Solar System – astroengine.com

Earth’s Magnetic Field Just Hit a Phantom Speed Bump

Earth likely passed through “a fold in the heliospheric current sheet,” which induced a powerful electrical surge down here on the ground.

While science news is filled with rumbling earthquakes and rippling gravitational waves, a different kind of perturbation was felt in Norway yesterday (Jan. 6)—but its cause is a little mysterious.

“Electrical currents started flowing,” said Rob Stammes, of the Polarlightcenter geophysical observatory in Lofoten, Norway, in a report by Spaceweather.com.

A shockwave in magnetometer data and a surge in ground currents indicated that the magnetosphere had interacted with the interplanetary magnetic field (IMF) [Rob Stammes/Polarlightcenter/Spaceweather.com]

Stammes monitors the flow of electricity through the ground and compares it with the wiggles of the Earth’s magnetic field (as plotted above). These two key measurements allow space weather scientists to better understand how our planet’s magnetosphere is being affected by the magnetic field of our Sun and how it may impact our everyday lives.

While the Sun-Earth relationship is well studied, usually magnetospheric jiggles are associated with obvious (and often explosive) solar phenomena, such as coronal mass ejections (CMEs) and powerful solar wind flows. Yesterday, however, at around 1930 UT, our magnetosphere was jolted by a phantom event.

It was as if Earth orbited through an invisible magnetic speed bump.

Before we can understand what this means (and, indeed, why it’s important), let’s take a quick trip to the biggest magnetic dynamo in the Solar System.

As you can see, the Sun isn’t currently all that active [NASA/SDO]

You know it as the giant orb of superheated plasma that gives life to Earth and dazzles you during your commute home from work, but the Sun also has an invisible magnetic dominance over all the planets. Extending from the solar interior to well beyond the orbit of Pluto, the Sun’s magnetic field creates a vast magnetic bubble called the heliosphere. Carried by the solar wind, this magnetism spirals out, through interplanetary space, interacting with any other magnetic field it may come across. In the case of our planet, our global magnetic field (the magnetosphere) is generated by the constant sloshing of molten iron in Earth’s core. Our magnetosphere reaches out into interplanetary space and, like a forcefield, it deflects the highly energetic plasma (consisting mainly of protons and some highly ionized particles) sloughing from our Sun. There’s a constant magnetic battle raging over our heads; the Sun’s magnetic field washes over our protective magnetosphere, which acts like a sea wall protecting the coastline from an unrelenting stormy ocean.

Now, if the conditions are right, the Sun’s magnetic field may breach Earth’s magnetosphere, causing the two to snap and reconnect, effectively creating a temporary magnetic marriage between the Sun and Earth. When this happens, a magnetic highway for solar particles is formed, injecting the layers of our magnetosphere with solar plasma. Ultimately, this plasma can stream along our planet’s magnetic field (or get trapped and stored), creating auroras in higher latitudes and generate electrical currents through the atmosphere and surface.

The Earth’s magnetic field warps and bends, deflecting highly energetic solar particles. But sometimes, the shield is breached, often with dramatic effect. [NASA]

Usually, space weather forecasters use a plethora of instruments to predict when this might happen. For example, they may detect a CME erupt on the corona, predict its speed, and then register a flip in the interplanetary magnetic field (IMF) by a satellite between us and the Sun (such as NASA’s Advanced Composition Explorer, or ACE, which is located at the Sun-Earth L1 point, nearly a million miles “upstream” toward the Sun). But, in the case of yesterday’s mysterious event in Norway, there was no warning for the magnetic breach in our magnetosphere. No CME, no visible increase in solar wind intensity; just a magnetic blip from ACE and a shockwave sent ripping through magnetometer stations on the ground followed by a surge in electricity through our planet’s surface.

We’d been suckerpunched by the Sun’s magnetism, but there was no obvious fist. To confirm the sudden magnetic blow (called a geomagnetic storm), magnificent auroras erupted over the poles.

So, what happened? There is a theory:

Earth may have crossed through a fold in the heliospheric current sheet—a giant, wavy membrane of electrical current rippling through the solar system. Such crossings can cause these kind of effects.
Tony Phillips, Spaceweather.com

Looking like the warped disk of an old vinyl record, the heliospheric current sheet ripples throughout the solar system. As Earth rotates around the Sun, it will pass through the “surface” of this sheet, where the magnetic polarity of the IMF will rapidly change. And this is probably what happened yesterday. As the Earth orbited through a fold in the sheet, the magnetic polarity flipped 180 degrees, creating the phantom interaction with our magnetosphere. This, in turn, released solar particles that had been trapped in the layers of our magnetosphere, causing them to surge through the upper atmosphere, creating an intense—and surprise—auroral display.

Predicting when these events are going to occur is critical to space weather prediction efforts. As demonstrated by Stammes’ measurements of currents flowing through the ground, geomagnetic storms can overload national power grids, leaving entire nations (or, potentially, entire continents) in the dark.

While this Norway event didn’t cause reported damage to any infrastructure, it is a reminder that our planet’s interactions with the solar magnetic field—and subsequent impacts to our civilization—can be unpredictable and, in this case, invisible.

Interstellar Comet Borisov Looks Weirdly Familiar

The gas cyanogen has been detected in 2I/Borisov’s coma—a historic detection of a gas commonly found in regular comets.

Artist’s impression of a cometary nucleus. [ESA]

It’s official, the solar system is playing host to its second confirmed interstellar visitor only two years after the strangely-shaped `Oumuamua was spotted receding into interstellar expanse. While `Oumuamua was historic in that it was the first confirmed interstellar comet to be discovered, according to a new study (which has yet to be peer reviewed), this newest interstellar vagabond is potentially more significant:

“For the first time we are able to accurately measure what an interstellar visitor is made of, and compare it with our own solar system,” said Alan Fitzsimmons of the Astrophysics Research Center, Queen’s University Belfast, in a statement.

