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Fri, 09 Dec 2022
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Comets


Doberman

1 dead, 1 hurt in dog attacks in West Memphis, Arkansas

dog attack
A man was killed and a woman badly injured by a pack of dogs in two separate attacks in West Memphis, Arkansas.

READ: https://wreg.com/news/local/dog-pack-...


Popcorn

Cryovolcanic eruption on comet 29P/Schwassmann-Wachmann reported

comet 29P/Schwassmann-Wachmann
The British Astronomical Association (BAA) is reporting a new outburst of cryovolcanic comet 29P/Schwassmann-Wachmann. On Nov. 22nd, amateur astronomer Patrick Wiggins watched 29P increase in brightness by more than 4 magnitudes--a sign that a major eruption was in progress. On Nov. 23rd, André Debackère used the Faulkes Telescope North in Hawaii to photograph the expanding shell of debris:

The Pac-Man shape of the ejecta shows that this is not a uniform global eruption. Instead, it is coming from one or more discrete sources on the comet's surface.

This fits a leading model of the comet developed by Dr. Richard Miles of the British Astronomical Association. Miles believes that 29P is festooned with ice volcanoes. There is no lava. The "magma" is a cold mixture of liquid hydrocarbons (e.g., CH4, C2H4, C2H6 and C3H8) akin to those found in lakes and streams on Saturn's moon Titan. The cryomagma is suffused with dissolved gases N2 and CO, much like carbonation in a soda bottle. These bottled-up volatiles love to explode when a fissure is opened by the warming action of sunlight.

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Fireball 5

New research reveals space debris, invisible meteors and near-Earth asteroids

In a new thesis from the Swedish Institute of Space Physics and Umeå University, unique methods for the analysis of radar data and simulations of meteoroids in the solar system are presented. The methods have been applied to confirm the existence of rare high-altitude meteors as well as to measure space debris from the Kosmos-1408 satellite. On November 25, Daniel Kastinen defends his doctoral thesis.
Daniel Kastinen
© Martin Eriksson / Daniel Kastinen (illustration
Daniel Kastinen's thesis presents results that pave the way for future research and cross-disciplinary studies on meteors as well as on space debris and near-Earth asteroids.
"My primary goal has been to carefully analyze radar measurements of meteors and space debris and evaluate the precision of the measurements. This is to improve further analysis and use the results together with the new dynamical simulations. The work paves the way for future research and allows cross-disciplinary studies on meteors as well as on space debris and near-Earth asteroids", says Daniel Kastinen.

Every day, 10-200 tons of material from space, consisting of dust- sized particles and larger pieces of material - meteoroids, fall into the Earth's atmosphere. These particles come from parent bodies such as comets and asteroids and thus date back to the time when the solar system was formed. When a meteoroid hits the Earth's atmosphere and burns up in the form of a meteor, the material is dispersed in the atmosphere. Most of these meteors are invisible to the eye but can be detected by radar.

Arrow Up

'Planet killer' asteroid found hiding in sun's glare may one day threaten Earth

"Only about 25 asteroids with orbits completely within Earth's orbit have been discovered to date because of the difficulty of observing near the glare of the sun."

Asteroid behind Sun
© DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA/J. da Silva/Spaceengine
Asteroids in the inner system are notoriously hard to detect because of the glare of the sun.
Astronomers have discovered a giant asteroid hiding in the glare of the sun that might one day cross paths with Earth

The 0.9-mile-wide (1.5 kilometers) asteroid is the largest potentially hazardous asteroid spotted in the past eight years and astronomers have dubbed it a "planet killer" because the effects of its impact would be felt across multiple continents.

The asteroid, named 2022 AP7, managed to avoid detection for so long because it orbits in the region between Earth and Venus. To spot space rocks in this area, astronomers have to look in the direction of the sun, and that is notoriously difficult due to the sun's luminosity. For example, flagship telescopes such as the James Webb Space Telescope and the Hubble Space Telescope never look toward the sun, as the star's brightness would fry their sensitive optics.

Because of that, astronomers have only a limited understanding of the nature of asteroids lurking in this region, and sometimes, surprises may happen. In 2013, a much smaller asteroid, only 66 feet wide (20 m), arrived from the direction of the sun completely without warning. That asteroid exploded above the city of Chelyabinsk in southeastern Russia, shattering windows on thousands of buildings.

Fireball 5

Large, 'potentially hazardous' asteroid will zip through Earth's orbit on Halloween

The asteroid's upper size estimate is just short of the world's tallest building.
Asteroid
© Science Photo Library - ANDRZEJ WOJCICKI via Getty Images
An artist's impression of a near-Earth asteroid.
A newly discovered, "potentially hazardous" asteroid almost the size of the world's tallest skyscraper is set to tumble past Earth just in time for Halloween, according to NASA.

The asteroid, called 2022 RM4, has an estimated diameter of between 1,083 and 2,428 feet (330 and 740 meters) — just under the height of Dubai's 2,716-foot-tall (828 m) Burj Khalifa, the tallest building in the world. It will zoom past our planet at around 52,500 mph (84,500 km/h), or roughly 68 times the speed of sound.

At its closest approach on Nov. 1, the asteroid will come within about 1.43 million miles (2.3 million kilometers) of Earth, around six times the average distance between Earth and the moon. By cosmic standards, this is a very slender margin.

NASA flags any space object that comes within 120 million miles (193 million km) of Earth as a "near-Earth object" and classifies any large body within 4.65 million miles (7.5 million km) of our planet as "potentially hazardous." Once flagged, these potential threats are closely watched by astronomers, who study them with radar for signs of any deviation from their predicted trajectories that could put them on a devastating collision course with Earth.

