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15 Things We’ve Learned About the Universe From the Hubble Space Telescope

Launched 25 years ago, the Hubble Space Telescope is a veritable manufacturing plant of discoveries, solving mysteries of the universe and raising tantalizing new possibilities about where we’ve come from and where we are going. Here are 15 things we’ve learned from the Hubble Space Telescope.

1. WE SHOULD PUT 14 BILLION CANDLES ON THE UNIVERSE'S BIRTHDAY CAKE.  

Galaxies are moving apart, which means at some point they must have been close together. One method to figure out the age of the universe involved using Hubble to determine speed, distance, and acceleration. Scientists could then work out the time necessary for current galactic distances to be reached. The universe's birthday cake requires 14 billion candles.

2. QUASARS CALL GALACTIC CORES HOME.

Quasars are extraordinarily weird. They're the size of our solar system but as bright as entire galaxies that are populated with billions and billions of stars. Scientists used Hubble to track down the home of these celestial high beams: galactic cores.

3. WE CAN SEE "BABY PHOTOS" OF THE UNIVERSE. 

There's no "now" in space. Space is big and light takes a very long time to reach our little corner of the universe. When Hubble peered deeply into space to photograph distant galaxies, scientists were astonished by the number it captured: 3000. But none of the 3000 galaxies pictured in the "Hubble Deep Field" were recent. Hubble literally photographed galaxies from billions of years in the past. (That's how long it took the light to reach us.) In other words, the Hubble Deep Field is comprised of galactic baby pictures from the dawn of time. 

4. WE WERE WRONG ABOUT THE SLOWING EXPANSION OF THE UNIVERSE.

It just makes sense that after the literal eternity which has elapsed since the Big Bang, the expansion of the universe would slow. The Hubble Space Telescope has news for us, though: The expansion of the universe is actually increasing in speed. Why? Dark energy. Of course, we're not even sure what dark energy is, but the working theory is that it's responsible for the acceleration.  

5. PLUTO HAS MORE MOONS THAN WE ANTICIPATED. 

In 2005, scientists discovered two new moons of Pluto using the Hubble Space Telescope. After the New Horizons spacecraft to Pluto launched in January 2006, the possibility of undiscovered moons became a big worry. Unlike planets, small moons can lack the gravity to hold on to their collision debris. A rock hitting a tiny moon might send many more rocks back into space. Because debris the size of a grain of rice could have destroyed New Horizons, the team went to work discovering as many moons as it could. In the end, Hubble discovered four moons around Pluto, bringing its total number to five. New Horizons scientists modeled the newly discovered moons, and were able to avoid disaster.                                                                  

6. WE'RE BEING TREATED TO A CELESTIAL GROUNDHOG DAY.

To those of us without advanced degrees in the subject, physics can seem really weird. There might be nothing weirder, then, than the Groundhog Day supernova. Nine billion years ago, a star blew up. Gravity from intermediary galaxies have bent and influenced light rays from this doomed star in such a way that the light takes different paths to arrive here, some longer than others. This means we've seen the exact same moment in time on more than one occasion. So far, scientists have observed the same supernova four times and counting

7. SUPERMASSIVE BLACK HOLES ARE REAL.

Wikimedia Commons // CC BY-SA 2.5

Einstein predicted black holes with his general theory of relativity, though actually finding them has been something of a problem for scientists. In 1971, Cygnus X-1 was all but confirmed as a black hole, ending years of debate. But around the same time, a new hypothesis was emerging about supermassive black holes that resided at the centers of galaxies. Enter the Hubble Space Telescope, which found in galaxy M87 "conclusive evidence" of the existence of supermassive black holes. It is one of the most astonishing discoveries in the telescope's 25-year history. 

8. IT'S ILLUMINATED THE DETAILS OF EXOPLANETS. 

Exoplanets are planets that orbit distant stars. Many have been discovered, and Hubble has been instrumental in fleshing out what we know about these mysterious worlds. Hubble instruments have performed atmospheric studies of such planets similar to GJ 1132b, a Venus-like world 230 trillion miles away that was just discovered this year. (Atmospheric studies of GJ 1132b itself are still to come.) Hubble has also helped scientists figure out the actual color of an exoplanet—a first. The creatively named HD 189733b is now known to be cobalt blue. (Its color comes not from oceans but from its silicate atmosphere.) Hubble didn't stop there, though. It has also helped scientists create the first exoplanet weather map. The forecast for WASP-43b: hot—3000°F hot—with occasional temperatures reaching a “cool” 1000°F.

9. GANYMEDE HAS AN OCEAN.

Ganymede made quite a splash earlier this year when a subsurface ocean was discovered. But how was that determined, anyway? Scientists used the Hubble Space Telescope to watch auroras on Ganymede. When the auroras didn't behave as expected, scientists knew they had something special. In a statement reported by Space.com, geophysicist Joachim Saur said, "I was always brainstorming how we could use a telescope in other ways. … Is there a way you could use a telescope to look inside a planetary body? Then I thought, the aurorae! Because aurorae are controlled by the magnetic field, if you observe the aurorae in an appropriate way, you learn something about the magnetic field. If you know the magnetic field, then you know something about the moon's interior." In this case, that interior was an ocean. 

