Astronomers Will Soon Have the First-Ever Picture of a Black Hole

The center of the Milky Way galaxy, with the supermassive black hole Sagittarius A*, located in the middle, as captured in x-ray and infrared in this 2013 NASA photo.
The center of the Milky Way galaxy, with the supermassive black hole Sagittarius A*, located in the middle, as captured in x-ray and infrared in this 2013 NASA photo.
NASA/UMass/D.Wang et al., IR: NASA/STScI

It may not be the closest black hole to Earth, but it’s certainly the closest one that astronomers have labeled as "supermassive." Known as Sagittarius A* (pronounced “Sagittarius A-star”), the mysterious object, first detected in the 1970s, weighs as much as 4 million Suns. Formed by the collapse of large stars, most black holes aren't nearly that size.

Sagittarius A* sits at the very heart of the Milky Way galaxy, some 25,000 light-years from our solar system—but until now, we haven’t known much about it. Soon, however, thanks to a globe-spanning array of radio telescopes known as the Event Horizon Telescope, astronomers will have their closest ever look at this enigmatic object.

The Event Horizon Telescope, or EHT, is named for the infamous “point of no return” that marks the outer boundary of a black hole. (The gravity of a black hole is so strong that nothing can escape it, not even light—thus the name.) It incorporates huge, dish-shaped telescopes at six different sites on four continents, including Antarctica and Hawaii. The array recently completed its most ambitious observation so far, collecting data of Sagittarius A* over a 10-day period in mid-April.

“We’ve never had data of the quality that we’ve just taken,” Dan Marrone, an experimental astrophysicist at the University of Arizona, tells Mental Floss. When the data is eventually processed—sometime this fall at the earliest—astronomers will have their clearest picture yet of a black hole.

A VIEW OF THE EDGE

What that image will actually look like, however, is still very much up in the air. We know that black holes are typically surrounded by accretion disks—rings of dust and gas that swirl around the black hole, getting ever-hotter as the material approaches the black hole’s event horizon. The in-falling matter gets so hot that it emits radio waves and other radiation (which is how objects like Sagittarius A* were first detected). Accretion disks can also produce jets—streams of high-energy particles that get blasted out from the black hole at nearly the speed of light. And we know that the system’s intense gravity bends starlight as it passes near the black hole. “We might see a crescent, brightened on one side—or a bipolar, jet-like structure,” Marrone says. “We honestly don’t know.”

Standard optical telescopes—even those high above the Earth’s atmosphere, like Hubble—can tell us very little about objects like Sagittarius A* because there’s too much gas and dust between us and the galactic center for optical wavelengths to penetrate; it’s like trying to peer across San Francisco Bay on the foggiest day of the year.

But radio telescopes, taking advantage of the longer wavelengths of radio waves, can see through the murk. The best bet, astronomers have found, is to use telescopes sensitive to wavelengths of about 1 centimeter—longer than wavelengths of infrared light, but shorter than the waves that your car radio picks up.

Multiple radio telescopes, in different locations, can be made to work together even better, simulating a much larger instrument. This technique is known as VLBI, for Very Long Baseline Interferometry. The Atacama Large Millimeter-submillimeter Array, comprising 66 radio dishes in northern Chile, was recently added to the EHT array, greatly boosting the overall sensitivity; the South Pole Telescope was also added to the array in April. The project now involves 30 institutions in 12 countries.

“The Event Horizon Telescope is going to be zooming in, to right where the inner edge of the accretion disk is falling in to the black hole—right at the boundary between where the disk material ends and the black hole starts,” radio astronomer Joseph Lazio of NASA’s Jet Propulsion Laboratory tells Mental Floss.

A BLACK HOLE WITHOUT MUCH OF AN APPETITE

Of course, we can never see past the event horizon—whatever’s on the other side remains forever beyond our reach. But with the resolving power of the EHT, astronomers will have their closest look yet at the region immediately outside it.

The EHT’s resolving power will be so crucial because, despite Sagittarius A*’s heft, it’s not very large in terms of size. Its event horizon is believed to span just about 15 million miles—less than 20 times the diameter of the Sun.

And in spite of the public perception of black holes as “cosmic vacuum cleaners” that suck up everything in sight, Sagittarius A* is actually not much of an eater. “It’s on a starvation diet,” Marrone jokes. “We don’t know of another black hole that’s eating so slowly, relative to its weight.”

Another target for the EHT will be the black hole in the center of a galaxy known as M87. This ginormous black hole is 1000 times farther away than Sagittarius A*, but it’s also 1000 times more massive; it’s so big that its gravity anchors an entire cluster of galaxies, known as the Virgo Cluster. And it has enormous jets shooting out of its accretion disk—something that astronomers are anxious to get a closer look at.

Beyond simply imaging these giant black holes, the EHT may shed some light on the complex relationship between supermassive black holes and the galaxies that harbor them. Surveys using X-ray telescopes suggest that these overweight black holes are common; they’re believed to lurk in the hearts of most galaxies. But did the galaxies evolve first, and then the black holes—or was it the other way around?

WHAT CAME FIRST, THE BLACK HOLE OR THE GALAXY?

