On February 14th, 2018 we learned about

TRAPPIST-1 planets orbits suggest they’re soaked in substantial amounts of water

In 2016, astronomers located a batch of presumably rocky exoplanets orbiting TRAPPIST-1, a red dwarf star 40 light years from Earth. While red dwarf stars are generally cooler than our own Sun, some of these planets have tight enough orbits to put them in habitable temperature ranges for life, assuming that life was happy living under a dim red sky. Continuing observations of the TRAPPIST-1 system has revealed more details about these worlds, including the likelihood of vast amounts of liquid water on their rocky surfaces.

Calculating exoplanet composition

At 40 light years away, astronomers aren’t observing signs of water or ice directly. Instead, they’re taking measurements of planets TRAPPIST-1b through TRAPPIST-1h and comparing how they interact with each other’s orbits. Like all matter, each planet creates its own gravitational field that pulls on its neighbors. While they’re not overpowering the pull of their star, researchers have been able to detect small wobbles in the tight orbits of each planet when they move near each other, allowing them to come up with estimates for how massive each planet might be. That information is then compared to estimates for the planets’ volumes, a figure based on how much light each planet blocks when passing in front of the TRAPPIST-1 star. To verify these estimates, researchers then plugged them into simulations of the system, making adjustments until their virtual orbits matched observed data.

Once each planet’s mass and volume were known, researchers calculated their density. The resulting picture of each planet’s composition isn’t inert pieces of rock, but worlds with large amounts of “volatile,” or more dynamic, materials on their surface. Based on the planets’ close proximity to their star, there’s a good chance that this volatile material is some form of water thanks to that molecule’s abundance in the materials that eventually go on to form planets. What’s more, there’s a good possibly that this water exists as a liquid under a thick, steamy atmosphere. Before you picture a second Earth under a reddish sky, planets like TRAPPIST-1b and TRAPPIST-1c may actually make our own planet look dry, as they’ve been estimated to be made of up to five percent water, versus Earth’s 0.02 percent.

Home to water, but without being wet

Not every TRAPPIST-1 planet is expected to be wet, spherical sauna though. TRAPPIST-1d is the smallest of the group, and may have a layer of ice on its surface. TRAPPIST-1e is a little denser than Earth, probably thanks to a more substantial iron core. It likely lacks a considerable atmosphere, with rockier composition overall. Further out, TRAPPIST-1f, g and h are probably too far from their star to maintain a large amount of liquid water, much less vapor. Any water they have would be frozen, and there’s no sign of a substantial atmosphere at this point.

Is there water around every red dwarf?

While there’s more to be learned about the TRAPPIST-1 system, researchers would also like to start using these simulations and analytical techniques on other red dwarf solar systems. It seems that not every star needs to be yellow-hot to be home to some very attractive-looking planets, but it would be great to know just how common these sorts of water-soaked spheres really are.

Source: TRAPPIST-1 planets probably rich in water by ESO, Science Daily

On January 16th, 2018 we learned about

Future spacecraft will likely navigate by the light of distant pulsars

The universe is expanding, and accelerating, every day. More locally, the planets in our solar system are whipping around the Sun at up to 107,082 miles-per-hour. All this can make it hard for a spacecraft to pick a reference point, which is part of why our current probes have to call home for directions so often. While we obviously want to communicate with our spacecraft as they explore the galaxy, finding a way for them to plot their own course a bit more would save time and energy. Fortunately, experiments with distant pulsars have been suggesting that they can be used as reliable sign-posts as we push further and further into space.

A pulsar is a special type of neutron star. They’re incredibly dense collections of debris made of the remnants of an exploded star with the added twist of also being highly magnetized. This magnetic polarization means that a pulsar emits x-ray energy from its north or south pole, rather than in all directions at once. Since the closest pulsar is around 280 light years away, we only see the emitted energy from a pulsar when it’s pointed in our direction, which happens on a regular schedule thanks to the pulsar’s rotation. In some cases those rotations are so fast that we get what appears to be a pulse of energy on a millisecond timescale, turning the pulsar into a handy blinking landmark that our spacecraft can use as a relatively stable reference point.

Piloting by pulsar

Right now, no probe is navigating by pulsar, but several instruments have been collecting data on them. The United States Navy has concluded a test with a satellite navigating by pulsar, and instruments on the International Space Station like the Neutron Star Interior Composition Explorer (NICER) have been collecting data both on the size of pulsars and how quickly they appear to “blink” from the perspective of our solar system. With these data, researches have come up with formulas that allow for a location in space to be identified within three miles.