So, why are astronomers so excited about 2I/Borisov?

A (Cometary) Star Is Born

In late August, the comet was discovered by Gennady Borisov, an amateur astronomer in Crimea, and initially designated “C/2019 Q4” because, well, it looked like a regular comet. It was only after repeated observations by Borisov, and confirmed by other amateur and professional astronomers, that the object’s path and speed through the solar system could be realized. It turned out to be traveling fast.

Like, really, really fast.

Clocked at a breakneck pace of 93,000 miles per hour (150,000 kilometers per hour), astronomers realized that C/2019 Q4 was a special kind of comet. While it was found to possess the characteristics of a regular comet (it has a faint coma and tail) there is no way that it’s gravitationally bound to our Sun. Its trajectory is hyperbolic. In other words, it didn’t originate in our solar system—it’s an alien visitor.

This simple animation depicts the comets path through our neighborhood; there’s little ambiguity in the fact that it doesn’t intend to hang around for very long:

With only a slight tug by our Sun’s gravity, the interstellar visit will careen out of the solar system in a few months. [NASA/JPL-Caltech]

Last week, these factors all culminated in the International Astronomical Union (IAU) officially classifying C/2019 Q4 as the second unambiguous interstellar comet discovery to date. It was therefore reclassified as “2I/Borisov” (1I/`Oumuamua being the first, of course). It’s thought interstellar junk passes through our solar system all the time, but only two comets (to date) have been confirmed to have an interstellar origin, suggesting our observational techniques are improving.

Now, the really neat thing about 2I/Borisov is that it’s a lot more active than `Oumuamua; the latter produced very little in the way of a discernible coma or tail after its discovery. Borisov, however, is being far more generous, already allowing astronomers to grab a crude spectroscopic snapshot of the gases being vented into space.

A Mysterious Interstellar Time Capsule

After being thwarted by the glare of the Sun on Sept. 13, an international team of astronomers was able to use the William Herschel Telescope on La Palma in the Canary Islands in the morning of Sept. 20 to measure the light that was being scattered off the gases in its tenuous coma. Follow-up spectral analysis by the TRAPPIST-North telescope in Morocco was also used.

Measuring the spectrum of Borisov allows us to understand the chemical composition of the ices that are fizzing into space as they are slightly heated by our Sun’s radiation via a process known as sublimation. And this is profoundly awesome.

To capture the spectra of any comet reveals the chemicals it contained when it formed billions of years ago. In our solar system, comets are considered to be icy time capsules; they formed from the solar nebula when the Sun was a proto-star and the planets were just starting to accrete from the surrounding protoplanetary disk of ancient debris. To see the chemicals contained within the vapor of these fizzing “dirty snowballs” gives us a five-billion-year-old glimpse of what the solar nebula and its system of baby planets would have contained.

2I/Borisov as imaged by the Gemini North Telescope on Hawaii. [GEMINI OBSERVATORY/NSF/AURA/INTERNATIONAL ASTRONOMICAL UNION]

Borisov wasn’t formed in our solar nebula, however, it was formed from the nebula of a distant, unknown star of unknown age. We have little idea as to where or when it originated (though there’s little doubt that astronomers will use data from the European Gaia space telescope to try to figure out a rough estimate, as they did with `Oumuamua).

Surprisingly Familiar

While previous observations of the comet’s nucleus have revealed a reddish tinge that is similar to the long-period comets that originate from our solar system’s Oort Cloud (such as Hale-Bopp and Hyakutake), the new study has been able to identify another familiar trait: its venting gases contain cyanogen. This chemical is a simple, yet toxic molecule containing one carbon atom and a nitrogen atom (CN). Cyanogen is commonly found in regular comets born in the solar system.

The researchers were also able to make an estimate of the ratio of the dust to gas that is being blasted from the comet’s nucleus and, you guessed it, it is roughly in agreement to what you’d expect a regular comet to generate.

All of these findings point to an unexpected conclusion, as the researchers highlight in their paper: “If it were not for its interstellar nature, our current data shows that 2I/Borisov would appear as a rather unremarkable comet in terms of activity and coma composition.” In other words, if it wasn’t for its extreme speed, 2I/Borisev would look like a regular comet from our solar system.

Does this mean all comets from any star system have similar compositions? That doesn’t seem possible, considering we know other stars and their associated nebulae their comets would have formed from contain different chemicals to our own. It could just mean that Comet Borisov was ejected from a nearby star that formed in the same stellar nursery as our Sun five billion years ago and should therefore contain approximately the same chemicals. But for now, it’s too early to say.

Obviously, more work needs to be done and, fortunately, we have time. The comet will reach perihelion (point of closest approach to the Sun) in early December, and astronomers are predicting maximum nucleus activity in December and January before it starts to recede into the interstellar night.

So, watch this space.

The Sun Is a Beautifully Blank Billiard Ball for Halloween

For the festive season, our nearest star is keeping its choice of costume simple.

I’m not saying the Sun isn’t being creative, it’s just not putting too much effort into this year’s stellar fancy dress party. I mean, look at it:

The Sun right now, as seen by the Helioseismic and Magnetic Imager (HMI) instrument on NASA’s Solar Dynamics Observatory (SDO) [NASA/SDO]

That flawless orange billiard ball is the photosphere of our Sun. Have you ever seen something so smooth and beautifully unremarkable?

Well, you have now, and its blank gaze is actually the reason why it’s causing a bit of a stir. According to our ever watchful solar sentry, Tony Phillips at SpaceWeather.com, the northern summer of 2019 may go down in history as “the summer without sunspots.”

