2019 in space: 25 notable astronomy discoveries in the last year

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December 20, 2019
NASA // Wikimedia Commons

2019 in space: 25 notable astronomy discoveries in the last year

Right now, dozens of instruments, rovers, satellites, telescopes, probes, explorers, and other astonishing technological wonders are floating through space, taking pictures, collecting samples, and even driving around on other planets. Few scientific fields have grown more rapidly and more impressively in the last few decades than the field of astronomy. The branch of science that deals with space, the physical universe, and its many celestial objects is enjoying a golden age right now, with astonishing discoveries piling up every month—and for astronomers, 2019 was a banner year.

Astronomers and other scientists made discoveries in 2019 that test the limits of the human imagination. From star-eating black holes hundreds of millions of light-years away to too-close-for-comfort asteroids hurtling dangerously close to our planet, some of these discoveries were difficult to comprehend even for the scientists who made them. The year 2019 revealed dead stars that are so big they shouldn’t be able to exist, massive ice stores hidden beneath the surface of Mars, and entire galaxies that date back billions of years to the earliest moments of the universe’s birth. Some discoveries will change how scientists collect data, add new pieces to puzzles that have baffled scientists for generations, or help astronomers protect their equipment in space. Other discoveries don’t have any immediate practical applications but are simply so cool that they made headlines around the world.

Stacker consulted numerous astronomy publications, journals, and news sources to find the 25 most notable discoveries or advancements in the field of astronomy in 2019. Some were made by elite scientists at NASA, others by amateurs with their own equipment. Some were made at universities, others were made by man-made machines racing through the cosmos billions of miles away. All, however, are so impressive that they boggle the minds of human beings attempting to contemplate the vast, complex, and mysterious world of outer space.

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NASA/GSFC/Solar Dynamics Observatory

The sun’s new activity

In 2019, instruments on NASA’s Parker Solar Probe relayed some surprising information to scientists back on Earth. The probe found that energetic particles emanating from the sun are much more varied and numerous than previously thought. It’s important information, which could help scientists predict the kind of solar storms that can disrupt space communications equipment.

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NASA, ESA and Erich Karkoschka (University of Arizona)

Saturn’s new moons

In October 2019, astronomers announced that they had discovered 20 previously unknown moons orbiting Saturn. That brought the number of the planet’s known satellites to 82.

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NASA/CXC/JPL-Caltech/STScI/NSF/NRAO/VLA

Impossible black hole

At the end of November, astronomers announced the discovery of a black hole so massive, so enormous, that it shouldn’t be able to exist. This stellar black hole—which forms when dead stars collapse and explode—has a mass 70 times greater than the sun. It was previously believed that black holes could grow to only 20 times the size of the sun’s mass.

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NASA/STScl/ESA // Wikimedia Commons

Black hole triplets

In 2019, a well-known galaxy merger called NGC 6240 revealed a secret. Scientists found three supermassive black holes sharing space in surprisingly tight quarters. In one of the rarest occurrences in the known universe, the composition of NGC 6240 was visibly disturbed by the incomprehensible tug of gravity generated by the trio.

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NASA/Goddard/University of Arizona/Lockheed Martin // Wikimedia Commons

Rock-ejecting asteroid

Around the end of 2018, NASA’s OSIRIS-REx mission arrived at its destination—an active near-Earth asteroid called Bennu. On Jan. 19 and Feb. 19, 2019, astronomers discovered that the top-shaped asteroid was “active,” ejecting rocks and other particles in plumes, with some particles falling and landing back on the asteroid and others getting trapped in its gravitational orbit. It was the first observation of a rock-ejecting asteroid.

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NASA/ESA/Hubble // Wikimedia Commons

Where’s the matter?

In one of the odder discoveries of the year, scientists identified 19 previously unknown dwarf galaxies—but that’s not the strangest part. All 19 were missing dark matter, the mysterious, invisible mass that emits no light but exerts a gravitational pull. Scientists have no idea why the new galaxies are void of dark matter or how a galaxy could exist without it.