As we refine our pulsar tracking abilities, researchers hope to reduce that margin of error to a half-mile. Once we can reliably triangulate an object’s location in relation to the energy from distant pulsars, spacecraft should be able to handle more navigation commands without calling back to Earth for updates. Pulsar-based navigation could also be used as a secondary navigation system for more sensitive missions, such as when humans attempt our first trip to Mars. The fact that tracking pulsars only requires a modestly-sized sensor makes this method of navigation quite practical, even if it requires enormous amounts of energy being blasted from from collapsed stars light years away to work.

Source: NASA test proves pulsars can function as a celestial GPS by Alexandra Witze, Nature

On January 10th, 2018 we learned about

Two meteorites found carrying liquid water and other ingredients needed for life

Delivery services are so convenient. You can get monthly boxes of toys and coffee, or even kits with ingredients for a dinner sent straight to your house. If you’re tolerant of unpredictable delivery schedule, you might even find organic compounds and liquid water, ready to be assembled into life as we know it. It’s not exactly farm-to-home, but scientists studying two particular arrivals are realizing that Ceres-to-Earth may be the next best thing.

The big catch with these deliveries is that they arrive via meteorites, and thus aren’t on the most predictable schedule. While asteroids of various sizes intersect with the Earth all the time, these particular space rocks survived a trip to the planet’s surface in 1998. One was found in Texas near a basketball court, while the other came months later in Morocco. The timing, similarity of composition and structural details suggest that these particular rocks came from two different points of origin, but may have been diverted to Earth thanks to a single collision in space. Scientists’ best guess is that the rocks were pieces of the dwarf planet Ceres and the asteroid Hebe, or at least pieces of those bodies’ descendants.

Petite portions

While the rocks themselves may have had a rough ride, the organic compounds and water molecules were safely stowed inside salt crystals the whole time. The water molecules in particular may even be 4.5 billion years old, dating back to the first days of our solar system. While the water, nitrogen carbon and other ingredients of hydrocarbons and amino acids were well-preserved, they arrived in quantities too small for even an appetizer. The crystals themselves were no bigger than 2 millimeters, and identifying these crucial compounds required the use of powerful tools like a scanning transmission x-ray microscopes (STXM).

Nonetheless, these tiny samples have bigger implications. They don’t suggest directly suggest that life exists on a place like Ceres, but they add to the growing evidence that life-friendly environments may be, or at least have been, more common than once thought. What’s more, those sources of organic compounds may be making regular deliveries around the solar system, seeding planets and other asteroids with all the ingredients needed to whip up some protein-producing goodness.

Source: Ingredients for life revealed in meteorites that fell to Earth by Lawrence Berkeley National Laboratory, Phys.org

On December 14th, 2017 we learned about

Despite our original estimates, Saturn’s iconic rings are a relatively recent addition to the solar system

As cool as Saturn’s hexagonal poles, massive wind storms and tantalizing moons may be, the planet is clearly defined by its rings. Even though it’s not the only planet to have rings around it in our solar system alone, the orbiting ice and rock are so pronounced that it’s hard to imagine the planet without them. In fact, for a long time the leading hypothesis was that Saturn had always had its rings, as they were thought to be formed from the same cosmic debris that formed the rest of the solar system. However, the evidence is stacking up against that idea, and it now seems that the sixth planet’s most famous feature is actually one of its more recent additions.

Not measuring enough mass

The first doubts about the rings’ age started in the 1980s, when the Voyager spacecraft took some quick measurements of Saturn as it flew towards the edge of the solar system. The data from Voyager suggested that the rings didn’t have nearly the mass they were expected to, especially if they had somehow been formed alongside the gas giant 4.6 billion years ago. These data weren’t considered conclusive, but fortunately Cassini arrived at Saturn in 2004 to offer a second opinion.

Cassini obviously gathered a lot of information about Saturn in its 13 years orbiting the planet, but the data most relevant to this study were gathered during the mission’s Grand Finale. Once the spacecraft had been fated for a fiery decommission in Saturn’s atmosphere, it wasn’t considered to be a huge risk to fly it through the space between the rings and the planet. The ring of most interest was the B ring, which was expected to have the mass of a small moon like Mimas. Instead, readings of the gravitational pull from the B ring were weaker than the ancient-rings model predicted, with the rings being just 40 percent of what they should be, supporting Voyager’s earlier measurements.

