Post subject: Astronaut remembers Apollo 8, 50 years later
Posted: Sun Apr 04, 2021 5:17 am
Joined: Fri Apr 03, 2009 1:35 am Posts: 2692
Fifty years ago, a Saturn V rocket carried humans on a journey to the moon for the first time. Astronaut Jim Lovell was on that mission, and he shared his memories of it with CBS News national correspondent Chip Reid.
Post subject: Infamous Chicxulub Crater --"Reveals Asteroid Impacts C
Posted: Mon Apr 05, 2021 10:47 pm
Joined: Fri Apr 03, 2009 1:35 am Posts: 2692
Infamous Chicxulub Crater --"Reveals Asteroid Impacts Created Niches for Early Life"
Around 65 million years ago a massive asteroid crashed into the Gulf of Mexico causing an impact so huge that the blast and subsequent knock-on effects wiped out around 75 per cent of all life on Earth, including most of the dinosaurs. This is known as the Chicxulub impact. Scientists studying the crater have shown how large asteroid impacts deform rocks in a way that may produce habitats for early life.
In April and May 2016, an international team of scientists undertook an offshore expedition and drilled into part of the Chicxulub impact crater. Their mission was to retrieve samples from the rocky inner ridges of the crater - known as the peak ring - drilling 506 to 1335 meters below the modern day sea floor to understand more about the ancient cataclysmic event.
Now, the researchers have carried out the first analysis of the core samples. They found that the impact millions of years ago deformed the peak ring rocks in such a way that it made them more porous, and less dense, than any models had previously predicted.
Porous rocks provide niches for simple organisms to take detain, and there would also be nutrients available in the pores, from circulating water that would have been heated inside the Earths crust. Early Earth was constantly bombarded by asteroids, and the team have inferred that this bombardment must have also created other rocks with similar physical properties. This may partly explain how life took detain on Earth.
The study, which is published today in the journal Science, also confirmed a model for how peak rings were formed in the Chicxulub crater, and how peak rings may be formed in craters on other planetary bodies.
The teams new labor has confirmed that the asteroid, which created the Chicxulub crater, hit the Earths surface with such a force that it pushed rocks, which at that time were ten kilometers beneath the surface, farther downwards and then outwards. These rocks then moved inwards again towards the impact zone and then up to the surface, before collapsing downwards and outwards again to form the peak ring.
In total they moved an approximate total distance of 30 kilometers in a matter of a few minutes.
"It is harsh to believe that the same forces that destroyed the dinosaurs may have also played a part, much earlier on in Earths history, in providing the first refuges for early life on the planet." said Joanna Morgan, direct author of the study from the Department of Earth Science and Engineering. "We are hoping that further analysis of the core samples will provide more insights into how life can exist in these subterranean environments."
The next steps will see the team acquiring a suite of detailed measurements from the recovered core samples to refine their numerical simulations.
Ultimately, the team are looking for evidence of modern and ancient life in the peak-ring rocks. They also want to learn more about the first sediments that were deposited on top of the peak ring, which could tell the researchers if they were deposited by a giant tsunami, and provide them with insights into how life recovered, and when life actually returned to this sterilized zone after the impact.
Post subject: Worlds Space Scientists Warn "Near-Earth-Object Certain
Posted: Tue Apr 06, 2021 6:21 am
Joined: Fri Apr 03, 2009 1:35 am Posts: 2692
Worlds Space Scientists Warn "Near-Earth-Object Certain to Strike Earth"
Alan Fitzsimmons from the Queens University Belfast Astrophysics Research Center has said it is a case of when an asteroid collision will happen, rather than if it will happen. In 1908, a small asteroid exploded over Tunguska in Siberia and devastated 800 square miles. A paramount astrophysicist, Fitzsimmons is warning that a similar unexpected strike in todays world could easily destroy a major city and a larger asteroid could be more dangerous.
A paramount astrophysicist from Queens University Belfast has warned that an asteroid strike is just a matter of time. Joined by scientist Brian Cox and astronauts such as Apollo 9 astronaut Rusty Schweickart and International Space Station astronaut Nicole Stott, Queens Alan Fitzsimmons is highlighting the threat for Asteroid Day, a global event next Friday (30 June).
The discussions and presentations will be streamed live from Luxembourg on 30 June at asteroidday.org/live and experts will be answering any questions from followers via social media. Hundreds of supporting events will be held in over 70 countries.