From June 21st until Sept 22nd, the sun was blank more than 89% of the time. During the entire season only 6 tiny sunspots briefly appeared, often fading so quickly that readers would complain to Spaceweather.com, “you’ve labeled a sunspot that doesn’t exist!” (No, it just disappeared.) Not a single significant solar flare was detected during this period of extreme quiet.
Dr. Tony Phillips

So, what does this mean?

Sunspots are the visual cues for magnetic turmoil within our nearest star. Over cycles of approximately 11 years, the Sun’s internal magnetic field becomes stretched and twisted, driving the ebb and flow of space weather.

Starting with our solar billiard ball here, suffice to say that the solar magnetic field is pretty untwisted and, well, chilled. This is the epitome of “solar minimum” — and, as commented on by Phillips, a deep, potentially record-breaking solar minimum at that. It’s very likely that this is as minimum as solar minimum can be, so we could hazard a guess to say that things are going to start getting interesting very soon.

Differential rotation and the formation of coronal loops as demonstrated by my awesome abilities as a Microsoft Word artist [source: my PhD thesis!]

As our Sun is a massive blob of magnetized plasma, it doesn’t rotate uniformly (like the Earth does), it actually rotates a little faster at its equator than at its poles, a phenomenon known as “differential rotation.” Now, if you imagine the solar magnetic field as straight lines running from pole to pole, you can imagine that, over time, the field will start to wrap around the equator like an elastic band being stretched out of shape and wrapped around the middle. At its most extreme, so much rotational tension will be applied to the magnetic field that it becomes contorted. This contortion creates an upward pressure, forcing vast loops of magnetized plasma, known as coronal loops, to pop through the Sun’s photosphere — a.k.a. the solar “surface” — like annoyingly twisted loops of garden hosepipe (see the diagram above).

As its most extreme, in a few years time, we can expect our boring ol’ billiard ball to look something like this:

The Sun in 2014 (during the previous solar maximum), as seen by the SDO’s HMI [NASA/SDO]

About those blotches: those dark spots are sunspots and they are a direct consequence of the magnetic turmoil that rumbles inside the Sun during solar maximum. Remember those coronal loops I was talking about? Well, these huge, beautiful arcs of plasma cause the hotter outer layers of the Sun to be pushed aside, exposing the comparatively cooler (though still thousands of degrees) plasma under the surface — that’s what creates those dark blotches. And by counting sunspots, you can gauge how magnetically active the Sun is.

By viewing the Sun in different wavelengths, we can view the Sun’s atmosphere at different temperatures and, as the Sun’s atmosphere (the corona) is counter-intuitively hotter the higher above the surface you get, let’s take a look at what solar maximum looks like above these sunspots:

Yikes! The Sun’s corona in October 2014 (during the previous solar maximum), as seen by the SDO’s Atmospheric Imaging Assembly (AIA) instrument. And a damn fine effort just in time for Halloween. [NASA/SDO]

As you can see, there’s a lot of coronal loops erupting through the surface, creating huge regions of activity (called active regions, unsurprisingly). And the above observation was captured on Oct. 8, 2014, when the Sun was, apparently, in a terrifyingly festive Halloween mood! These regions can be hothouses for solar flares and coronal mass ejections; explosive phenomena that can have dramatic space weather effects on Earth.

So that was solar maximum; what does the solar corona look like now, at solar minimum?

*The Sun’s corona right now, as seen by the SDO’s AIA [NASA/SDO]*

Yep, as you guessed, very relaxed. In this state, we can expect very little in the way of explosive space weather events, such as flares and CMEs; there’s simply too little magnetic energy at solar minimum to create many surprises (caveat: even solar minimum can generate flares, they’re just few and far between).

While the Sun may look boring, the effects of space weather are anything but. During these times of solar minimum, the extended solar magnetic field (called the heliosphere), a magnetic bubble that reaches beyond the orbits of all the planets, contracts and weakens, allowing more cosmic rays from energetic events from the rest of the cosmos to reach Earth. Cosmic rays are ionizing particles that can boost the radiation exposure of astronauts and frequent fliers. Also, the solar wind can become a more persistent presence; streams of energized particles that are continuously streaming from the lower corona, so we still get our aurorae at high latitudes.

Recognition that the Sun is now in a deep minimum means the solar vacation is nearing an end. Astronomers have reported that of the handful of sunspots have made an appearance over the last few months with a flip in magnetic polarity, which can mean only one thing: Solar Cycle 25 is coming and the next solar maximum is only four years away.

Sadly, ‘Oumuamua Isn’t Piloted by Joyriding Aliens

An international team of experts have teamed up to conclude that the interstellar visitor isn’t what we hoped it was.

An artist’s impression of the strangely-elongated interstellar object ‘Oumuamua that zoomed through our solar system in 2017 [ESO/M. Kornmesser]

It probably comes as no surprise that the scientific consensus of ‘Oumuamua’s origins have concluded that it is a natural object, despite how funky and alien spaceship-looking the interstellar visitor at first appeared. According to a new study published today in the journal Nature Astronomy, the findings of 14 international experts have been pooled to categorically say that ‘Oumuamua isn’t an artificial object piloted by an intelligent extraterrestrial species, but instead “has a purely natural origin.”

“The alien spacecraft hypothesis is a fun idea, but our analysis suggests there is a whole host of natural phenomena that could explain it,” said the team’s leader Matthew Knight, from the University of Maryland, in a statement.

This most recent study comes hot on the heels of a fair amount of speculation that the spinning cigar-shaped object, which was detected by the Pan-STARRS1 telescope in Hawaii on Oct. 19, 2017, could be artificial. One of the more vocal advocates of this possibility, Avi Loeb of Harvard University, investigated the idea that ‘Oumuamua may be an interstellar probe that used our sun’s radiation pressure for a boost in velocity as it flew through the inner solar system. While the world’s media loved this concept (as did I), many scientists balked and emphasized the need to take the Occam’s razor approach and instead focus on natural explanations, not aliens. But, as pointed out by Loeb, while more likely explanations existed, considering the most extreme ones is still a part of the scientific process.