Missing billions of years of build-up

The size of Saturn’s B ring isn’t the only reference point in this study— there’s also plenty of dirt on other rings as well. Literally, the icy, reflective rings have been getting progressively dirtier over the ages thanks to a continual bombardment of sooty comets from the outer edges of the solar system. By measuring the rate of contamination, researchers have determined that they don’t have 4.6-billion-years of grime built up on them. They’re basically too clean to be that old, meaning the rings of Saturn have only been around for a few hundred million years, which isn’t long on a cosmic scale.

Why form when they did?

This presents a new challenge for researchers. While some had championed the idea of ancient rings, the evidence for much younger rings is convincing. The issue is coming up with a new model that can explain why they turned up when they did. Did something large hit Saturn, kicking debris into its orbit? Did one of the planet’s many moons get shattered? With rings this new, is there a chance that they’re not as stable as we’d assumed, leaving them primed to eventually collapse back to Saturn’s surface? Even with new information on the rings’ age, there are a lot of questions that need to be examined, and researchers feel like they’re basically at square one for an explanation. Sounds like a good excuse to send another robot.

Source: Saturn’s rings are a recent addition to the solar system, Cassini observations show by Paul Voosen, Science

On December 6th, 2017 we learned about

Newly discovered black hole is bafflingly large for being 13 billion years old

When you look at stars in the night sky, you’re not only seeing light from another place, but another time. Space is so vast that even light, moving at the fastest speed we can imagine, takes ages to reach our planet from other parts of the universe. So if you look at our solar system’s closest neighbor, Alpha Centauri, you’re seeing the light emitted by that star over four years ago. Bigger distances thus yield bigger gaps in time, which is how astronomers recently found evidence of a black hole from 13 billion years ago, long before the Earth, or most other planets, even existed.

Finding darkness in ultrabright objects

The light that was detected by wasn’t coming directly from the black hole itself, as those intensely massive objects don’t emit or reflect any light to see (hence their name). Any object that gets too close gets pulled into the black hole, but all that gravity is good for collecting a looser assortment of material in the immediate space around the black hole as well. In the case of this ancient black hole spotted by astronomers, they knew it was there it was surrounded by an ultrabright quasar, a cloud of energy-emitting particles orbiting the black hole at close to the speed of light.

By analyzing the light coming from quasar J1342+0928, the following profile of the black hole was put together. The supermassive black hole was around 800 million times the mass of our Sun, which isn’t surprising since it would have to be large to support a quasar around it. However, when combining that size plus its age, scientists started scratching their heads. How did such huge collection of mass exist only 690 million years after the Big Bang created our universe?

What existed in the early days of the universe?

As far as everyone could understand, there shouldn’t have been that much material in one place to form a giant black hole that early in our universe’s history. The current model is that after the Big Bang occurred, matter was first very energetic, but then calmed down into mostly neutral hydrogen atoms. Each proton and electron pair was balanced, and had no need to interact with its neighbors, meaning no energy was being released anywhere. This time in the universe’s history is known as the Cosmic Dark Ages, because no stars yet existed to emit any light. Everything was essentially inert.

Eventually, gravity started stirring things up. Particles began to clump and collide, forming larger atoms and reactions. New elements were created for the first time, as did collections of mass with enough nuclear activity to start emitting energy, becoming the first stars. As it happens, the light from the newly discovered quasar J1342+0928 was emitted at this time, meaning it existed when the entire concept of “stars” was just getting started.

Too old to be so big?

Which brings us back to how weird this timing is. The nuances of the light from quasar J1342+0928 help narrow down the date of the so-called Cosmic Dawn, but also raises new questions about what the state of the universe was at that time. If stars were still forming for the first time, how was enough matter somehow rounded up already to form a black hole 800 times bigger than our Sun? Smaller black holes are normally created from the collapse of a star, not congealing dust. This doesn’t necessarily contradict the model for the universe’s maturation, but instead has astronomers looking for new ways for black holes to form.


My four-year-old asked: What would happen to a person sucked into a black hole? To a car? To a house? To a… (etc.)

