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A foot-shaped piece of flotsam has caused confusion among forensic scientists – but Feedback is relieved that the matter was cleared up thanks to that old stalwart, "examination"

From chess to nuclear war planning, Kelly Clancy takes a wide-ranging look at how games and gaming have changed society in Playing With Reality

From chess to nuclear war planning, Kelly Clancy takes a wide-ranging look at how games and gaming have changed society in Playing With Reality

Creating "walled gardens", much like TV channels do, would provide children better tools to navigate a lifetime of social media than banning smartphones altogether

Creating "walled gardens", much like TV channels do, would provide children better tools to navigate a lifetime of social media than banning smartphones altogether

New research shows that the speed of sound on Mars varies considerably by location and temperature. The findings could help scientists understand sounds picked up by Martian rovers, as well as make future crewed ventures safer.

Places beset by heat waves should receive FEMA disaster funds just as those hit by hurricanes or flooding do, labor unions, green groups and public health advocates argue in a new petition

There’s no perfect way of doing anything, including searching for exoplanets. Every planet-hunting method has some type of bias. We’ve found most exoplanets using the transit method, which is biased toward larger planets. Larger planets closer to their stars block more light, meaning we detect large planets transiting in front of their stars more readily than we detect small ones.

That’s a problem because some research says that life-supporting planets are more likely to be small, like Earth. It’s all because of moons and streaming instability.

Consider Earth’s Moon. While there’s no consensus on every aspect of the Moon and its role, there’s evidence that it helps make life on Earth possible and has helped life sustain itself for so long. As natural satellites go, it’s massive. Of the approximately 300 (and counting) moons in our Solar System, the Moon is the fifth largest. But that doesn’t tell the tale of its relationship with our planet.

The Moon’s diameter is about one-quarter of Earth’s diameter, and its mass is about 1.2% of Earth’s. The four natural satellites in the Solar System that are larger than the Moon orbit the gas giants Jupiter and Saturn. Those moons are tiny compared to their planets.

This means that the Moon has different effects on Earth than other moons do on their planets.

The Moon stabilizes Earth’s orbital tilt, which helps keep the climate stable and allows life to flourish and organisms to adapt. It creates tides, which may have played a role in the formation of nucleic acids and life. The Moon may even help Earth maintain its protective magnetosphere. One way or another, Earth would be a very different place without its huge Moon.

New research published in The Planetary Science Journal shows that we should look for small planets if we want to find life-supporting worlds because small planets are more likely to host larger moons. The research is titled “The Limited Role of the Streaming Instability during Moon and Exomoon Formation.” The lead author is Miki Nakajima, an Assistant Professor of Earth and Environmental Sciences at Rochester University.

“Relatively small planets similar to the size of Earth are more difficult to observe and they have not been the major focus of the hunt for moons,” said lead author Nakajima. “However, we predict these planets are actually better candidates to host moons.”

The leading theory for the Moon’s formation is the Giant Impact Hypothesis. It states that when the Earth was very young, about 4.5 billion years ago, a Mars-sized protoplanet named Theia slammed into Earth. The collision created a rotating torus of molten rock that orbited the Earth. Some fell back down to Earth, and the rest coalesced into the Moon. There’s still a lot of debate over this, but it is the leading theory.

Here’s where streaming instability comes in.

This research questions the role of streaming instability in moon formation. Some scientists think that planet formation is the same as moon formation. However, while streaming instability is important for planet formation, it may not be for the formation of large moons like Earth’s, which help make planets habitable.

In their research, Nakajima and her colleagues used simulations to examine the role of streaming instability in moon formation. Streaming instability describes the effect that drag has on the accretion of matter in a protoplanetary disk that leads to planetesimals. Inside a disk, drag rapidly drives solid particles to concentrate spontaneously into clumps. These clumps can then collapse and form planetesimals.

The question is, does streaming instability play the same role in the formation of moons around planets? In this case, the disk isn’t a protoplanetary disk but a disk of debris resulting from a collision.

“Here, we investigate the effect of the streaming instability in the Moon-forming disk for the first time and find that this instability can quickly form ~100 km-sized moonlets,” the authors write in their paper. “However, these moonlets are not large enough to avoid strong drag, and they still fall onto Earth quickly.”

“These moonlets could grow further once the disk cools enough and the vapor mass fraction of the disk becomes small,” the researchers write in their article. “However, by this time a significant amount of the disk mass is lost, and the remaining disk could make only a small moon.”

This figure from the research shows four snapshots from the simulations. At t = 2.87, streaming instability starts to form clumps. Gravity is turned on at t = 3.18, and by t = 3.39 and 3.55, moonlets start to form by gravitational instability. Image Credit: Nakajima et al. 2024.

For a large moon like Earth’s to form, the collision has to be less energetic than one between much more massive planets. If Theia had been more massive, the heat from the impact would’ve created a completely vapourized disk. Only a much smaller moon could’ve formed in such a disk.

This figure from the research shows how long moonlets can reside in a disk before crashing into their planet. The two lines show the cases of an icy planet collision and a rocky planet collision. The x-axis shows the planet’s mass, and the y-axis shows time in days. Since the moonlets can’t stay in the disk for long, it indicates that “streaming instability likely plays a limited role in impact-induced moon-forming disks,” as the authors explain. Image Credit: Nakajima et al. 2024.

The researchers think that streaming instability may not help large moons form in vapour-rich disks. Fractionally large moons like Earth’s Moon, which may be necessary for life, might only form in vapour-poor disks. More massive planets have more energetic collisions, which creates vapour-rich disks. Smaller planets have vapour-poor disks where larger moons can form.