10. EUROPA HAS PLUMES, AND THAT MIGHT HELP US FIND LIFE. 

When a world has a subsurface ocean, the great challenge is trying to figure out how to drill down into it and take samples. Plumes make the job much easier. In essence, plumes are giant geysers firing the ocean into space. So instead of spacecraft somehow going into the ocean, plumes help the ocean come to the spacecraft. This is especially important for a world like Europa, which is thought by many to harbor life. In 2013, Hubble scientists discovered plumes on Europa, one of Jupiter's moons. Now that NASA has built a flagship mission around Europa, scientists might soon have a chance at sampling it for life. 

11. THERE ARE NEW WORLDS THAT WE CAN ACTUALLY VISIT. 

The first phase of New Horizons has been successful beyond the dreams of even Alan Stern, the mission's leader. Moreover, the spacecraft still has a lot of power, and its systems are operating at 100 percent. It is presently flying through the mysterious Kuiper Belt—a ring composed primarily of frozen volatiles beyond Neptune—where there is much to learn. The New Horizons team has used Hubble to find new targets for a spacecraft study. If NASA gives the mission extension a green light, the best might be yet to come. 

12. THERE WAS A 10TH PLANET. 

Hubble is good for more than studying exoplanets, moons, and baby galaxies. Scientists have used the space telescope to study strange new planets in our own solar system. Before the International Astronomical Union meddled with the definition of "planet," a tenth planet in the solar system—Eris—was discovered. The secrets of Eris, a Kuiper Belt Object that is now categorized as the second-largest dwarf planet (behind Pluto), were unlocked by Hubble, including its size and mass.                                                                                                

13. THERE IS SUCH A THING AS CLUMPY DARK MATTER.

Thanks to Hubble, scientists have been able to map dark matter in the universe, and have worked out that normal matter (things made of atoms—in this case, galaxies) gathers near dense areas of dark matter. In addition, Hubble's findings suggest that "dark matter has grown increasingly 'clumpy' as it collapses under gravity." NASA compares Hubble's success in mapping dark matter to "mapping a city from nighttime aerial snapshots showing only streetlights. … These new map images are equivalent to seeing a city, its suburbs and country roads in daylight for the first time."

14. IT'S A GALAXY-EAT-GALAXY UNIVERSE.

When scientists used Hubble to study the Andromeda galaxy, they expected to find very old stars. They were surprised, then, to learn that the stars ranged in age from six to 13 billion years old. They suspect that the young stars found their way into Andromeda through cosmic collisions. In other words, Andromeda ate smaller galaxies and kept the stars for itself. 

15. PROTOPLANETARY DISKS ARE OBSERVABLE.

For a long time, scientists believed that "protoplanetary disks"—disks of dust around stars that might form solar systems—would be impossible to see. It was thought that the disks would be obscured by clouds of gas. Hubble proved that suspicion wrong, and has discovered many such disks. As a result, scientists have new insights into how planets and their associated solar systems are created. 

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11 Out-of-This-World Facts About Carl Sagan
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Hulton Archive/Getty Images

Carl Sagan was perhaps America’s most beloved scientific visionary since Albert Einstein. Both a gifted astronomy researcher and an incredible communicator, he brought the wonders of the universe to the masses with his popular TV series Cosmos and books like the Pulitzer Prize–winning Dragons of Eden and Pale Blue Dot. His only novel, Contact, later became a sci-fi movie starring Jodie Foster and Matthew McConaughey. Here are a few things you might not know about the scientist, TV star, and amateur turtleneck model.

1. HARVARD PASSED ON HIRING HIM.

After Sagan served five years at the esteemed university as an assistant professor, Harvard denied him tenure in 1967, in part because one of his mentors at the University of Chicago derided his work as needlessly wordy and useless. He took a job at Cornell instead, where he stayed on as a professor until his death in 1996.

2. HE DICTATED ALL OF HIS WRITING TO AN AUDIO RECORDER.

Carl Sagan standing with a model of the Viking Lander.
JPL via Wikimedia Commons // Public Domain

Sagan was an avid self-editor. A total of 20 drafts of Sagan’s 1994 book Pale Blue Dot exist today in the Library of Congress, each filled with handwritten edits, annotations, and revisions by the author. However, he drafted all of his writing—even grant proposals—by dictating his ideas onto a cassette. The contents were then transcribed for him and returned for editing.

3. HE CONSIDERED WRITING A CHILDREN’S BOOK CALLED HOW DO BIRDS FLY?

In 1993, Sagan brainstormed a long list of possible children’s books for a series structured around the theme of “why?” Other potential ideas included Why Is It Warm In Summer?, Why Are There Lakes?, and What Is Air?

4. HE DIDN’T LIKE THE SPACE SHUTTLE PROGRAM.

Sagan argued against funding NASA’s Space Shuttle program in favor of more robotic exploration of the farther reaches of space. “That’s not space exploration,” he said in an interview about the space shuttle program’s week-long orbits. “Space exploration is going to other worlds.” A space station would only be worth it, he argued, if it was preparing humans for long-term journeys to space, he told Charlie Rose in 1995.