In almost every case, once that object got close enough to the black hole, crossing the so-called event horizon, it would be ripped and stretched to the center of the gravity-producing mass. For instance, if you fell in feet first, your feet would be yanked downwards harder than your head, although overall the experience would probably be very short, as you’d be pulled apart into a molecular “piece of spaghetti” before being crushed into the black hole itself. You’d technically be adding more mass to the black hole too, making it ever-slightly bigger than it was before.

 

Source: Scientists observe supermassive black hole in infant universe, Phys.org

On November 27th, 2017 we learned about

High-speed dust could help spread life throughout outer space

What are the odds that we’re all alien life forms? Even if your family has been in your home town for generations, there’s a chance that all life on Earth originated elsewhere, and was somehow transported to this planet billions of years ago. The idea is known as panspermia, and is usually based around the notion that a large asteroid broken off or expelled from a planet carried some hearty organisms along through space, eventually crashing into Earth where those organisms spread and diversified. A new wrinkle in this model is being suggested now, as simulations have found that a large rock may not have been a necessary component for life to travel— biological particles in a planet’s upper atmosphere may have been able to be launched by dust alone.

While there’s not enough air to breath in space, it’s not a complete vacuum either. In addition to larger and smaller asteroids, there’s a fair amount of dust that either never coalesced into a larger object, or was broken off a larger object in a collision. Researchers from the University of Edinburgh found that some of that dust is zipping along at a brisk 156,586 miles per hour, giving them a significant amount of energy to shove other particles that might be suspended high above a biologically active planet’s surface. For example, if a microscopic organism was suspended 93 miles over the Earth’s surface, around the altitude of auroras, a collision with space dust could knock it past the planet’s gravitational pull towards a new home (assuming it survived the collision.)

What life could survive in space?

Once biological material was on its way, the trip might be easier to survive than you’d think. Some bacteria have been found to survive in the generally hostile environment of outer space, and plants and animals do better than expected as well. However, a living creature wouldn’t be strictly necessary to seed life on a new planet. Even the delivery of organic molecules like amino acids would make a huge difference in kick-starting an ecosystem, some of which have already been linked to meteorites found on Earth. If these molecules could be sent sailing from mere dust as well, then the possibilities really open up for interstellar pollination.

Source: Space dust may transport life between worlds, University of Edinburgh News

On November 15th, 2017 we learned about

Climate models that explain colder conditions on dwarf and exoplanets

As the Earth struggles with atmospheric warming, scientists are finding mechanisms that are actually cooling more distant worlds. Unfortunately, they’re not systems that we could reproduce to deal with our greenhouse gas problem on Earth, but understanding what chills the atmospheres of these distant bodies will likely help with the search for habitable worlds in other solar systems.

Pluto is colder than we calculated

Everybody knows that Pluto is cold, but the dwarf planet still surprised scientists with just how cold it really was. Remote measurements of the elements in Pluto’s atmosphere suggested that the Sun should warm its surface to around -343° Fahrenheit, but that isn’t what the New Horizons spacecraft measured when it flew by in 2015. Instead, more direct measurements found that the atmosphere was a frosty -397° Fahrenheit. Over the last two years, researchers have been looking through the collected data to see what could account for this temperature difference.

The current hypothesis is built around the size of the particles in Pluto’s atmosphere. Most atmospheres are made of gas, meaning the atoms and molecules suspended in the sky are tiny and fairly energetic. Pluto seems to have some larger hydrocarbon particles in the mix though, suspended as solid crystal structures instead of gases. Even though these particles are small enough to be measured in nanometers, they’re big enough to interact with heat from the Sun in an unusual manner. Instead of trapping heat against the dwarf planet’s surface like a greenhouse gas, they’re likely absorbing heat from the Sun and surrounding atmosphere, then radiating that heat back into space. This means that the heat is essentially reflected before it has a chance to warm Pluto up.

Heavy snowfall on a hot planet

While Pluto’s hydrocarbon haze may be an effective heat shield, the exoplanet Kepler-13Ab uses similar mechanisms in even more extreme circumstances. The giant planet has a close orbit around its star, Kepler-13A, and thus doesn’t doesn’t rotate like the Earth does on a daily basis. This leaves one side of the so-called “hot Jupiter” in constant daylight, raising temperatures as high as 5,000° Fahrenheit. The night side is then left in permanent darkness, with temperatures dropping appropriately.