This graphic from the research illustrates the researchers’ hypothesis. It shows how only small moons form in vapour-rich disks from energetic impacts. Streaming instability plays a small role in forming moons in impact-induced disks because they’re vapour-rich. Image Credit: Nakajima et al. 2024.

So, if we want to find life-supporting planets, look for small worlds where larger moons are more likely to form.

“We find a limited role of streaming instability in satellite formation in an impact-induced disk, whereas it plays a key role during planet formation,” the authors conclude.

The post If We Want To Find Life-Supporting Worlds, We Should Focus on Small Planets With Large Moons appeared first on Universe Today.

Unique cell responses mean some people may be immune to catching the coronavirus, even if they are unvaccinated

Unique cell responses mean some people may be immune to catching the coronavirus, even if they are unvaccinated

A material made of liquid salt mixed with polymers is extremely stretchy but still as strong as the plastics used to make water bottles

A material made of liquid salt mixed with polymers is extremely stretchy but still as strong as the plastics used to make water bottles

Summer will officially arrive in the Northern Hemisphere on Thursday (June 20) at 4:51 p.m. EDT (2051 GMT) — the June Solstice. Here's what you need to know.

The New Horizons mission to Pluto, now zooming out of the Kuiper belt, has made a discovery that could upend what we know about where the solar system ends

The New Horizons mission to Pluto, now zooming out of the Kuiper belt, has made a discovery that could upend what we know about where the solar system ends

A giant flower, one of the smelliest in the world, is currently blooming at the Royal Botanic Gardens, Kew

A giant flower, one of the smelliest in the world, is currently blooming at the Royal Botanic Gardens, Kew

A major lunar standstill is about to occur. The phenomenon happens every 18.6 years when the moon rises and sets at its most extreme points on the horizon, while also climbing to its highest and lowest point in the sky.

Studying the history of science shows how often serendipity plays a role in some of the most important discoveries. Sometimes, the stories are apocryphal, like Newton getting hit on the head with an apple. But sometimes, there’s an element of truth to them. That was the case for a new discovery of the oldest pair of merging quasars ever discovered – and it all started with a pair of red blots on a picture.

Those red blots were on a very particular picture – one taken by the Hyper Subprime-Cam on the Subaru telescope in Manuakea, Hawai’i. Yoshiki Matsuoka of Ehime University in Japan, who was manually reviewing the picture with colleagues, noticed two faint red splotches. Unlike an automated algorithm, which might have overlooked them, he was interested in what might have caused them and decided to look closer.

To do so, he recruited another instrument on the Subaru telescope, known as the Faint Object Camera and Spectrograph, and the Gemini Near-Infrared Spectrograph on the neighboring Gemini North telescope. After combing through this more targeted data, Dr. Matsuoka and his colleagues found something no one had seen before—a pair of merging quasars from less than a billion years after the universe was created.

Fraser explains what a quasar is, and why they’re so important.

Quasar mergers were theorized to happen all the time during that period, but despite having found 300 separate quasars around the same time frame, astronomers had yet to find any pairs. This was important because that time period, known as the Epoch of Reionization, was key in creating the structure of the modern-day universe.

During the Epoch of Reionization, energy, potentially from merging quasars, stripped the free-floating hydrogen abundant in the early universe of its electrons in a process called ionization. Around 1 billion years after the Big Bang and the theoretical end of the Epoch of Reionization, the structure of the modern universe was largely settled, and it had officially moved out of the period known as the “cosmic dark ages.” 

Understanding this period is critical for theorizing how the universe formed. Astronomers had long thought that merging quasars would have been common in the period, as supermassive black holes were relatively close, and structures were still working themselves out. So, the lack of them in experimental data was concerning. 

Quasars aren’t only ancient history – could our own supermassive black hole at the center of the Milky Way become one?

Enter the pair found by Dr. Matsuoka and his colleagues. They appear about 900 million years after the Big Bang, still well within the Epoch of Reionization. However, collecting data on them wasn’t easy, as old objects suffer from contamination in their signals, such as gravitational lensing and stars in the foreground. The researchers eventually found that some of the optical light wasn’t directly coming from the quasars but rather the formation of stars around them.

However, the quasars were massive behemoths, weighing over 100 million times more than our Sun. They also had a bridge of gas connecting them, implying that the two galaxies they formed the core of were undergoing a massive merger, which we will now get to observe as it happens. 

That merger is going to take millions, if not billions, of years, though, so it might be some time before we see the full effect. But in the meantime, cosmologists can start studying this quasar pair in earnest to see what other details can be gleaned about the Epoch of Reionization or the formation of the universe more generally. And it will all happen because someone noticed some red blots on a picture and decided to investigate it further.

Learn More:
NOIRLab – International Gemini Observatory and Subaru Combine Forces to Discover First Ever Pair of Merging Quasars at Cosmic Dawn
Matsuoka et al – Discovery of Merging Twin Quasars at z = 6.05
UT – Hubble Sees Two Quasars Side by Side in the Early Universe
UT – The James Webb Is Getting Closer to Finding What Ionized the Universe

Lead Image:
Illustration of merging quasars
Credit – NOIRLab/NSF/AURA/M. Garlick

The post The Earliest Merging Quasars Ever Seen appeared first on Universe Today.

The face of summer is transforming, as people today face more frequent, longer-lasting and hotter heat waves than they did several decades ago