Subscribe to our weekly newsletter
Science confirms: Earth has more than one 'moon'
Two massive clouds of dust in orbit around the Earth have been discussed for years and finally proven to exist.
- Hungarian astronomers have proven the existence of two "pseudo-satellites" in orbit around the earth.
- These dust clouds were first discovered in the sixties, but are so difficult to spot that scientists have debated their existence since then.
- The findings may be used to decide where to put satellites in the future and will have to be considered when interplanetary space missions are undertaken.
After more than fifty years of stargazing, debate, and controversy, scientists have confirmed the existence of two "moons" or "pseudo-satellites" made of dust orbiting the Earth. Though the clever use of mathematics, they also argue that the location of these dust clouds gives them some unique characteristics.
What are they?
Artist's impression of the Kordylewski cloud in the night sky (with its brightness greatly enhanced) at the time of the observations.
The Kordylewski clouds are two dust clouds first observed by Polish astronomer Kazimierz Kordylewski in 1961. They are situated at two of the Lagrange points in Earth's orbit. These points are locations where the gravity of two objects, such as the Earth and the Moon or a planet and the Sun, equals the centripetal required to orbit the objects while staying in the same relative position. There are five of these spots between the Earth and Moon. The clouds rest at what are called points four and five, forming a triangle with the clouds and the Earth at the three corners.
The clouds are enormous, taking up the same space in the night sky as twenty lunar discs; covering an area of 45,000 miles. They are roughly 250,000 miles away, about the same distance from us as the Moon. They are entirely comprised of specks of dust which reflect the light of the sun so faintly most astronomers that looked for them were unable to see them at all.
The clouds themselves are probably ancient, but the model that the scientists created to learn about them suggests that the individual dust particles that comprise them can be blown away by solar wind and replaced by the dust from other cosmic sources like comet tails. This means that the clouds hardly move but are eternally changing.
How did they discover this?
"In this picture the central region of the Kordylewski dust cloud is visible (bright red pixels). The straight tilted lines are traces of satellites."
In their study published in the Monthly Notices of the Royal Astronomical Society, Hungarian astronomers Judit Slíz-Balogh, András Barta, and Gábor Horváth described how they were able to find the dust clouds using polarized lenses.
Since the clouds were expected to polarize the light that bounces off of them, by configuring the telescopes to look for this kind of light the clouds were much easier to spot. What the scientists observed, polarized light in patterns that extended outside the view of the telescope lens, was in line with the predictions of their mathematical model and ruled out other possible sources.
Why are we just learning this now?
"Mosaic pattern of the angle of polarization around the L5 point (white dot) of the Earth-Moon system. The five rectangular windows correspond to the imaging telescope with which the patterns of the Kordylewski cloud were measured."
The objects, being dust clouds, are very faint and hard to see. While Kordylewski observed them in 1961, other astronomers have looked there and given mixed reports over the following decades. This discouraged many astronomers from joining the search, as study co-author Judit Slíz-Balogh explained, "The Kordylewski clouds are two of the toughest objects to find, and though they are as close to Earth as the Moon are largely overlooked by researchers in astronomy. It is intriguing to confirm that our planet has dusty pseudo-satellites in orbit alongside our lunar neighbor."
Will this have any impact on space travel?
Lagrange points have been put forward as excellent locations for a space station or satellites like the James Webb Telescope to be put into orbit, as they would require little fuel to stay in place. Knowing about a massive dust cloud that could damage sensitive equipment already being there could save money and lives in the future. While we only know about the clouds at Lagrange points four and five right now, the study's authors suggest there could be more at the other points.
While the discovery of a couple of dust clouds might not seem all that impressive, it is the result of a half-century of astronomical and mathematical work and reminds us that wonders are still hidden in our cosmic backyard. While you might never need to worry about these clouds again, there is nothing wrong with looking at the sky with wonder at the strange and fantastic things we can discover.
A Mercury-bound spacecraft's noisy flyby of our home planet.
- There is no sound in space, but if there was, this is what it might sound like passing by Earth.
- A spacecraft bound for Mercury recorded data while swinging around our planet, and that data was converted into sound.
- Yes, in space no one can hear you scream, but this is still some chill stuff.
First off, let's be clear what we mean by "hear" here. (Here, here!)
Sound, as we know it, requires air. What our ears capture is actually oscillating waves of fluctuating air pressure. Cilia, fibers in our ears, respond to these fluctuations by firing off corresponding clusters of tones at different pitches to our brains. This is what we perceive as sound.
All of which is to say, sound requires air, and space is notoriously void of that. So, in terms of human-perceivable sound, it's silent out there. Nonetheless, there can be cyclical events in space — such as oscillating values in streams of captured data — that can be mapped to pitches, and thus made audible.
Image source: European Space Agency
The European Space Agency's BepiColombo spacecraft took off from Kourou, French Guyana on October 20, 2019, on its way to Mercury. To reduce its speed for the proper trajectory to Mercury, BepiColombo executed a "gravity-assist flyby," slinging itself around the Earth before leaving home. Over the course of its 34-minute flyby, its two data recorders captured five data sets that Italy's National Institute for Astrophysics (INAF) enhanced and converted into sound waves.