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Elmi1966 // Wikimedia Commons

Record-breaking neutron star

Neutron stars are dead stars that met their fate in gigantic explosions called supernovas, and while researchers have long known about them, astronomers have never found one quite as massive as the one they discovered in 2019. Small but extremely dense, neutron stars usually measure only about 12 miles in diameter, but they can have a mass of 100 million tons. This one measures 15 miles in diameter but has a mass 2.14 times greater than that of the sun, which is so massive that scientists previously thought such a find to be impossible.

[Pictured: A pulsar, a fast-rotating neutron star.]

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Canada-France-Hawaii Telescope

Long-distance comet

In 2019, Earth’s solar system received a visitor. A comet from a different solar system—the second one in two years—made a grand entry into Earth’s planetary ecosystem, and no one knows where it came from or how it got here. Called C/2019 Q4, it was first discovered by an amateur astronomer in Crimea named Gennady Borisov.

[Pictured: At center, the Comet C/2019 Q4 as imaged by the Canada-France-Hawaii Telescope on Hawaii's Big Island on Sept. 10, 2019.]

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ALMA // Wikimedia Commons

A giant, ancient galaxy

University of Arizona astronomer Christina Williams noticed a strange glob of light resonating from her instruments one day in 2019—and it turned out to be one of the biggest discoveries of the year. Scientists believe that the light she saw began its journey 12.5 billion years ago from one of the biggest and earliest galaxies in the universe’s history. The previously invisible galaxy gives scientists a glimpse into the infancy of the universe.

[Pictured: One of the most massive known galaxy clusters, RX J1347.5–1145, the center of which shows up here in the dark “hole” in the ALMA observations.]

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NASA/JPL-Caltech // Wikimedia Commons

Three nearby earthly mimics

Also in 2019, scientists at the Institute of Space Sciences in Barcelona, Spain, reported finding three Earth-sized planets orbiting a red dwarf star just 12 light-years away—right around the corner in interstellar geography terms. The researchers believe one of them might have the right conditions to possibly support life.

[Pictured: This artist's concept illustrates a young, red dwarf star surrounded by three planets.]

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NASA/JPL-Caltech/ESA/CXC/STScI

Bubble-blowing Milky Way

In 2019, scientists learned that our galaxy is blowing bubbles. Two giant radio bubbles were observed emanating from near the Milky Way’s supermassive black hole located in the center of the galaxy. Scientists believe the bubbles started forming millions of years ago, and they could provide an explanation for the existence of mysterious magnetized filaments that have long baffled astronomers.

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NASA/JPL-Caltech // Wikimedia Commons

A silent city killer

Alan Duffy of the Royal Institution of Australia was one of the scientists who first discovered Asteroid 2019 OK, a big, fast-moving asteroid that snuck up on them and appeared seemingly out of nowhere. The space rock—which held the potential for so much devastation that scientists dubbed it a “city killer”—missed the Earth by less than one-fifth the distance to the moon.

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Smithsonian Institution // Wikimedia Commons

An ancient molecule

Scientists have long searched for the original building blocks of the universe, and in 2019, they found one. Researchers finally discovered what they believe to be the oldest kind of molecular bond in all of space, a helium hydride ion that represents the earliest bonding of elements created by the Big Bang.

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NASA

18 camouflaged neighbors

NASA’s Kepler spacecraft launched a decade ago with a mission to hunt new planets—and the mission was a raging success. In 2019, scientists digging through Kepler’s treasure trove of data found 18 previously unknown planets roughly the size of Earth hiding in plain sight in the Milky Way.

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ESA/Hubble, M. Kornmesser // Wikimedia Commons

Water on an exoplanet

The first exoplanet—planets orbiting other stars in other solar systems—was discovered in the 1990s. Most of those discovered since—and two-thirds of all planets in total—were discovered during the Kepler mission. In 2019, Professor Björn Benneke of the Institute for Research on Exoplanets at the Université de Montréal reported detecting water vapor—and even perhaps liquid water—on an exoplanet called K2-18b.