“There’s a very strong correlation between the properties of these supermassive black holes and the properties of their host galaxies,” David Spergel, a Princeton astrophysicist and director of the Center for Computational Astrophysics, tells Mental Floss. “So they’re linked together—but this is a chicken-and-egg question that we don’t know the answer to.”

Another motivation for studying black holes is to determine whether Einstein’s theory of gravity, known as general relativity, correctly predicts the observed physics. The theory, which turned 100 last year, has so far passed every test thrown at it—but it has yet to be tested in the exotic environment adjacent to a black hole event horizon, with its ultra-strong gravitational field. “You’re probing a new regime—and whenever you’re in a new regime, you could be in for a surprise,” Spergel says.

The astronomers working on the EHT won’t see the fruits of their labors right away: Each of the facilities in the array recorded about 500 terabytes of data during this spring’s observing run—far too much to be conveniently sent over the internet. So the data is being sent the old-fashioned way, by shipping bulky drives via FedEx to the EHT’s two processing centers, located in Westford, Massachusetts and in Bonn, Germany. (That doesn’t include the disks from the South Pole Telescope; they’ll be shipped later in the year, when planes can access the site after the Antarctic winter.) Then the data needs to be processed, which will take some six to eight months.

Asked if he was feeling tense, Marrone replied that “anticipation” was a better word; after all the testing he and his colleagues have done, he’s pretty confident that the EHT has delivered the goods. “I’d like to know what we’ve got in those data,” he said. “But it’s going to be a long wait.”

Mapping Technology Reveals 'Lost Cities' on National Geographic

Lin uses his iPad to visualize scanning data of a crusaders' fortress at the lagoon in Acre, Israel.
Lin uses his iPad to visualize scanning data of a crusaders' fortress at the lagoon in Acre, Israel.
Blakeway Productions/National Geographic

Imagine what Pompeii looked like before the lava hit, or Mayan pyramids before the jungle took over. In the past decade, scientists have been able to explore human settlements long since abandoned by using a new wave of accessible technology. Instead of needing an expensive plane and crew to fly aerial sensors, for example, explorers can mount them on cheaper drones and pilot them into previously unreachable areas. The resulting data can tell us more about the past, and the future, than ever before.

That’s the premise of Lost Cities with Albert Lin, a new TV series premiering on National Geographic on Sunday, October 20.

Lin, an engineer and National Geographic Explorer, uses cutting-edge tools to shed light on centuries-old cities in the most beautiful places on Earth. Ground-penetrating radar reveals buried structures without disturbing the landscape. A drone-mounted remote sensing method called LIDAR—short for "Light Detection and Ranging"—shoots lasers at objects to generate data, which Lin visualizes with 3D mapping software. The results suggest what the ruins probably looked like when they were new.

Albert Lin and crew in Peru
Thomas Hardy, Adan Choqque Arce, Joseph Steel, Duncan Lees, Albert Lin, and Alonso Arroyo launch the LIDAR drone at Wat'a in Peru.
National Geographic

“It’s like a window into a world that we’ve never had before,” Lin tells Mental Floss. “It’s shooting millions of laser pulses per second through a distance of air. By digitally removing the top layer of everything above the ground—trees, brush, cacti—you’re washing away the past. All of the sudden you’re left with these fingerprints—experiments in how we organized ourselves through time.”

For the six-episode series, Lin and the expert storytelling team were dispatched to the South Pacific, the Middle East, the Andes, the Arctic, and other destinations. Lin explains that while most of the sites are known to archaeologists, they’ve never been so precisely mapped in three-dimensional detail.

In the first episode, Lin travels to Nan Madol, an enigmatic complex of temples and other structures on the Micronesian island of Pohnpei. With the help of local researchers and indigenous leaders, Lin and the team scan the ruins and digitally erase trees, water, and forest undergrowth to unveil the complex's former grandeur.

“Technology and innovation have always been that gateway to go beyond the threshold, and see what’s around the corner,” Lin says. “Seeing these worlds for the first time since they were left, it’s almost like reversing the burning of the library of Alexandria. We can take the synthesis of knowledge of all these watershed moments of our human journey, and imagine a better future.”

Lost Cities With Albert Lin premieres Sunday, October 20 at 10/9c and resumes on Monday, October 21 at 10/9c on National Geographic.

8 Ways Science Can Boost Your Halloween Fun

iStock
iStock

Halloween is all about embracing the supernatural, but science shouldn't entirely fall by the wayside during the spookiest of holidays. Here are a few ways it can actually improve your holiday, from making trick-or-treating easier to fooling your brain into thinking you're eating tasty treats even though you're nibbling on candy cast-offs.

1. Slow the decomposition of your Halloween jack-o'-lantern.

A Halloween display of five jack-o-lanterns
iStock

You don't have to be an expert gardener to keep your jack-o'-lantern looking fresh all Halloween season long. While scouting out pumpkins, pick hard, unblemished ones and steer clear of those with watery dark spots. These splotches indicate frost damage.