“This is how science works,” said Loeb in an interview for The Harvard Gazette late last year. “We make a conjecture … and if someone else advances another explanation, we will compare notes and the next time we see an object of this type we will hopefully be able to tell the difference. That’s the process by which science makes progress.”

Deep down, we all had the sense that the interstellar visitor likely wasn’t aliens (though it did spawn some wonderful debates about mind-boggling interstellar distances, the challenges of visiting other star systems, and why ET would bother popping by for a whistle-stop tour without saying “hi”), but this new study convincingly sounds the death knell for the possibility of aliens taking a joyride through our galactic neighborhood.

The new study is clear, in which the researchers write: “Here we review our knowledge and find that in all cases, the observations are consistent with a purely natural origin for ‘Oumuamua.”

So, what does the study conclude?

The object is most likely an ancient interstellar comet that randomly encountered our solar system after drifting through interstellar space for millions of years. The mechanisms by which ‘Oumuamua was ejected from its star system of birth remains up for debate, but the study’s authors point to the likelihood of a Jupiter-like world that may have gravitationally ejected the object when it strayed too close, helping it achieve escape velocity and a future lost deep in the interstellar expanse—until it encountered our solar system.

Even the behavior of the ancient comet as it traveled through the inner solar system agrees with theoretical predictions. The small boost in velocity as it made close approach to our sun was caused by ices (entombed under ‘Oumuamua’s surface) being heated and vented into space as a vapor (and not aliens hitting the gas). This behavior in comets is well-known, but the problem with ‘Oumuamua is that it exhibited few signs of being a comet—it didn’t develop a tail nor did it develop a coma, two clues of its cometary nature. But this object is different from the comets we know; it has been drifting through the galaxy for eons, perhaps it lost the majority of its ice in previous stellar encounters, or perhaps it contained little in the way of volatiles during its formation. Comets and asteroids also have a lot more in common that the textbooks may tell us, so perhaps it did vent small quantities of vapor to give it a boost, but not enough for astronomers to observe a tail and coma. In short, ‘Oumuamua shares similar traits to other objects that exist in our solar system

“While ‘Oumuamua’s interstellar origin makes it unique, many of its other properties are perfectly consistent with objects in our own solar system,” added Robert Jedicke of the University of Hawai’i’s Institute for Astronomy (IfA) and collaborator in the Nature Astronomy study.

The key thing that makes ‘Oumuamua so captivating, however, is not how it behaved when it entered the solar system and used the sun to change its course, it’s that we know it came from interstellar space, the first of its kind that we’ve ever encountered. Undoubtedly, the solar system has been visited countless times by junk that has been shed by other stars in our galaxy—there’s a lot of stars carrying around a lot of comets and asteroids, after all, they’re probably scattered around the Milky Way like baby’s toys being thrown out of strollers—but this is the first, special interstellar visitor that we’ve only just had the ability to detect.

The best news? There will be more.

Humanity is rapidly advancing through a “golden age” for astronomy and, if these interstellar vagabonds are as common as we now believe, we’re on the verge of detecting many more of them. For example, the Large Synoptic Survey Telescope (LSST), which is being constructed in Chile, is expected to become operational in 2022 and it will be so powerful that astronomers predict at least one ‘Oumuamua-like object will be spotted per year. Once we grasp how often these things turn up, perhaps we’ll be prepared enough to have a robotic spacecraft intercept one to see what these visitors from other stars really look like instead of depending on distant observations.

Of course, this whole episode could be a cautionary tale. Perhaps our advanced alien neighbors disguise their spacecraft to look like passing comets to get a closer look of primitive intelligences such as ourselves.* ‘Oumuamua being identified as an interstellar comet is exactly what they want us to believe…

*This was inspired by a tweet I read this morning, but I forgot who tweeted it and it appears I didn’t “like” it, so it’s since been lost to the twitterverse. Thank you to whomever tweeted it, it formed the seed to this blog!

Coolest White Dwarf Is a Glimpse of What Happens Long After Our Sun Dies

All good things come to a cold and dusty end.

[NASA’s Goddard Space Flight Center/Scott Wiessinger]

“So, what do you think happens after you die?”

The question was more of an accusation. The lady asking was sitting across from me at a Christmas dinner a friend of mine was hosting and the previous query was one about my religion. She wasn’t impressed by my response.

Granted, it probably wasn’t the ideal setting to say that I was an atheist, but I wasn’t going to lie either.

“Um, well…” I remember feeling vulnerable when I responded, especially as I’d only just met half the dozen people in the room, including the lady opposite, but I remember thinking: stick with what you know, Ian. So, I continued: “When I’m dead, all the elements from my body will remain on Earth,” — I didn’t want to go into much detail about my real plan of having my remains blended up into a jar and then launched into space (more on that in a future post, possibly) — “and those elements will get cycled through the biosphere through various biological, chemical and physical processes for billions of years. Eventually, however, all good things must come to an end and the sun will run out of fuel, ballooning into a huge red giant star, leaving what is known as a white dwarf in its wake.” (By her glazed look, I could tell she regretted asking, but I continued.) “If, and it’s a big IF, the Earth survives this phase of stellar death, our planet might be hurled out of the solar system. Or, and this is my favorite scenario,” — I’d hit my stride and everyone else seemed to be entertained — “it might careen inward, toward the now tiny white dwarf sun, where Earth will be ripped to sheds under powerful tidal forces, sending all the rocks, dust, and the elements that used to be my body, raining down onto the white dwarf.”