Kepler-13Ab was found to have titanium oxide (TiO) in it’s atmosphere, which by itself isn’t unusual for a gas giant planet. Usually this leads to higher temperatures in a planet’s upper atmosphere, as the TiO acts like a greenhouse gas more or less, collecting and emitting heat. Kepler-13Ab changes that formula thanks to its immense gravity, which is six-times greater than Jupiter’s. So instead of remaining in the sky as gases, the planet is pulling some TiO down on its cold, night side as larger particles, almost like a form of snow. As the snow gets pulled down, it takes some heat away with it, lowering the maximum temperature in the upper atmosphere. Without Kepler-13Ab’s intense gravity, the particles would be more likely to recirculate in the atmosphere again, redistributing heat.

Nobody is planning to visit Pluto or Kepler-13Ab any time soon, but these extreme climates will help us as we search for more temperate planets. Being able to understand all the variables that can influence a planet’s climate, including less obvious factors like gravity and particulate size, will make it easier to identify the more subtle conditions that could make some planets pleasant place for life to take root.

Source: Astronomers discover sunscreen snow falling on hot exoplanet, Phys.org

On October 26th, 2017 we learned about

For the first time, astronomers spot an interstellar asteroid flying through our solar system

Our solar system had a guest this week. A small object, most likely an asteroid, was detected zipping past the Sun, dipping below the orbital plane of our local planets and asteroids, then being rocketed up past the Earth at over 97,000 miles-per-hour. It’s exact path is still being pinned down, but at this point it looks like A/2017 U1 is the first object to be observed passing by our Sun while originating somewhere outside our solar system.

Sharp turn just past the Sun

A/2017 U1 was first spotted by the University of Hawaii’s Pan-STARRS 1 telescope on October 19th. It was actually photographed the night before as well, but it wasn’t recognized as something special until the following day when it’s unusual trajectory was detected and analyzed. Rather than following the orbital plane that most of the objects in our solar system move along, this new object was seen diving almost directly at the Sun, and it was doing so very quickly, at around 56,000 miles-per-hour. This high speed is probably what allowed it to slip past the Sun at inside Mercury’s orbit without getting pulled in the Sun, or being vaporized by its heat.

The Sun’s gravity did get a hold of the small visitor, which is estimated to only be around 525 feet in diameter. Even with all the momentum it had to get past the Sun, that small mass was whipped around in a wide, hyperbolic orbit. This means that rather than continue straight through our solar system, the asteroid went “beneath” the planets’ orbital plane then curved around to fly back “up” between Earth and Mars. The hyperbolic shape of this path is open enough that A/2017 U1 isn’t expected to ever return, basically being accelerated in a gravity assist from the Sun without getting caught in a permanent orbit.

First observed object without an obvious orbit

Obviously, we’re not going to get a ton of data about this small rock that, as of this writing, is already over 31 million miles away from Earth. Still, even during its quick visit, we were able to observe it enough to determine that A/2017 U1 is most likely an asteroid, and not a comet as originally assumed. Beyond its physical characteristics, simply spotting this object is a big step for astronomers. With the mind-boggling number of objects in the universe, it’s long been assumed that there must still be some objects that weren’t caught in orbit around larger planets or stars, traveling between solar systems with no real point of origin to speak of. Scientists have observed at least one comet that was in the process of exiting our solar system thanks to a push from Jupiter’s gravity, but that comet may have been home grown. A/2017 U1 finally provides prove that this untethered objects are out there.

Source: Astronomers Spot First-Known Interstellar “Comet” by Kelly Beatty, Sky & Telescope

On October 19th, 2017 we learned about

Frozen pee may be a practical reference point in our future search for life on Enceladus

In 2005, the Cassini spacecraft captured images of plumes of icy water erupting from Saturn’s moon, Enceladus. Subsequent flybys and sampling have suggested that this moon may be habitable by some form of life in its sub-surface ocean, thanks to geological heating. However, this is all inconclusive at this point, because Cassini wasn’t designed to tackle this kind of mission. Even when the spacecraft was flown through the moon’s icy geysers, it could only sample a limited portion of the ejected slush, since the probe could only detect one size of ice grain at a time. Now that Cassini has been crashed into Saturn, researchers are hoping to get another probe to Enceladus, but they need to make sure it’s ready for the job, and that means developing a better understanding of frozen water when it’s flushed into space.

