Science
Astronomers analyze first results from ESO telescopes on the aftermath of DART’s asteroid impact
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Using ESO’s Very Large Telescope (VLT), two teams of astronomers have observed the aftermath of the collision between NASA’s Double Asteroid Redirection Test (DART) spacecraft and the asteroid Dimorphos. The controlled impact was a test of planetary defense, but also gave astronomers a unique opportunity to learn more about the asteroid’s composition from the expelled material.
On September 26, 2022, the DART spacecraft collided with the asteroid Dimorphos in a controlled test of our asteroid deflection capabilities. The impact took place 11 million kilometers away from Earth, close enough to be observed in detail with many telescopes. All four 8.2-meter telescopes of ESO’s VLT in Chile observed the aftermath of the impact, and the first results of these VLT observations have now been published in two papers.
“Asteroids are some of the most basic relics of what all the planets and moons in our solar system were created from,” says Brian Murphy, a Ph.D. student at the University of Edinburgh in the UK and co-author of one of the studies. “Studying the cloud of material ejected after DART’s impact can therefore tell us about how our solar system formed.”
“Impacts between asteroids happen naturally, but you never know it in advance,” continues Cyrielle Opitom, an astronomer also at the University of Edinburgh and lead author of one of the articles. “DART is a really great opportunity to study a controlled impact, almost as in a laboratory.”
Opitom and her team followed the evolution of the cloud of debris for a month with the Multi Unit Spectroscopic Explorer (MUSE) instrument at ESO’s VLT. They found that the ejected cloud was bluer than the asteroid itself was before the impact, indicating that the cloud could be made of very fine particles. In the hours and days that followed the impact other structures developed: clumps, spirals and a long tail pushed away by the sun’s radiation. The spirals and tail were redder than the initial cloud, and so could be made of larger particles.
MUSE allowed Opitom’s team to break up the light from the cloud into a rainbow-like pattern and look for the chemical fingerprints of different gases. In particular, they searched for oxygen and water coming from ice exposed by the impact. But they found nothing.
“Asteroids are not expected to contain significant amounts of ice, so detecting any trace of water would have been a real surprise,” explains Opitom. They also looked for traces of the propellant of the DART spacecraft, but found none. “We knew it was a long shot,” she says, “as the amount of gas that would be left in the tanks from the propulsion system would not be huge. Furthermore, some of it would have traveled too far to detect it with MUSE by the time we started observing.”
Another team, led by Stefano Bagnulo, an astronomer at the Armagh Observatory and Planetarium in the UK, studied how the DART impact altered the surface of the asteroid.
“When we observe the objects in our solar system, we are looking at the sunlight that is scattered by their surface or by their atmosphere, which becomes partially polarized,” explains Bagnulo. This means that light waves oscillate along a preferred direction rather than randomly. “Tracking how the polarization changes with the orientation of the asteroid relative to us and the sun reveals the structure and composition of its surface.”
Bagnulo and his colleagues used the FOcal Reducer/low dispersion Spectrograph 2 (FORS2) instrument at the VLT to monitor the asteroid, and found that the level of polarization suddenly dropped after the impact. At the same time, the overall brightness of the system increased. One possible explanation is that the impact exposed more pristine material from the interior of the asteroid.
“Maybe the material excavated by the impact was intrinsically brighter and less polarizing than the material on the surface, because it was never exposed to solar wind and solar radiation,” says Bagnulo.
Another possibility is that the impact destroyed particles on the surface, thus ejecting much smaller ones into the cloud of debris. “We know that under certain circumstances, smaller fragments are more efficient at reflecting light and less efficient at polarizing it,” explains Zuri Gray, a Ph.D. student also at the Armagh Observatory and Planetarium.
The studies by the teams led by Bagnulo and Opitom show the potential of the VLT when its different instruments work together. In fact, in addition to MUSE and FORS2, the aftermath of the impact was observed with two other VLT instruments, and analysis of these data is ongoing.
“This research took advantage of a unique opportunity when NASA impacted an asteroid,” concludes Opitom, “so it cannot be repeated by any future facility. This makes the data obtained with the VLT around the time of impact extremely precious when it comes to better understanding the nature of asteroids.”
The research highlighted in the first part of this article was presented in the paper “Morphology and spectral properties of the DART impact ejecta with VLT/MUSE,” which appears in Astronomy & Astrophysics. The second part of this article refers to the paper “Optical spectropolarimetry of binary asteroid Didymos-Dimorphos before and after the DART impact” in Astrophysical Journal Letters.