This is an abridged version. I also went into some white dwarf science, why planetary nebulae are cool, and how our sun as a white dwarf would stand as a monument to the once great solar system that will be gone five billion years from now. The recycled elements from my long-gone body could eventually rain down onto the atmosphere of a newborn white dwarf star — pretty cool if you ask me. This might be more of a cautionary tail about inviting an atheist astrophysicist to religious celebrations, but I feel my tabletop TED talk was good value for money. And besides, by turning that inevitable “what religion are you?” question into a scientific one, I hadn’t gotten bogged down with justifying why I’m an atheist — a conversation that, in my experience, never works out well over dinner.

So, why am I remembering that fun evening many years ago? Well, today, there’s some cool white dwarf news. And I love white dwarf news, especially if it’s about dusty white dwarfs. Because dusty white dwarfs are a reminder that nothing lasts forever, not even our beautiful 5-billion-year-old solar system.

One Cool Dwarf

A citizen scientist working on the NASA-led “Backyard Worlds: Planet 9” project has discovered the coldest and oldest white dwarf ever found. The project’s aim is to seek out as-yet-to-be-discovered worlds beyond the orbit of Neptune (re: “Planet Nine” and beyond). Through the analysis of infrared data collected by NASA’s Wide-field Infrared Survey Explorer, or WISE (inspired by data from the European Gaia mission), Melina Thévenot was looking for local brown dwarfs — failed stars that lack the mass to sustain nuclear fusion in their cores, but pump out enough infrared radiation to be detected. In the observations, Thévenot spied what she thought was bad data, but with the help of WISE, she found not a nearby brown dwarf, but a white dwarf that was brighter and further away. After sharing her discovery with the Backyard Worlds team, astronomers at the W. M. Keck Observatory confirmed that not only was that white dwarf lowest temperature specimen yet found, it was also very dusty. In fact, it’s thought that the white dwarf, designated LSPM J0207+3331, has multiple dusty rings. Its discovery, however, is something of a conundrum and the researchers think it may challenge planetary models.

“This white dwarf is so old that whatever process is feeding material into its rings must operate on billion-year timescales,” said astronomer John Debes, at the Space Telescope Science Institute in Baltimore, in a NASA statement. “Most of the models scientists have created to explain rings around white dwarfs only work well up to around 100 million years, so this star is really challenging our assumptions of how planetary systems evolve.”

Interesting side note: It was Debes who first got me excited about dusty white dwarfs when I met him at the 2009 American Astronomical Society (AAS) meeting in Long Beach, Calif. You can read my enthusiastic Universe Today article I wrote on the topic here.

After deducing the tiny Earth-sized star’s cool temperature — 10,500 degrees Fahrenheit (5,800 degrees Celsius) — the researchers estimate that the white dwarf is approximately 3-billion years old. The infrared signal suggests a copious quantity of dust is present, which is a bit weird. As I alluded to in my tabletop TED talk, after a sun-like star runs out of fuel and puffs up into a red giant, it will leave a shiny white dwarf surrounded by a planetary nebula in its wake. Should any mangled planet, asteroid or comet that survived the red giant phase stray too close to that white dwarf, it’ll get shredded. So, it’s poignant when astronomers find dusty white dwarfs; it means those star systems used to have some kind of planetary system, but the white dwarf is in the process of destroying it. That is the inevitable demise of our solar system in 5 billion years time. But to find a 3-billion-year-old specimen with a ring system doesn’t make a whole lot of sense — the white dwarf had plenty of time to consume all that dusty debris by now, a process, according to Debes, that should only take 100 million years to complete.

Debes, who led the study published in The Astrophysical Journal on Feb. 19, and his team, including discoverer and co-author Thévenot, has some idea as to what might be going on, but more research is needed. One hypothesis is that J0207’s dusty ring is composed of multiple rings with two distinct components, one thin ring just at the edge of where the star is breaking up a belt of asteroids and a wider ring closer to the white dwarf. It’s hoped that follow-up observations by the next generation of space telescopes, such as NASA’s James Webb Space Telescope (JWST), will be able to deduce what those rings are made of, thus helping astronomers understand the evolution of these ancient star systems.

Besides being the ultimate way to gain perspective on our tiny existence (and an excellent topic for an awkward dinner conversation), this research underpins a powerful way in which citizen scientists are shaping space science, particularly projects that require many human brains to process vast datasets.

“That is a really motivating aspect of the search,” said Thévenot, who is one of more than 150,000 volunteers who works on Backyard Worlds. “The researchers will move their telescopes to look at worlds you have discovered. What I especially enjoy, though, is the interaction with the awesome research team. Everyone is very kind, and they are always trying to make the best out of our discoveries.”

Faint Fossil Found in Solar System’s Suburbs

A tiny rock has been detected in the Kuiper belt, which may not seem like such a big deal, but how it was found is.

We think we have a pretty good handle on how planets form. After the birth of a star, big enough clumps of dust and rock in the disk of leftover debris begin to accrete mass until they turn into spheres under the pull of their own gravity, jostling around, pushing smaller protoplanets out of the way and being shoved aside by, or smashing, into larger ones. Whatever planets survive this messy process end up becoming a solar system. We’ve seen this around other stars and aside from a few interesting twists on this model, we think we know what’s going on pretty well by now.

But there was one piece missing. The math says that to start the planet building process, you need a kind of planetary seed between one and ten kilometers wide. Since we happen to live in a solar system, we should be able to look outwards, towards the Kuiper Belt, which we think is made primarily from the leftovers of planetary formation, and see these protoplanetary fossils drifting across the sky. However, the process has proven to be rather tricky. These rocks are very faint and rather small compared to everything else we can usually see, so looking for them is kind of like trying to spot a grain of dust in a room illuminated only by moonlight, which is why we have so much trouble finding them.

