Discoveries in our solar system helped us become better acquainted with planets like Mars and Venus. Waves of light reached us from across the cosmos to tell ancient stories and reveal new phenomena.
We greeted new worlds that broaden our understanding of planets beyond our little cosmological neighborhood. Extreme celestial objects like black holes gave up some of their secrets while inviting researchers to explore new ones.
Here are some of the discoveries made across the universe in 2021.
The mystique of the red planet
No planet received more of our attention this year than Mars. In February, three separate missions from three different countries arrived at the red planet. Since then, we’ve followed the stories of the UAE’s Hope Probe, China’s Tianwen-1 and Zhurong Mars rover, and NASA’s Perseverance rover and Ingenuity helicopter.
Together, along with other ongoing missions on and around Mars, they have changed the way we see and understand our planetary neighbor. Different spacecraft searched for organic salts, spied colorful clouds and found “significant amounts of water” in Mars’ massive version of the Grand Canyon.
As the Perseverance rover captured video of its own landing, created oxygen on Mars and collected its first samples that will eventually be returned to Earth, the Ingenuity helicopter has and continues to make history with its groundbreaking ability to act as an aerial scout for the rover’s journey long after its first act of powered, controlled flight on another planet.
Swinging by the sun
This year, humans “touched the sun” for the first time using a spacecraft: The Parker Solar Probe.
Since launching in 2018, the mission has been circling closer and closer to the sun. This year, Parker came closer than ever to the sun, entering its outer atmosphere for the first time.
It flew by streaming features in the scorching corona, or upper atmosphere, and helped scientists determine that intriguing zigzags called switchbacks may come from the sun’s surface.
Mercury, Venus and Jupiter
Other planets shared the discovery spotlight with Mars this year as various space missions flew by Mercury, Venus and Jupiter.
Little is known about Mercury because it’s the closest planet to the sun, which makes it harder to observe. The European-Japanese BepiColombo probe conducted a close flyby of the planet in October. It captured images of Mercury that could uncover more about its history, surface and atmosphere.
The Parker Solar Probe flew by Venus during one of its loops as it spirals closer to the sun, taking photos and even detecting a radio signal from the Venusian atmosphere. This year, scientists also discovered that Venus may still be active and gained insight as to why it became a toxic, inhospitable planet rather than turning out like Earth. Future missions from NASA and the UAE were also announced that will further explore Earth’s.
Images and data from the Juno mission continue to rewrite the textbooks on Jupiter and its moons. The spacecraft shared detailed images taken of Jupiter’s moon Ganymede, the subject of a close flyby over the summer by Juno, and even sounds from its atmosphere. Juno also got up close with Jupiter’s famous Great Red Spot to learn more about this centuries-long storm.
Across the Milky Way
Our solar system resides in one of the spiral arms of the Milky Way, but we’re far from fully understanding that sparkling pinwheel.
During the year, we learned the Milky Way is a hub of unusual activity. Researchers detected strange radio waves, observed “violent energy” and spied a blinking star, both at the heart of the galaxy.
A Finish astrophotgrapher completed a scintillating mosaic of the Milky Way after 12 years while scientists mapped a wave of stars in the outer reaches of the galaxy.
Radio bursts reach Earth
Speaking of strange radio signals, scientists discovered hundreds of mysterious fast radio bursts thanks to a Canadian telescope.
Fast radio bursts were first observed by astronomers in 2007, but only 140 or so have been captured across the universe — until this year.
While the origin of these millisecond-long bursts in space remains unknown, the detection of 535 new radio bursts could help scientists map the universe and determine where and how they are created. More than a thousand cosmic explosions were traced back to one fast radio burst that repeats.
In 2021, an international team of astronomers traced some of the bursts to arms of distant spiral galaxies. And giant radio pulses and X-ray surges were found coming from the hauntingly beautful Crab Nebula.
Violence in the universe
A new type of supernova was discovered this year and it provides a unique window into the violent life cycle of stars. The research, focused on supernova 2018zd, confirmed a prediction made by an astronomer more than 40 years ago.
The Hubble Space Telescope captured a rare giant star battling against self-destruction. The star AG Carinae, located 20,000 light-years from Earth, has experienced explosive convulsions that created its distinctive halo, which was beautifully imaged by Hubble this year.
For the first time, astronomers witnessed the death of a distant galaxy. Galaxies die when the stars that live in them stop forming. Scientists were able to glimpse a galaxy as it ejected almost half of the gas it uses to form stars.
Funky asteroids and whizzing comets
Astronomers also found some extreme versions of asteroids and comets across the solar system this year.
New photos shared the most detailed observations yet of the asteroid 216 Kleopatra — an asteroid with two moons that just happens to look a lot like a dog bone.
Then, there was the discovery of the fastest orbiting asteroid in our solar system — an asteroid that completes an orbit around the sun every 113 days and comes within 12.4 million miles (20 million kilometers) of our star.
And prep your telescopes for 2031, when we’ll get a chance to see the largest known comet as it flies by our sun. It’s about a thousand times more massive than others.
Pac-Man black holes
The first evidence of a black hole acting like Pac-Man as it gobbled up a neutron star revealed a theorized but incredibly rare celestial event.
A supermassive black hole was also spotted just wandering through space. And a record-breaking “tsunami” of gravitational waves were detected this year, most of which were produced when black holes merged together billions of years ago and created ripples in space-time.
Above and beyond exoplanets
Imagine a strange world and it likely exists among the weird and wonderful exoplanets researchers discovered this year.
Researchers zoomed in on what worlds may have watched our planet evolve over time and peeked at planetary atmospheres.
They found a new class of exoplanets, called Hycean planets, that are hot ocean worlds which could support life.
Most exciting of all, scientists may have detected the first planet ever to be discovered outside our galaxy.
The possible exoplanet was discovered in the Whirlpool Galaxy, about 28 million light-years away — thousands of times farther away than those in the Milky Way.