In better tailor sensors for the icy ejecta of Enceladus, engineers would like experiment with, or at least observe, water as it flows into the cold vacuum of space. Of course, water is heavy and therefore expensive to get off the ground, plus astronauts value it as a way to stay, you know, alive. So rather than fly water up to space only to toss it out, it’s been proposed that we start paying closer attention to how wastewater from astronauts’ toilets as well as fuel cells, behaves when it’s vented from spaceships. Wastewater, or any water, spewed from a small metal tube wouldn’t be a perfect proxy for the vents of Enceladus, but it may be a starting point for measuring what kind if ice crystal distribution should be expected.

Previous work with purged pee

There’s also some precedent for these observations. In 1989, researchers used a telescope in Hawaii to watch as the space shuttle Discovery dumped water from its fuel cells. They couldn’t develop a full 3D model from these observations, but they could at least note that two sizes of ice grain formed. Bigger pieces of ice formed right out of the vent, while smaller grains, probably from recondensed water vapor, formed further away. The space shuttles also ejected liquid waste while on missions, although they made sure to keep the astronauts poop for later disposal back on Earth. Some of this vented liquid was found to form long icicles just outside the vents, suggesting another phenomenon that could be found on Enceladus.

While space shuttles dumped liquids more often, the International Space Station doesn’t quite provide the same opportunities to observe frozen pee. Pee isn’t sprayed into space as much anymore, partially due to the realization that frozen urine ejected from the Mir space station in the late 1980s had been slowly damaging the facility’s solar panels. Instead, most of the astronauts’ pee is cleaned and recycled into drinking water, leaving only the most concentrated, briny, urea to be purged into space. Astronauts’ poop doesn’t get tossed out either, but is instead packaged with other bundles of trash that are dropped into the natural incinerator that is the Earth’s atmosphere.

With these limitations, it’s not clear how much we’ll learn by watching astronaut’s waste water. At the very least, the stuff humans flush can at least provide a basic reference point for what to expect the next time we’re near Enceladus.

Source: Astronaut wee could show us how the plumes on Enceladus work by Leah Crane, New Scientist

On October 16th, 2017 we learned about

Gravitational waves help scientists spot the collision of two neutron stars

My daughter loves hearing about astronomy, as the movement of the planets, the unfathomable scale of the universe, and unanswerable questions like “is the universe contained in something?” really excite her imagination. So with today’s announcement that astronomers had finally observed the collision of two neutron stars, it seemed like the perfect story to share with her. If only we hadn’t gone out for candy-laden frozen yogurt an hour earlier…

Me: So once up on a time, two stars blew up.

Four-year-old: That’s bad.

Eight-year-old: It happens eventually to all stars, right?

Me: Well… many of them? The point is the stars were the right size to use up all their full, supernova and be left as neutron stars.

Eight-year-old: What’s a neutral star?

Me: “Neutron,” but that’s a good connection to make. A neutron star is the remains of a star that’s basically made of neutrons, which is a neutrally-charged part of an atom, as compared to positive protons and negative electrons. Anyway, the important thing here is that a neutron star is incredibly dense. You remember density?

Eight-year-old: That means it’s… hot?

Me: No, it’s not about how much energy it has, but how tightly packed together all of it’s material is. So in this case, imagine something that if you put it on Earth somehow would weigh more than our Sun, but was small enough to fit in a space between San Francisco and the San Francisco Airport.

Kids together: Whooooaa…

Me: Yeah, it’s so packed together that–

Eight-year-old: But is it hot?

Me: Well, it’s not inert. It has some some energy as we’ll see, but I’m not sure about its temperature. [Post-bedtime fact-check: Neutron stars are hotter than Earth, but cooler than most stars.]

So the mass of a neutron star is so dense that a teaspoon full of neutron star would weigh a billion tons. They’re a ton of stuff in a small amount of space. But all that ‘stuff’ means that they have a lot of gravity, which is imporant when these two stars started circling each other. As they drew closer, they started orbiting each other, but also tearing each other apart.

Kids: Oooo….

Me: As they spun closer and closer, their immense collective mass started emitting gravitational waves. Do you remember the last time we heard about those?

Eight-year-old, now hanging upside-down off the couch: Uh….

Me: We last heard about this when new sensors detected two black holes crashing into each other. The impact send out waves that were basically warping the universe just a tiny bit, and sensors at two seperate buildings were set to notice when lasers were stretched a tiny bit?