Or at least we did until now, when a 1.3 kilometer Kuiper Belt Object, or KBO was spotted by a simple setup and commercially available cameras as it eclipsed background stars. While that might not sound like much right now, it’s actually an extremely important finding. First, it tells us how to find tiny KBOs so we can take a proper survey of protoplanetary leftovers. Secondly, it shows that we’re correct in our solar system formation model and demonstrated that predicted artifacts of baby planets that never quite made it do exist. The next part will be to try and detect more of these little planet seedlings to figure out how efficient the formation process is, and see what we can learn from that.

As noted, these finds don’t just apply to our own solar system, but to pretty much every planet in the universe. Just consider that mighty gas giants with swirling storms that could swallow Earth whole, exotic icy dwarfs with percolating cryovolcanoes and towering peaks dusted with reddish organic molecules, and tropical worlds with deep oceans teeming with life — which might even be home to an alien civilization living through its heyday — all started out as these little rocks lucky enough to clump together for a few hundred million years, find a stable orbit, and cool down enough to become a cosmic petri dish. They might not be impressive or exciting on their own, but that doesn’t mean they aren’t profoundly important.

Reference: Arimatsu, K., et. al., (2019) A kilometre-sized Kuiper belt object discovered by stellar occultation using amateur telescopes, Nature Astronomy Letters, DOI: 10.1038/s41550-018-0685-8

[This article originally appeared on World of Weird Things]

Oldest Earth Rock Found In Lunar Exile

When our young planet was taking a beating by massive impacts, bits were ejected into space—and some ended up on the moon.

An artist’s impression of what our planet probably looked like over 4 billion years ago, during the violent Hadean epoch [Simone Marchi (SwRI), SSERVI, NASA]

This is an interesting thought: When Apollo astronauts were busy exploring the lunar surface, it wasn’t just moon rocks that were crunching beneath their moon boots—bits of Earth were there too. But how did Earth stuff get mixed-in with moon stuff?

According to a new study published in the journal Earth and Planetary Science Letters, this question may be a controversial one, but it’s not without some compelling evidence.

During the Apollo 14 moon landing in February 1971, when NASA astronauts Alan Shepard and Ed Mitchell were exploring the Fra Mauro Highlands, they scooped up some moon rocks and returned them to Earth for study. Fast-forward 48 years and an international group of researchers think that a 2 gram shard of rock in one of their scoops has terrestrial origins. That is a cool find in itself, but this particular sample is ancient, and possibly the oldest sample of Earth rock ever found, heralding from a time when the Earth was a very different place.

Between 4 and 4.6 billion years ago, our planet was a mess. Still in the process of forming, it was getting pummeled by an incessant barrage of asteroids and comets. Many parts of the Earth’s surface would have been molten, all of it would have been cratered, and none of the continents or oceans that we are familiar with today would have been present (see the image at the top of this page for an imagining of what it may have looked like). This was the Hadean epoch — named after the Greek god of the underworld, Hades — and it would have been a hellish time.

Apollo 14’s Ed Mitchell using a map during an EVA [NASA]

With all these impacts, large and small, it seems logical to think that a few of these impacts would have been large enough to launch a sizable quantity of debris into space. Back then, the moon orbited Earth much closer than it does now — four times closer in fact (which is a cool thought; the moon would have loomed four times larger in Hadean skies than it does now). As the moon was closer, there would have been higher odds of the terrestrial collision debris to come crashing down on the lunar surface. And this was the beginning of the epic journey of the 2 gram shard of rock that was returned to Earth and now lives in a lab.

The international team of researchers are associated with the Center for Lunar Science and Exploration, a part of NASA’s Solar System Exploration Research Virtual Institute, and they carried out a new analysis technique to search for Earth rocks in the Apollo moon samples. In one of the samples was a piece that is composed of quartz, feldspar, and zircon. These minerals are all common on Earth, but not on the lunar surface. Their interest was piqued. Further chemical analysis of the sample revealed how the rock formed: it crystallized in an oxidized atmosphere at temperatures more akin to Earth’s at the time. Moon rock typically crystallized at much higher temperatures devoid of an oxygen-rich atmosphere. The implication is clear: this particular sample didn’t form on the moon, it formed on Hadean Earth. But its journey from the Earth to the moon and into an Apollo astronaut’s sample scoop is quite the epic story.

A sample of moon rock collected by Apollo 14 astronauts [NASA]

Through the chemical analysis on the sample, a surprising amount of detail about the hows and whens could be deduced. First, after considering the mineral components of the sample, the rock must have formed around 20 kilometers under the surface, in young Earth’s crust, approximately 4.1 billion years ago. At the time, it wasn’t uncommon for massive impacts to excavate craters thousands of kilometers wide. These impact events would have easily have reached 20 kilometers deep, blasting some Earth stuff into space. The 2-gram sample was likely part of a bigger chunk that eventually collided with the moon, creating its own lunar crater, where it remained, in relative peace for a couple of hundred million years. Then, around 3.9 billion years ago, another lunar impact pummeled the sample, partially melting it, burying it deeper under the moon’s surface.

This sample holds this incredible record of geological history of a time when massive impacts were very common, when planets were accreting mass and life was just beginning to emerge on an embryonic Earth. After that lunar impact, the sample remained buried in moon rock for a few billion years.

Then, 26 million years ago, a comparatively small meteoroid slammed into the moon to create the 340-meter wide Cone Crater. The 2-gram sample was once again kicked onto the moon’s surface where it was randomly scooped by Shepard or Mitchell in 1971. The photograph below shows the boulders at the rim of Cone Crater where the sample was collected:

A photo taken on the Apollo 14 mission in the Fra Mauro highlands of the moon showing a cluster of boulders on the rim of Cone Crater during EVA-2 [NASA]

Although it may be logical to assume that ancient rocky debris from Earth likely ended up on the moon’s surface, it’s phenomenal that a tiny piece of Hadean Earth was discovered in an Apollo 14 sample. This could be an indicator as to how common it is; Earth rock preserved for billions of years on a world with no weather or tectonic processes continually erasing signs of the geological past, helping us better understand how our planet evolved.