Into and out of Earth's shadow
In April, BepiColombo began its closest approach to Earth, ranging from 256,393 kilometers (159,315 miles) to 129,488 kilometers (80,460 miles) away. The audio above starts as BepiColombo begins to sneak into the Earth's shadow facing away from the sun.
The data was captured by BepiColombo's Italian Spring Accelerometer (ISA) instrument. Says Carmelo Magnafico of the ISA team, "When the spacecraft enters the shadow and the force of the Sun disappears, we can hear a slight vibration. The solar panels, previously flexed by the Sun, then find a new balance. Upon exiting the shadow, we can hear the effect again."
In addition to making for some cool sounds, the phenomenon allowed the ISA team to confirm just how sensitive their instrument is. "This is an extraordinary situation," says Carmelo. "Since we started the cruise, we have only been in direct sunshine, so we did not have the possibility to check effectively whether our instrument is measuring the variations of the force of the sunlight."
When the craft arrives at Mercury, the ISA will be tasked with studying the planets gravity.
The second clip is derived from data captured by BepiColombo's MPO-MAG magnetometer, AKA MERMAG, as the craft traveled through Earth's magnetosphere, the area surrounding the planet that's determined by the its magnetic field.
BepiColombo eventually entered the hellish mangentosheath, the region battered by cosmic plasma from the sun before the craft passed into the relatively peaceful magentopause that marks the transition between the magnetosphere and Earth's own magnetic field.
MERMAG will map Mercury's magnetosphere, as well as the magnetic state of the planet's interior. As a secondary objective, it will assess the interaction of the solar wind, Mercury's magnetic field, and the planet, analyzing the dynamics of the magnetosphere and its interaction with Mercury.
Recording session over, BepiColombo is now slipping through space silently with its arrival at Mercury planned for 2025.
Research suggests that aging affects a brain circuit critical for learning and decision-making.
As people age, they often lose their motivation to learn new things or engage in everyday activities. In a study of mice, MIT neuroscientists have now identified a brain circuit that is critical for maintaining this kind of motivation.
Researchers develop the first objective tool for assessing the onset of cognitive decline through the measurement of white spots in the brain.
- MRI brain scans may show white spots that scientists believe are linked to cognitive decline.
- Experts have had no objective means of counting and measuring these lesions.
- A new tool counts white spots and also cleverly measures their volumes.
White spots and educated guesses<p>The white spots, or "hyperintensities," are brain lesions—fluid-filled holes in the brain believed to have been left behind by the breaking down of blood vessels that had previously provided nourishment to brain cells.</p><p>Prior to the new research, the quantity of white spots was assessed using an imprecise three-point scale indicating ascending likelihoods of dementia: A minimal number of spots was considered as level 1, a medium number of spots level 2, and a great number of them level 3.</p>
How the new measurements were derived<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDYwMTc1OS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYzNDQ1ODExNX0.vqhQJSvL99KjOe24TOs4E8R7c6-pprbXYSrGcIqbVps/img.jpg?width=980" id="c64d9" class="rm-shortcode" data-rm-shortcode-id="002d9b8ef47b5a86c3a387ad2cd90629" data-rm-shortcode-name="rebelmouse-image" />
Credit: sfam_photo/Shutterstock<p>The team of researchers from NYU's Langone's <a href="https://med.nyu.edu/departments-institutes/neurology/divisions-centers/center-cognitive-neurology" target="_blank">Center for Cognitive Neurology</a> and <a href="https://med.nyu.edu/departments-institutes/neurology/divisions-centers/center-cognitive-neurology/alzheimers-disease-research-center" target="_blank">Alzheimer's Disease Research Center</a> were led by <a href="https://med.nyu.edu/faculty/jingyun-chen" target="_blank">Jingyun "Josh" Chen</a>. They analyzed 72 MRI scans from a national database of older people taken as part of the <a href="http://adni.loni.usc.edu" target="_blank">Alzheimer's Disease Neuroimaging Initiative</a> (ADNI). The scans were mostly of white people over age 70, and there were a roughly equivalent number of men and women. Some had normal brain function, some were presenting moderate cognitive decline, and some had severe dementia.</p><p>Without knowing each individual's diagnosis, the researchers analyzed the white spots in their scans. While the team counted each scan's lesions, the innovation they introduced was the production of a 3D measurement for each lesion's fluid volume. The measurement was derived by measuring a lesion's distance from opposite sides of the brain.</p><p>Measurements of 0 milliliters (mL) were assessed for areas without white spots, with other white spots coming up as containing 60 mL of fluid. Chen's team predicted that volumes over 100 mL could signify severe dementia.</p><p>"Amounts of white matter lesions above the normal range should serve as an early warning sign for patients and physicians," Chen told <a href="https://nyulangone.org/news/white-matter-lesion-mapping-tool-identifies-early-signs-dementia" target="_blank">NYU Langone Health NewsHub</a>.</p><p>When the team compared the likely diagnoses derived from their calculations against the individuals' medical records, they found that their predictions were correct about 7 out of 10 times.</p><p>The researchers compiled their formulas into an online tool that's available to physicians for free via <a href="https://github.com/jingyunc/wmhs" target="_blank" rel="noopener noreferrer">GitHub</a>. The researchers plan to further refine and test it using an additional 1,495 brain scans representing a more diverse group of individuals from the ADNI database.</p>