5. HE WAS AN EARLY CRUSADER AGAINST CLIMATE CHANGE.

Carl Sagan with the other founders of the Planetary Society in the 1970s.
JPL via Wikimedia Commons // Public Domain

Sagan’s 1960 Ph.D. thesis concerned the atmosphere of Venus. His theoretical model showed that the planet’s extremely high surface temperatures were due to the greenhouse effect of an atmosphere filled with carbon dioxide and water vapor. In his book Cosmos, he wrote, “The surface environment of Venus is a warning: something disastrous can happen to a planet rather like our own.”

6. HE HAS AN ARCHIVE IN THE LIBRARY OF CONGRESS ENDOWED BY THE CREATOR OF FAMILY GUY.

Part of the Carl Sagan Papers in the Library of Congress.
Paul Morigi/Getty Images

Family Guy creator Seth McFarlane put up an undisclosed sum to help the Library of Congress buy more than a thousand boxes of material kept by the late scientist and his wife and collaborator, Ann Druyan. The papers in The Seth MacFarlane Collection of Carl Sagan and Ann Druyan Archive, which opened in 2013, include some of Sagan’s earliest notebooks and report cards.

7. HE BECAME FAMOUS FOR A PHRASE HE NEVER SAID.

After Sagan appeared in several successful spots on the Tonight Show Starring Johnny Carson, Carson saw fit to send up the scientist’s signature style (turtleneck included) in a parody sketch.

Carson’s exaggerated use of “billions and billions” would later become associated with the astronomer, though he didn’t use it himself. However, Sagan did talk about large numbers quite a lot, as this supercut shows.

8. HE AND ANN DRUYAN DATED FOR ONE PHONE CALL—AND WERE ENGAGED BEFORE HANGING UP.

Sagan and Druyan, who would create the TV show Cosmos together, fell in love while working on the Voyager message. The courtship was exceedingly brief, as NPR's Radiolab describes:

“After searching endlessly for a piece of Chinese music to put on the record, Druyan had finally found a 2500-year-old song called ‘Flowing Stream.’ In her excitement, she called Sagan and left a message at his hotel. At that point, Druyan and Sagan had been professional acquaintances and friends, but nothing more. But an hour later, when Sagan called back, something happened. By the end of that call, Druyan and Sagan were engaged to be married."

9. HE WANTED TO LEGALIZE POT.

Under the pseudonym “Mr. X,” Sagan wrote a 1969 essay for Time magazine about the personal benefits he’d seen from cannabis use. Then in his mid-30s, he admitted to smoking throughout the prior decade. “I find that today a single joint is enough to get me high,” he wrote, going on to observe that marijuana had enhanced his appreciation for art and music. He concluded that “the illegality of cannabis is outrageous, an impediment to full utilization of a drug which helps produce the serenity and insight, sensitivity and fellowship so desperately needed in this increasingly mad and dangerous world.”

10. HE THOUGHT STAR TREK WAS TOO WHITE.

“In a global terrestrial society centuries in the future, the ship’s officers are embarrassingly Anglo-American. In fact, only two of 12 or 14 interstellar vessels are given non-English names, Kongo and Potemkin,” he wrote in a piece about the impact of science fiction on his life in The New York Times in 1978.

11. HE WANTED US TO LEAVE MARS ALONE.

Despite his passion for exploring space, Sagan argued for the preservation of Mars even if it meant limiting our exploration of the planet. In Cosmos, Sagan declared:

“If there is life on Mars, I believe we should do nothing with Mars. Mars then belongs to the Martians, even if the Martians are only microbes. The existence of an independent biology on a nearby planet is a treasure beyond assessing, and the preservation of that life must, I think, supersede any other possible use of Mars.”

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Space
Here's How to Watch NASA's Livestream Spacewalk Series
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NASA, Wikimedia Commons // Public Domain

Like many Americans, astronauts Randy Bresnik and Mark Vande Hei got up and went to work this morning. But instead of an office, their jobs took them on a walk outside the International Space Station. If that sounds more exciting than what you’re doing at the moment, you can watch their progress live on NASA’s website.

The spacewalk, which commenced the morning of October 5 at 8 a.m. EDT and is expected to last over six hours, is the first of three NASA plans to livestream during the month of October. On this mission, Bresnik, Expedition 53's commander, and Vande Hei, a flight engineer, are replacing one of the motorized lathes on the station’s robotic arm. The Latching End Effectors as they’re called are used to grab cargo vehicles and payloads that arrive at the station.

Bresnik has worked aboard the ISS since July and Vande Hei since September. The pair will don their spacesuits again for NASA’s second livestreamed spacewalk of the month on October 10. On October 18, Bresnik will be leading the third spacewalk and he’ll be assisted by flight engineer Joe Acaba. If you missed this event, you can follow NASA Live for more streams of spacewalks, cargo craft launches, and the occasional orbiter disintegrating in Saturn's atmosphere.

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