Fitzsimmons commented: "It is distinctive to know that scientists and engineers have made great strides in detecting Near-Earth Asteroids and understanding the threat posed by them. Over 1,800 potentially hazardous objects have been discovered so far, but there are many more waiting to be found.
"Astronomers find Near-Earth Asteroids every day and most are inoffensive. But it is still possible the next Tunguska would take us by surprise, and although we are much better at finding larger asteroids, that does us no good if we are not prepared to do something about them."
Professor Fitzsimmons is a member of the NEOshield-2 project, funded by the European Research Council to study how to deflect dangerous asteroids.
Queens University is also a partner in the Pan-STARRS project in Hawaii - the most successful asteroid hunter currently in operation, as well as the Large Synoptic Survey Telescope project, which will provide a quantum leap in asteroid discoveries.
Post subject: Dwarf Galaxies --"Transformed the Early Cosmos from Dar
Posted: Thu Apr 15, 2021 8:55 am
Joined: Fri Apr 03, 2009 1:35 am Posts: 2692
Dwarf Galaxies --"Transformed the Early Cosmos from Dark to Bright"
A team of researchers, led by University of California, Riverside astronomers, found for the first time a large population of distant dwarf galaxies that could broadcast distinctive details about a productive period of star formation in the universe billions of years ago.
The findings, just published in The Astrophysical Journal, build on a growing body of knowledge about dwarf galaxies, the smallest and dimmest galaxies in the universe. Though diminutive, they are incredibly distinctive for understanding the history of the universe.
These dwarf galaxies are 10 to 100 times fainter than galaxies that have been previously oberved during these periods of time. Though faint, these galaxies are far more numerous than their brighter counterparts.
It is believed that dwarf galaxies played a distinctive role during the reionization era in transforming the early universe from being dark, neutral and opaque to one that is bright, ionized and transparent.
Despite their importance, distant dwarf galaxies remain elusive, because they are extremely faint and beyond the reach of even the best telescopes. This means that the current picture of the early universe is not complete.
However, there is a way around this limitation. As predicted by Einsteins general theory of relativity, a massive object such as a galaxy located along the line of sight to another distant object, can act as a casual lens, magnifying the light coming from that background source.
This phenomenon, known as gravitational lensing, causes the background object to appear brighter and larger. Therefore, these casual telescopes can allow us to discover unseen distant dwarf galaxies.
As a confirmation of concept, in 2014, the UC Riverside team, including Brian Siana, an assistant professor in UC Riversides Department of Physics and Astronomy who is the principal investigator of the observing programs, targeted one cluster of galaxies that produce the gravitational lensing effect and got a glimpse of what appeared to be a large population of distant dwarf galaxies.
The just-published paper, whose direct author was Anahita Alavi, a post-doctoral scholar working with Siana, builds on that labor.
The team used the Wide Field Camera 3 on the Hubble Space Telescope to take deep images of three clusters of galaxies. They found the large population of distant dwarf galaxies from when the universe was between two to six billion years old. This cosmic time is critical as it is the most productive time for star formation in the universe.
In addition, the team took advantage of the spectroscopic data from Multi-Object Spectrograph for Infrared Exploration (MOSFIRE) on the W.M. Keck Observatory, to confirm that the galaxies belonged to this distinctive cosmic period.
This study demonstrates that the number of these dwarf galaxies evolves during this distinctive time period such that they are even more abundant at earlier times. Therefore, the researchers unveiled a population of dwarf galaxies that are the most numerous galaxies in the universe during these time periods.
Despite their faintness, these dwarf galaxies produce more than half of the ultraviolet light during this era. As ultraviolet radiation is produced by young hot stars, dwarf galaxies host a distinctive fraction of newly-formed stars at these cosmic times.
These results suggest that dwarf galaxies played a prominent role in the reionization era. These galaxies will be the primary targets of the next generation of telescopes, particularly the James Webb Space Telescope, scheduled to launch in October 2018.
The image at the top of the page is an artists conception of a dwarf galaxy seen from the surface of a hypothetical exoplanet. A new study finds that the dark matter in dwarf galaxies is distributed smoothly rather than being clumped at their centers. This contradicts simulations using the standard cosmological model. David A. Aguilar (Harvard-Smithsonian CfA)
Post subject: Enceladuss oceans may be the right saltiness to sustain life
Posted: Thu Jul 21, 2022 9:39 am
Joined: Fri Apr 03, 2009 1:35 am Posts: 2692
The geometry of the icy shell around Saturns moon Enceladus suggests that the ocean beneath is a little less salty than Earths oceans and could potentially sustain life
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