More information:
C. Opitom et al, Morphology and spectral properties of the DART impact ejecta with VLT/MUSE, Astronomy & Astrophysics (2023). DOI: 10.1051/0004-6361/202345960
Optical spectropolarimetry of binary asteroid Didymos-Dimorphos before and after the DART impact, Astrophysical Journal Letters (2023). DOI: 0.3847/2041-8213/acb261. iopscience.iop.org/article/10. … 847/2041-8213/acb261
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Citation:
Astronomers analyze first results from ESO telescopes on the aftermath of DART’s asteroid impact (2023, March 21)
retrieved 21 March 2023
from https://phys.org/news/2023-03-astronomers-results-eso-telescopes-aftermath.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.
Science
Solar eclipse April 8 – South Grey News
March 28, 2024
Graphic: Appalachian Mtn Club
Grey Bruce Public Health is urging residents to resist the temptation to look directly at the sun during the upcoming solar eclipse and take steps to safeguard their visual health during this relatively rare celestial event.
On April 8, 2024, parts of southern and eastern Ontario will experience a total solar eclipse for the first time since 1925. Grey-Bruce will be outside of the so-called Path of Totality — a narrow area where the moon will completely block out the sun — but will still experience a partial eclipse.
The eclipse is expected to begin at about 2 pm and continue until 4:30 pm The eclipse will peak around 3:20 pm.
It is never safe to stare directly at the sun, but it may be tempting to do so during a solar eclipse.
Looking directly at the sun during an eclipse can cause retinal burns, blurred vision, and/or temporary or permanent loss of visual function, according to the Ontario Association of Optometrists. Damage to the eyes can occur without any sensation of pain.
Grey Bruce Public Health advises the following:
- Do not look directly at the sun without proper eye protection during the solar eclipse. Looking at even a small sliver of the sun before or after the eclipse without proper eye protection can harm vision.
- Keep a close eye on children and other vulnerable family members during the eclipse to ensure they do not inadvertently look up at the sun without proper eye protection.
- To safely view the eclipse, ISO-certified eclipse glasses that meet the ISO 12312-2 international safety standard must be worn. Ensure these glasses are in good condition, without any wrinkles or scratches, and that they fully cover the entire field of vision. Put on the glasses when looking away from the sun, then look at the eclipse. Look away from the sun before taking the glasses off.
- Regular sunglasses or homemade filters will not protect the eyes.
- It is not safe to view the eclipse through a camera/phone lens, telescope, binoculars, or any other optical device.
Other ways to safely experience the solar eclipse include watching a livestream of the event or creating and using an eclipse box or pinhole projector.
Anyone experiencing temporary vision loss or blurred vision during or after the eclipse should speak with their eye care professional or healthcare provider as soon as possible.
Anyone experiencing blindness (immediate or delayed) after viewing the eclipse must seek emergency care immediately.
More information on the upcoming eclipse is available on the GBPH website.
At South Grey News, we endeavour to bring you truthful and factual, up-to-date local community news in a quick and easy-to-digest format that’s free of political bias. We believe this service is more important today than ever before, as social media has given rise to misinformation, largely unchecked by big corporations who put profits ahead of their responsibilities.
South Grey News does not have the resources of a big corporation. We are a small, locally owned-and-operated organization. Research, analysis and physical attendance at public meetings and community events requires considerable effort. But contributions from readers and advertisers, however big or small, go a long way to helping us deliver positive, open and honest journalism for this community.
Please consider supporting South Grey News with a donation in lieu of a subscription fee and let us know that our efforts are appreciated. Thank you.
Science
NASA to launch sounding rockets into moon's shadow during solar eclipse – Phys.org
NASA will launch three sounding rockets during the total solar eclipse on April 8, 2024, to study how Earth’s upper atmosphere is affected when sunlight momentarily dims over a portion of the planet.
The Atmospheric Perturbations around Eclipse Path (APEP) sounding rockets will launch from NASA’s Wallops Flight Facility in Virginia to study the disturbances in the ionosphere created when the moon eclipses the sun. The sounding rockets had been previously launched and successfully recovered from White Sands Test Facility in New Mexico, during the October 2023 annular solar eclipse.
They have been refurbished with new instrumentation and will be relaunched in April 2024. The mission is led by Aroh Barjatya, a professor of engineering physics at Embry-Riddle Aeronautical University in Florida, where he directs the Space and Atmospheric Instrumentation Lab.
The sounding rockets will launch at three different times: 45 minutes before, during, and 45 minutes after the peak local eclipse. These intervals are important to collect data on how the sun’s sudden disappearance affects the ionosphere, creating disturbances that have the potential to interfere with our communications.
The ionosphere is a region of Earth’s atmosphere that is between 55 to 310 miles (90 to 500 kilometers) above the ground. “It’s an electrified region that reflects and refracts radio signals and also impacts satellite communications as the signals pass through,” said Barjatya. “Understanding the ionosphere and developing models to help us predict disturbances is crucial to making sure our increasingly communication-dependent world operates smoothly.”