Hold off on carving until right before Halloween so your gourds won't rot—but if you can't resist, try squirting their exteriors with lemon juice after you're done slicing and dicing. The acid inhibits pumpkin enzymes, which react with oxygen and cause browning. A light misting of bleach solution will help keep fungus at bay. Some apply vegetable oil or Vaseline to prevent shriveling and drying. We experimented with various techniques in this video.

For extra TLC, you might even want to bring your jack-o'-lanterns in at night if temperatures dip; if you live in a hot and humid area, extend its life by placing it in the fridge overnight. Try using glow sticks or LED lights instead of flesh-singeing candles.

2. Use apps to plan a treat-or-treating route.

Three children in Halloween costumes trick-or-treating
iStock

Thanks to technology, trick-or-treaters (and their hungry adult companions) can now scout out which neighbors are doling out the best candy and which are sticking with Tootsie Rolls, apples, and toothbrushes. Simply download the app for Nextdoor, the neighborhood-based social network, to check out an interactive "treat map" that lets users tag whether their home is handing out treats, and what that treat is.

Since safety is far more important than sugar, guardians should also consider adding a tracking app to their arsenal come Halloween, especially if their kid's venturing out alone. The Find My Family, Friends, Phone app gives the real-time locations of trick-or-treaters, provides alerts for when they turn home, and also comes with a "panic" button that provides emergency contact details when pressed.

3. Optimize your candy's flavor (even if it's SweeTarts).

Hard candies and gummies strewn across a table
iStock

Not crazy about this year's Halloween loot? Fool yourself into thinking those black licorice pieces and peanut chews taste better than they actually do by eating them after you scarf down the chocolate and Sour Patch Kids. According to a 2012 study published in Psychological Science, being aware that these items of candy are your very last candies actually tricks the brain into appreciating them more (and thus thinking they're tastier than they really are).

Meanwhile, a 2013 study from the same journal found that creating a candy-eating ritual enhances flavor and overall satisfaction. Nibble the ridged edges off a Reese's peanut butter cup before tackling the creamy center, sort the M&Ms by color, and take your time unwrapping a chocolate bar.

4. Create a DIY fog machine with carbon.

Dry ice in a glass bowl
iStock

Save money at Party City by creating your own fog machine at home. When dropped in water, dry ice—or frozen carbon dioxide—creates a gas that's a combination of carbon dioxide and water vapor, but looks like the fog you'd see rolling through a haunted graveyard [PDF].

5. Eat sort-of-heart-healthy Halloween candy.

A stack of dark chocolate chunks on a dark stone background
iStock

Halloween candy isn't always bad for you. While shopping for this year's trick-or-treat bounty, steer clear of sugary confections and milk chocolate mini-bars. Opt for dark chocolate treats instead. Research suggests that our gut microbes ferment the antioxidants and fiber in cocoa, creating heart-healthy anti-inflammatory compounds. Plus, dark chocolate or cocoa also appears to help lower blood pressure for people with hypertension, decrease bad cholesterol, and stave off cardiovascular disease and diabetes, among other benefits.

6. Analyze data on Halloween candy trends and give the people what they want.

Lollipops
5second/iStock via Getty Images

Thanks to data science, you can make sure you're giving out the best treats on the block. Bulk candy retailer CandyStore.com combed through 10 years of data (2007 to 2016, with a particular focus on the months leading up to Halloween) to gauge America's top-selling sweets. They created an interactive map to display their results, which includes the top three most popular Halloween handouts in each state and Washington, D.C. Be prepared for plenty of stoop-side visitors and adorable photo ops.

7. Bake better Halloween treats with chemistry.

Frosted Halloween cookies shaped like ghosts and pumpkins
iStock

Cooking is essentially chemistry—and depending on your technique, you can whip up chewy, fluffy, or decadent Halloween treats according to taste.

Folding chunks of chilled butter into your dough will give you thick, cake-like cookies, as will swapping baking soda for baking powder. When butter melts, its water converts into gas, which leaves lots of tiny holes. If the butter flecks in question are colder and larger, they'll leave bigger air pockets. As for the baking powder, it produces carbon dioxide gas both when it's mixed into the dough and when it's heated. For an extra boost in texture, you can also try adding more flour.

Prefer chewier cookies? Start out with melted butter in the dough, and stick with plain old baking soda.

And for extra-fragrant and flavorful baked goods, opt to use dark sugars—like molasses, honey, and brown sugar—because they're filled with glucose and fructose instead of plain old sucrose. As cookies bake, they undergo two processes: caramelization, in which the sugar crystals liquefy into a brown soup; and the Maillard reaction, a chemical reaction between the dough's proteins and amino acids (flour, egg, etc.) and the reducing sugars that causes tasty browning.

8. Take deep breaths to stay calm in haunted houses.

A brown-haired woman in a red polka dot blouse standing with a frightened expression next to a spider web.
iStock

Halloween can be tough for people with anxiety or low thresholds for fear. While visiting a haunted house or watching a scary movie, remember to take deep breaths, which fends off the body's flight-or-fight response, and reframe your anxiety in your mind as "excitement." It's also a good idea to schedule spine-chilling activities after an activity that triggers feel-good endorphins—say, after a walk to check out your neighbors' awesome Halloween displays.

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