Eight-year-old: Oh right!

Me: Well, those two facilities were called LIGO [Laser Interferometer Gravitational-Wave Observatory], and now a third set of sensors has been set up in Italy, called VIRGO, which is doing the same job. To get back to our neutron stars, we know that 130 million years ago, the two stars finally collided, because the waves from their collision arrived at the Earth, and were picked up by these sensors, around two months ago.

Eight-year-old: Two months ago?!

Me: The collision was very far away- around 130 million light-years. The cool thing was that when the gravitational waves were detected, people were notified to jump into action and start looking for the light that they were expecting to follow.

This kind of collision had been predicted, and the size and shape of the gravitational waves looked like what people expected of crashing neutron stars. So they thought that, unlike a black hole, there’d be some light for telescopes to see. Lots of people at observatories around the world started scanning the sky to find traces of the exploding neutron stars, which is called a kilonova.

Four-year-old: What’s an observatory?

Me: A place with a high-powered telescope.

Eight-year-old: Does that mean it was in the sky the before? Did the constellation [Hydra] change?

Me: They did get to see it, but it wasn’t previously visible.

Many, many teams started working together to look for the colliding neutron stars. One guess is that 25 to 30 percent of all astronomers on Earth helped out with this to get as much information from different telescopes as possible. Finally, someone [Charlie Kilpatrick] from UC Santa Cruz, nearby, found a new bright spot near another star. He told everyone to “look over here!” and you could see a blip appear over time. First it was blue, then red, and then dimmed away to nothing.

It was emitting light, but also something called gamma radiation, which is just a form of energy. We can’t see it, and it usually just flys right through us without doing anything. A lot of it was released in the collision, which is what all the telescopes were really looking for.

We had talked about what it meant to be an “author” on a paper the other day, right? Well, one of the papers about this event has about 3,500 authors on it because so many people helped out.

Eight-year-old: You’re like an author, right Daddy?

Me: Well, not like that kind of author.

Eight-year-old: But you write about science stuff.

Me: But I’m not contributing to experiments or anthing. It’s different…anyway…

Eight-year-old mumbling something…

Me: Because there was so much mass and energy between the two stars, when they smashed together they could essentially make a lot of new atoms. Not making them out of nothing, but recombine material to make new atoms that don’t get created all that often. Most new atoms made by stars are light, like hydrogen, but in this case the neutron star was making heavy metals, meaning silver, gold, platinum, and…

Eight-year-old: Gold?! Oh! Money money money money money…

Me: Uh, yeah. They estimate that there was probably so much gold created in this collision you could ball it up into something the 10 times the size of Earth.

Both kids: Whoaaa….

Eight-year-old: You could be soooo rich!

Me: If you could do something with it, yeah. We use gold for lots of stuff, like some of Mommy’s jewelry, or inside electronics like cell phones, and–

Four-year-old: I want to see Mommy’s jewelry!

Eight-year-old, upside-down again: Inside phones?! Money money money money money…

Me: Ugh… right. So to have any of these metals on Earth means that before the Earth was formed, other neutron stars must have collided and released all these metals, some of which got bundled with the other rocks and dust that eventually clumped together to form the planet. We now dig these things out of the ground to use for all sorts of stuff, like earrings or even dipping strawberries

Eight-year-old: People do that? What?!

Me: Yeah, we put use gold for all kinds of things, but my point is that none of it was from Earth originally. It all came from these huge explosions in space!

Eight-year-old: …my friend said she bought gold for two dollars. Is that real?

Me, realizing I’ve totally lost my audience: If it was a small amount. Two-dollars worth of gold.

Eight-year-old: So it’s made up? The price?

Me: Prices are only what we decide… look, people predicted this is where these heavy metals came from, and now for the first time we’ve been able to observe that happening. We’ve never seen neutron stars colliding before! This work also helps us learn about the expansion rate of the universe, because we can now compare the speed of the gravitational waves to the speed of the gamma radiation. It’s also an amazing project to have so many people working as a team across the globe in a way that just wasn’t possible before!

Eight-year-old: …

Me: You know, platinum is worth more than gold per ounce?

Eight-year-old: Money money money money money…

Me: Bed time?

Source: In a First, Gravitational Waves Linked to Neutron Star Crash by Nadia Drake, National Geographic