JPL-Caltech/GSFC)

Attempts to turn string theory into a workable theory of nature have led to the potential conclusion that our universe is a hologram: that what we perceive as three spatial dimensions is actually composed of only two. The greatest realization of this hologram-led program is a proposal that goes by the awkward and clunky name of the AdS/CFT correspondence, first proposed by string theorist Juan Maldacena in the late 1990’s.

December 20, 2023December 20, 2023 by Andy Tomaswick

A New View of Uranus’ North Pole from JWST

One cool thing about Uranus is that its orientation, compared to the rest of the solar system, allows a unique perspective of the planet from our home planet. It is tilted at 98° compared to the rest of the ecliptic plane. So, when viewed from Earth, we can see its North Pole and its rings in some exceptional cases. That perspective is fully displayed in an image of Uranus recently released by the European Space Agency (ESA) and captured using the James Webb Space Telescope (JWST).

December 19, 2023December 19, 2023 by Nancy Atkinson

Blue Origin’s New Shepard Completes 24th Flight; New Glenn Hopefully on the Horizon

New Shepard’s booster lands on the pad during NS-24 on December 19, 2023. Credit: Blue Origin.

Blue Origin’s New Shepard rocket successfully launched and landed today at the company’s Launch Site One in West Texas, with an uncrewed science and goodwill payload onboard. This was the 24th New Shepard flight and 13th payload mission today from Launch Site One in West Texas.

This marked the first flight since September of 2022 when the uncrewed NS-23’s booster suffered an in-flight anomaly; however, the escape system jettisoned the capsule, which was able to land safely. With the success of NS-24, Blue Origin hopes to soon restart its commercial passenger flights.

December 19, 2023December 19, 2023 by Evan Gough

Can Webb Find the First Stars in the Universe?

The Universe’s very first stars had an important job. They formed from the primordial elements created by the Big Bang, so they contained no metals. It was up to them to synthesize the first metals and spread them out into the nearby Universe.

The JWST has made some progress in finding the Universe’s earliest galaxies. Can it have the same success when searching for the first stars?

December 19, 2023December 19, 2023 by Andy Tomaswick

Astronomers Find Two Planetary Systems Around Sun-Like Stars

NASA’s Transiting Exoplanet Survey Satellite (TESS) has been busy. Clocking in over 5000 exoplanet candidates, the researchers who manage the telescope’s data have enlisted an army of volunteer classifiers to sift through its data to confirm whether these planets exist. In a new paper in Astronomy & Astrophysics, some researchers from Brazil think they have found three planets that almost certainly do – and they happen to orbit stars that are very similar to our own Sun.