The ionosphere forms the boundary between Earth’s lower atmosphere—where we live and breathe—and the vacuum of space. It is made up of a sea of particles that become ionized, or electrically charged, from the sun’s energy or solar radiation.
When night falls, the ionosphere thins out as previously ionized particles relax and recombine back into neutral particles. However, Earth’s terrestrial weather and space weather can impact these particles, making it a dynamic region and difficult to know what the ionosphere will be like at a given time.
It’s often difficult to study short-term changes in the ionosphere during an eclipse with satellites because they may not be at the right place or time to cross the eclipse path. Since the exact date and times of the total solar eclipse are known, NASA can launch targeted sounding rockets to study the effects of the eclipse at the right time and at all altitudes of the ionosphere.
As the eclipse shadow races through the atmosphere, it creates a rapid, localized sunset that triggers large-scale atmospheric waves and small-scale disturbances or perturbations. These perturbations affect different radio communication frequencies. Gathering the data on these perturbations will help scientists validate and improve current models that help predict potential disturbances to our communications, especially high-frequency communication.
The APEP rockets are expected to reach a maximum altitude of 260 miles (420 kilometers). Each rocket will measure charged and neutral particle density and surrounding electric and magnetic fields. “Each rocket will eject four secondary instruments the size of a two-liter soda bottle that also measure the same data points, so it’s similar to results from fifteen rockets while only launching three,” explained Barjatya. Embry-Riddle built three secondary instruments on each rocket, and the fourth one was built at Dartmouth College in New Hampshire.
In addition to the rockets, several teams across the U.S. will also be taking measurements of the ionosphere by various means. A team of students from Embry-Riddle will deploy a series of high-altitude balloons. Co-investigators from the Massachusetts Institute of Technology’s Haystack Observatory in Massachusetts and the Air Force Research Laboratory in New Mexico will operate a variety of ground-based radars taking measurements.
Using this data, a team of scientists from Embry-Riddle and Johns Hopkins University Applied Physics Laboratory are refining existing models. Together, these various investigations will help provide the puzzle pieces needed to see the bigger picture of ionospheric dynamics.
When the APEP-sounding rockets launched during the 2023 annular solar eclipse, scientists saw a sharp reduction in the density of charged particles as the annular eclipse shadow passed over the atmosphere.
“We saw the perturbations capable of affecting radio communications in the second and third rockets, but not during the first rocket that was before peak local eclipse,” said Barjatya. “We are super excited to relaunch them during the total eclipse to see if the perturbations start at the same altitude and if their magnitude and scale remain the same.”
The next total solar eclipse over the contiguous U.S. is not until 2044, so these experiments are a rare opportunity for scientists to collect crucial data.
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Citation:
NASA to launch sounding rockets into moon’s shadow during solar eclipse (2024, March 27)
retrieved 28 March 2024
from https://phys.org/news/2024-03-nasa-rockets-moon-shadow-solar.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.
Science
Royal Sask. Museum research finds insect changes may have set stage for dinosaurs' extinction – CTV News Regina
Research by the Royal Saskatchewan Museum (RSM) shows that ecological changes were occurring in insects at least a million years before dinosaur extinction.
Papers published in the scientific journal, Current Biology, describe the first insect fossils found in amber from Saskatchewan and the unearthing of three new ant species from an amber deposit in North Carolina, according to a release from the province.
The amber deposit from in the Big Muddy Badlands of Saskatchewan, which was formed about 67 million years ago, preserved insects that lived in a swampy redwood forest about one million years before the extinction of dinosaurs.
“Fossils in the amber deposit seem to show that common Cretaceous insects may have been replaced on the landscape by their more modern relatives, particularly in groups such as ants, before the extinction event,” Elyssa Loewen, curatorial assistant, said.
The research team was led by Loewen and Dr. Ryan McKellar, the RSM’s curator of paleontology.
“These new fossil records are closer than anyone has gotten to sampling a diverse set of insects near the extinction event, and they help researchers fill in a 17-million-year gap in the fossil record of insects around that time,” Dr. McKellar said.
The three ant species discovered in North Carolina also belonged to extinct groups that didn’t survive past the Cretaceous period.
“When combined with the work in Saskatchewan, the two recent papers show that there was a dramatic change in ant diversity sometime between 77 and 67 million years ago,” Dr. McKellar said in the release.
“Our analyses of body shapes in the fossils suggests that the turnover was not related to major differences in ecology, but it may have been related to something like the size and complexity of ant colonies. More work is needed to confirm this.”
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