Info

Fireball from Solar System's edge isn't what astronomers expected

Asteroid Comet
© ISTOCK / GETTY IMAGES
This stock image shows a comet hurtling through space, with an inset of a map of Canada. Scientists recently found that a space rock that lit up the skies over Canada in February 2021 wasn't actually a comet.
Just before dawn on 22 February 2021, a fireball lit up the skies across Canada's Alberta (see video below) province when a 2-kilogram space rock vaporized as it plunged through Earth's atmosphere. Although the object hailed from the Oort Cloud — a conglomeration of comets at the edge of the Solar System — it wasn't a comet, researchers now say. Data collected during its fall suggest the object was made of rock rather than ice and behaved more like an asteroid.

Independent observers of the new work say the find sheds light on the processes that formed our Solar System and challenges the conventional wisdom that the Oort Cloud only holds icy comets. "It's telling us that there was scattering and depositing of material from all over the Solar System into the Oort Cloud," says Karen Meech, a planetary scientist at the University of Hawaii's Institute for Astronomy.

The discovery could provide support for models that suggest objects from the asteroid belt were dispersed into the Oort Cloud soon after the Solar System's birth 4.6 billion years ago, says Bill Bottke, a Solar System dynamicist at the Southwest Research Institute. "This is very exciting," he says. "Now, we have to see what we can do to explain it."

First proposed by Dutch astronomer Jan Oort in 1950, the Oort Cloud is a spherical halo of comets that stretches out halfway to Proxima Centauri, the Sun's nearest neighbor, well beyond the view of even the largest telescopes. "Everything we know about it is indirect," says Denis Vida, a meteor astronomer at Western University who led the new study.

Scientists presume the Oort Cloud became populated with comets when the gravitational muscle of Jupiter and the other giant planets scattered far and wide the icy objects that were leftover from the formation of the outer Solar System. Occasionally, a passing star will gravitationally nudge an Oort Cloud object and send it plummeting into the inner Solar System. These objects are known as long-period comets, defined by their eccentric paths that take hundreds or even thousands of years to orbit the Sun.

Comet 2

30,000 near-Earth asteroids discovered, and rising - ESA

Asteroid Eros

Asteroid Eros, as seen by NEAR Shoemaker
We have now discovered 30,039 near-Earth asteroids in the Solar System - rocky bodies orbiting the Sun on a path that brings them close to Earth's orbit. The majority of these were discovered in the last decade, showing how our ability to detect potentially risky asteroids is rapidly improving.

In-depth What is a near-Earth asteroid?

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Fireball

First probable impact crater discovered in Spain

Impact Crater Spain
© Sánchez-Garrido et al 2022. Basemap: Instituto Geográfico Nacional (IGN). License: CC-BY 4.0.
Location of the crater centre and 20 kilometre radius of the area affected by the impact in the Alhabia-Tabernas basin.
The first probable impact crater in Spain has been identified in the southern province of Almeria. The discovery was presented last week at the Europlanet Science Congress (EPSC) 2022 by Juan Antonio Sánchez Garrido of the University of Almeria.

While around 200 impact structures have been identified around the world, the study is the first to identify signs of an impact crater on the Iberian Peninsula. The discovery is the result of 15 years of research by an international team of scientists from the University of Almeria, the Astrobiology Center of Madrid, the University of Lund and the University of Copenhagen.

Prof Sánchez Garrido said: "We believe that the impact event occurred around 8 million years ago. We have investigated numerous aspects of the geology, minerology, geochemistry and geomorphology of the region. The basins of Alhabia and Tabernas in the area are filled with sediments dating back between 5 and 23 million years, and they overlie older metamorphic rocks. Much of the impact structure is buried by more modern sediments, but erosion has exposed it and opened up the opportunity for studies."

The crater itself is thought to be about 4 kilometres in diameter, and it is surrounded by a larger structure about 20 kilometres across where the impact caused the sedimentary strata to collapse.

Comet 2

NASA's DART anti-asteroid satellite successfully smashes into space rock

Asteroid Didymos (top left) and its moonlet, Dimorphos
© Nasa
NASA has completed a key step of its "Double Asteroid Redirection Test" (DART), smashing a satellite roughly the size of a vending machine into a small moon that's about half-a-mile in diameter. The moon, Dimorphos, is orbiting an even larger asteroid, Didymos, and while neither is in any danger of colliding with Earth, they're good test cases to see whether us puny humans smashing them with technology can cause them to change course.

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Info

Scientists shine light on 66-million-year-old meteorite wildfire mystery

Impact Study
© compiled by Vellekoop et al
(A) location map of the study area. (B) paleogeographic reconstruction of Gulf of Mexico and Baja California Pacific margin taken from Stéphan et al, and Helenes & Carreño, with location of this study, Chicxulub crater, and impact-related slumps, faults, slides, and tsunami deposits.
The meteorite that wiped out Earth's dinosaurs instantly ignited forest wildfires up to thousands of kilometres from its impact zone, scientists have discovered.

The six-mile-wide meteorite struck the Yucatan peninsula in what is now Mexico at the end of the Cretaceous Period 66 million years ago, triggering a mass extinction that killed off more than 75 percent of living species.

Uncertainty and debate have surrounded the circumstances behind the devastating wildfires known to have been caused by the strike, with several theories as to how and when they started, and their full extent.

By analysing rocks dating to the time of the strike, a team of geoscientists from the UK, Mexico and Brazil has recently discovered that some of the fires broke out within minutes, at most, of the impact, in areas stretching up to 2500km or more from the impact crater.

Wildfires that broke out in coastal areas were short-lived, as the backwash from the mega-tsunami caused by the impact swept charred trees offshore.