Psychedelic Simulation Showcases the Ferocious Power of a Solar Flare

Scientists are closing in on a better understanding about how these magnetic eruptions evolve

[Mark Cheung, Lockheed Martin, and Matthias Rempel, NCAR]

For the first time, scientists have created a computer model that can simulate the evolution of a solar flare, from thousands of miles below the photosphere to the eruption itself in the lower corona — the sun’s multimillion degree atmosphere. And the results are not only scientifically impressive, the visualization is gorgeous.

I’ve always had a fascination with the sun — from how our nearest star generates its energy via fusion reactions in its core, to how the tumultuous streams of energetic plasma slams into our planet’s magnetosphere, igniting spectacular aurorae. Much of my interest, however, has focused on the lower corona; a region where the intense magnetic field emerges from the solar interior and reaches into space. With these magnetic fields comes a huge release of hot plasma that is channeled by the magnetism to form beautiful coronal loops. Intense regions of magnetism can accumulate in violently-churning “active regions,” creating sunspots and explosive events — triggered by large-scale magnetic reconnection — such as flares and coronal mass ejections (or CMEs). This is truly a mysterious place and solar physicists have tried to understand its underlying dynamics for decades.

The eruption of an X-class solar flare in the sun’s multimillion degree corona [NASA/SDO]

Now, with increasingly-sophisticated solar observatories (such as NASA’s Solar Dynamics Observatory), we are getting an ever more detailed look at what’s going on inside the sun’s deep atmosphere and, with improvements of theoretical models and increases in computer processing power, simulations of the corona are looking more and more like the real thing. And this simulation, detailed in the journal Nature Astronomy, is truly astonishing.

In the research, led by researchers at the National Center for Atmospheric Research (NCAR) and the Lockheed Martin Solar and Astrophysics Laboratory, the evolution of a solar flare has been modeled. This simulation goes beyond previous efforts as it is more realistic and creates a more complete picture of the range of emissions that can be generated when a solar flare is unleashed.

One of the biggest questions hanging over solar (and indeed, stellar) physics is how the sun (and other stars) heat the corona. As we all know, the sun is very hot but its corona is too hot; the photosphere is a few thousand degrees, whereas, only just above it, the coronal plasma skyrockets to millions of degrees, generating powerful radiation beyond what the human eye can see, such as extreme-ultraviolet and X-rays. Basic thermodynamics says that this shouldn’t be possible — this situation is analogous to finding the air surrounding a light bulb is hotter than the bulb’s glass. But what our sun has that a light bulb does not is a powerful magnetic field that dictates the size, shape, temperature and dynamics of the plasma our sun is blasting into space. (If you want some light reading on the subject, you can read my PhD thesis on the topic.)

“This work allows us to provide an explanation for why flares look like the way they do, not just at a single wavelength, but in visible wavelengths, in ultraviolet and extreme ultraviolet wavelengths, and in X-rays. We are explaining the many colors of solar flares.”
Mark Cheung, staff physicist at Lockheed Martin Solar and Astrophysics Laboratory.

The basis of this new simulation, however, investigates another mystery: How and why do solar flares erupt and evolve? It looks like the research team might be on the right track.

When high-energy particles from the sun impact our atmosphere, vast light shows called auroras can be generated during the geomagnetic storm, as shown in this view from the International Space Station [NASA]

Inspired by a powerful flare that was observed in the corona in March 2014, the researchers provided their magnetohydrodynamic model with an approximation of the conditions that were observed at the time. The magnetic conditions surrounding the active region were primed to generate a powerful X-class flare (the most powerful type of solar flare) and several less powerful (but no less significant) M-class flares. So, rather than forcing their simulation to generate flares, they re-enacted the conditions of the sun that were observed and just let their simulation run to create its own flares.

“Our model was able to capture the entire process, from the buildup of energy to emergence at the surface to rising into the corona, energizing the corona, and then getting to the point when the energy is released in a solar flare,” said NCAR scientist Matthias Rempel in a statement. “This was a stand-alone simulation that was inspired by observed data.

“The next step is to directly input observed data into the model and let it drive what’s happening. It’s an important way to validate the model, and the model can also help us better understand what it is we’re observing on the sun.”

Solar flares, CMEs and even the solar wind can have huge impacts on our technological society. The X-rays blasting from the sun’s atmosphere millions of miles away can have dramatic impacts on the Earth’s ionosphere (impacting communications) and can irradiate unprotected astronauts in space, for example. CMEs can be launched from the corona and arrive at Earth orbit in a matter of hours or days, triggering geomagnetic storms that can impact entire power grids. We’re not just talking a few glitches on your cellphone here; satellites can be knocked out, power supplies neutralized and global communications networks interrupted. It’s simulations like these, which aim to get to the bottom of how these solar storms are initiated, that can help us better prepare for our sun’s next big temper tantrum.

For more on this research, watch this video:

Life Beneath Europa’s Ice Might Be a Non-Starter

New models trying to infer the geology of potentially habitable moons orbiting Jupiter and Saturn hint at surprisingly cool, geologically inactive worlds, the opposite of what a diverse alien ecosystem would need

Imagine a spaceship finally landing on Europa and slowly drilling into the ice. After weeks of very careful progress, it pierces the moon’s frozen shell and releases a small semi-autonomous submarine connected to the probe with an umbilical to ensure constant communication and a human taking over in case of an emergency. Much of the time, it will chart a course of its own since piloting it with an hour long delay between command and response would be less than ideal. It navigates through the salty ocean, shining its light on structures never before seen by a human eye, making its way deeper and further into the alien environment to find absolutely… nothing at all.

