More than 5,000 tonnes of space dust hit Earth every year
If you’ve ever seen a shooting star, you’ve encountered a bit of space dust – interplanetary particles leftover from comets and asteroids that burn up when they enter Eath’s atmosphere. Some of this dust reaches the ground as “micrometeorites”, which can be just a few tenths to a few hundredths of a millimetre across.
Over the last two decades, an international team of scientists has been on the hunt for these micrometeorites. They undertook six expeditions to the Franco-Italian Concordia station in central Antarctica, collecting enough of these tiny particles from the pristine snow to estimate that across the whole planet, 5,200 tonnes rain down every year.
Their analysis, published in the journal Earth & Planetary Science Letters, also suggests that about 80% micrometeorites originate from comets.
Drones could be used to ethically herd sheep
A paper by the University of New South Wales has suggested that drones may be better shepherds than traditional methods.
The study, published in Scientific Reports, described an autonomous system that uses AI to consider the welfare of the sheep, reducing stress on the animal.
“UAVs are currently being used by farmers, so this isn’t a brand-new school of thought,” says Squadron Leader Kate Yaxley, a Visiting Military Fellow at UNSW Canberra and one of the lead researchers on the study.
“But what we found was missing was that there was no understanding of how the sheep are interacting with the technology and the impact of the technology on their welfare.”
“What we found through this study is that the sheep had higher heart rates when they’re being shepherded by traditional means. So, the simple act of moving them to another paddock for food is actually putting the animal under stress.”
“We measured the variations in their heart rates, and we found it to be much lower when using UAVs with appropriate approach speed, and that the animals actually responded to the technology. If we played certain sounds that allowed them to use their sensors, their aural and visual acuity, they moved a lot easier.
“This is part of our research that is continuing at the moment. In addition to this, we’re focusing on the frequency of the sounds emitted as opposed to trying to emit a particular sound.”
Giant radio pulses more giant than astronomers thought
At the heart of the Crab Nebula, the husk of a dead star spins more than 30 times per second. This super-dense star corpse is a pulsar. It emits violent jets of particles at nearly the speed of light – including bursts of radio waves just a few milliseconds in duration, known as “giant radio pulses”.
Astronomers studying this pulsar have just observed that its giant radio pulses are accompanied by an increase in X-ray emissions, suggesting that the pulses are hundreds of times more energetic than previously believed. The observations were made by simultaneously peering at the Crab Nebula with both ground-based radio observatories in Japan and a space-based X-ray-detecting instrument on the International Space Station.
Giant radio pulses have been observed coming from a dozen pulsars across the galaxy, but what causes them is little understood – some astronomers have proposed that they might be the origin of the elusive “fast radio bursts”.
According to the study’s lead author, Teruaki Enoto from the RIKEN Cluster for Pioneering Research in Japan, “the relationship between the two is still controversial, and these findings, along with upcoming discoveries regarding fast radio bursts, will help us to understand the relationship between these phenomena”.
The study is published in Science.
Examining the mystery of sea turtle migrations
Ecologists know a lot about sea turtle behaviour on the coasts of Japan and Baja California, because it’s easier to study things on land. But little is understood about the turtles’ journey across the Pacific Ocean between the two coasts.
Now, research published in Frontiers in Marine Science explains part of this migration, suggesting that warm ocean currents allow the turtles to cross typically cold and inhospitable areas.
“For decades, our ability to connect the migratory dots for this endangered species has remained elusive,” said study lead author Dana Briscoe, who was a research associate at the Stanford Woods Institute for the Environment during the research and now works at the Cawthron Institute in New Zealand. “This work builds on the backbone of exceptional research about these ‘lost years,’ and for the first time ever we are excited to provide evidence of a ‘thermal corridor’ to explain a longstanding mystery of one of the ocean’s greatest migrants.”