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16 / 25
NASA/JPL-Caltech

Odd oxygen on Mars

NASA’s SUV-sized laboratory on wheels known as the Curiosity Mars rover has given scientists more information about the red planet than ever before. Oxygen makes up just a tiny fraction of the Martian atmosphere, and thanks to Curiosity, scientists now know that oxygen behaves oddly on Mars. Scientists discovered that oxygen content increases dramatically in the spring and summer, only to return to normal levels in the fall.

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NASA/Johns Hopkins University/Alex Parker

Photos of Ultima Thule

Scientists discovered a snowman-shaped rock called MU69 in 2014, and it’s been known informally as Ultima Thule ever since. In 2019, the New Horizons probe did a photographic flyby of the mountain-sized object from just 32,200 miles away. That’s a billion miles beyond Pluto and 4 billion miles from Earth, making it the most distant object ever explored up close.

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NASA/JPL-Caltech

Marsquakes

NASA’s InSight lander arrived on Mars at the tail end of 2018. In 2019, its SEIS (Seismic Experiment for Interior Structure) instrument picked up 21 seismic events called Marsquakes—earthquakes on Mars.

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NASA/JPL-Caltech

Magnetism on Mars

Also compliments of the InSight lander, astronomers discovered in 2019 that the crust of Mars is wildly magnetic in some places, with intense magnetic fields emerging and then disappearing. As of today, no one knows what causes this phenomenon.

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NASA/ESA/STScI/G. Bacon

A star with a secret

Far away on the side of the Milky Way opposite of Earth, scientists have found an ancient star that’s packed with evidence relating to the earliest stars created by the Big Bang. Situated 35,000 light-years away from Earth, the red giant contains less iron than any other star in the known Universe, making scientists believe it contains elements from the universe’s original stars.

[Pictured: Red Giant Star as illustrated by NASA.]

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NASA/JPL-Caltech

Light in a black hole

CNN reported in August 2019 that “Astronomers have found a white dwarf star surrounded by a gas disk created from an ice giant planet being torn apart by its gravity.” In one of the most unusual discoveries of the year, scientists learned that the black hole was emitting something that black holes are famous for gobbling up and never letting out—light.

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NASA/JPL-Caltech

Black hole vs. star

NASA’s Transiting Exoplanet Survey Satellite (TESS) caught an epic death battle taking place and relayed what it saw to scientists back on Earth. A distant 375 million light-years away, a so-called “tidal disruption event” was witnessed live when TESS caught an unprecedented viewing of a black hole tearing apart a star that had circled too close to the black hole’s tractor beam of destruction.

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NASA/JPL-Caltech/MSSS

Martian ice

In March 2019, researchers at the University of Texas at Austin reported on the discovery of something very special hidden within Mars. About a mile below the surface of the planet, scientists found massive layers of ice—the frozen version of the key ingredient for life—which is probably the largest store of ice on the red planet.

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NASA/STScl/ESA // Wikimedia Commons

Stellar fireworks

In 2019, the vaunted Hubble telescope was rewarded for its years of hard work with what NASA called “the galaxy’s biggest ongoing stellar fireworks show.” In the mid-1860s, a star that generations of mariners had used to guide their way simply disappeared. Unbeknownst to the sailors, it had become hidden by a massive cloud of dust caused by huge internal eruptions within the star, which culminated in a massive supernova eruption—light from that eruption was responsible for the fireworks.

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NASA/JPL-Caltech/MSSS

Mars’ extinct salt lakes

The Curiosity rover has been exploring Mars’ Gale crater for years, but in 2019, it made a shocking new discovery. The rover found the presence of salt in the ancient lake bed, leading scientists to believe that Mars was once covered in great salt lakes.

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