That’s the sad scenario proposed by a team of geologists who crunched the numbers on the four leading contenders to host alien life in our outer solar system: Europa, Ganymede, Titan, and Enceladus. According to their models, looking at gravity, the weight of water and ice on the rocks underneath, and the hardness of the rocks themselves, these moons would be more or less geologically dead. Without volcanoes or sulfur vents, there would be very little in terms of nutrient exchange and therefore, very little food and fuel for an alien ecosystem more complex than microbe colonies.

Of course, these results are a pretty serious departure from the hypotheses commonly held by planetary scientists that the gravity of gas giants cause tidal kneading inside their moons, citing Io as an example. According to the researchers’ model, only Enceladus would be a promising world to look for life, as evidenced by the plumes breaking through its icy crust, spraying organic material into space. The reason why the numbers are different, they say, is because its core is likely to be porous, meaning its ocean would be heated deep inside the moon, fueling geysers and churning organic matter while effectively making the little world a ball of soggy slush.

Since these findings are so different from what’s implied by observations, the researchers aren’t in a rush to publish them are are soliciting other scientists’ opinions to make sure they have a complete picture, and lead investigator Paul Byrne grumbled about his disappointment with what the models indicate. That said, while he’s hoping to be proven wrong, we shouldn’t forget that these are alien worlds and while we’ve spent decades studying them, our knowledge came in bursts. Simply put, we might know a fair bit but far from everything and disappointing surprises may lurk under their icy surfaces and subterranean oceans.

[This article originally appeared on World of Weird Things]

This Weird Star System Is Flipping Awesome

The binary system observed by ALMA isn’t wonky, it’s the first example of a polar protoplanetary disk

Artwork of the system HD 98000. This is a binary star comprising two sun-like components, surrounded by a thick disk of material. What’s different about this system is that the plane of the stars’ orbits is inclined at almost 90 degrees to the plane of the disk. Here is a view from the surface of an imagined planet orbiting in the inner edge of the disk [University of Warwick/Mark Garlick].

Some star systems simply don’t like conforming to cosmic norms. Take HD 98000, for example: It’s a binary system consisting of two sun-like stars and it also sports a beautiful protoplanetary disk of gas and dust. So far, so good; sounds pretty “normal” to me. But that’s only part of the story.

When a star is born, it will form a disk of dust and gas — basically the leftovers of the molecular cloud the star itself formed in — creating an environment in which planets can accrete and evolve. Around a single star (like our solar system) the protoplanetary disk is fairly well behaved and will create a relatively flat disk around the star’s spin axis. For the solar system, this flat disk would have formed close to the plane of the ecliptic, an imaginary flat surface that projects out from the sun’s equator where all the planets, more or less, occupy. There are “wonky” exceptions to this rule (as, let’s face it, cosmic rules are there to be broken), but the textbook descriptions of a star system in its infancy will usually include a single star and a flat, boring disk of swirling material primed to build planets.

Cue HD 98000, a star system that has flipped this textbook description on its head, literally. As a binary, this is very different to what we’re used to with our single, lonely star. Binary stars are very common throughout the galaxy, but HD 98000 has a little something extra that made astronomers take special note. As observed by the Atacama Large Millimeter/sub-millimeter Array (ALMA), its protoplanetary disk doesn’t occupy the same plane as the binary orbit; it’s been flipped by 90 degrees over the orbital plane of the binary pair. Although such systems have been long believed to be theoretically possible, this is the first example that has been found.

“Discs rich in gas and dust are seen around nearly all young stars, and we know that at least a third of the ones orbiting single stars form planets,” said Grant M. Kennedy, of the University of Warwick and lead author of the study published today in the journal Nature Astronomy, in a statement. “Some of these planets end up being misaligned with the spin of the star, so we’ve been wondering whether a similar thing might be possible for circumbinary planets. A quirk of the dynamics means that a so-called polar misalignment should be possible, but until now we had no evidence of misaligned discs in which these planets might form.”

Artwork of the system HD 98000. This is a binary star comprising two sun-like components, surrounded by a thick disc of material [University of Warwick/Mark Garlick]

This star system makes for some rather interesting visuals, as shown in the artist’s impression at the top of the page. Should there be a planetary body orbiting the stars on the inner edge of the disk, an observer would be met with a dramatic pillar of gas and dust towering into space with the two stars either side of it in the distance. As they orbit one another, the planetary observer would see them switch positions to either side of the pillar. It goes without saying that any planet orbiting two stars would have very different seasons than Earth. It will even have two different shadows cast across the surface.

“We used to think other solar systems would form just like ours, with the planets all orbiting in the same direction around a single sun,” added co-author Daniel Price of Monash University. “But with the new images we see a swirling disc of gas and dust orbiting around two stars. It was quite surprising to also find that that disc orbits at right angles to the orbit of the two stars.”

Interestingly, the researchers note that there are another two stars orbiting beyond the disk, meaning that our hypothetical observer would have four suns of different brightnesses in the sky.

The most exciting thing to come out of this study, however, is that ALMA has detected signatures that hint at dust growth in the disk, meaning that material is in the process of clumping together. Planetary formation theories suggest that accreting dust will go on to form small asteroids and planetoids, creating a fertile enviornment in which planets can evolve.

“We take this to mean planet formation can at least get started in these polar circumbinary discs,” said Kennedy. “If the rest of the planet formation process can happen, there might be a whole population of misaligned circumbinary planets that we have yet to discover, and things like weird seasonal variations to consider.”

What was that I was saying about “cosmic norms”? When it comes to star system formation, there doesn’t appear to be any.

Reference: https://warwick.ac.uk/newsandevents/pressreleases/double_star_system
Paper: https://www.nature.com/articles/s41550-018-0667-x