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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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Space
The Fascinating Device Astronauts Use to Weigh Themselves in Space

Most every scale on Earth, from the kind bakers use to measure ingredients to those doctors use to weigh patients, depends on gravity to function. Weight, after all, is just the mass of an object times the acceleration of gravity that’s pushing it toward Earth. That means astronauts have to use unconventional tools when recording changes to their bodies in space, as SciShow explains in the video below.

While weight as we know it technically doesn’t exist in zero-gravity conditions, mass does. Living in space can have drastic effects on a person’s body, and measuring mass is one way to keep track of these changes.

In place of a scale, NASA astronauts use something called a Space Linear Acceleration Mass Measurement Device (SLAMMD) to “weigh” themselves. Once they mount the pogo stick-like contraption it moves them a meter using a built-in spring. Heavier passengers take longer to drag, while a SLAMMD with no passenger at all takes the least time to move. Using the amount of time it takes to cover a meter, the machine can calculate the mass of the person riding it.

Measuring weight isn’t the only everyday activity that’s complicated in space. Astronauts have been forced to develop clever ways to brush their teeth, clip their nails, and even sleep without gravity.

[h/t SciShow]

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Space
7 Surprising Facts About Pluto
NASA/JHUAPL/SwRI
NASA/JHUAPL/SwRI

Pluto, the ninth planet of the classical solar system was, until 2015, largely a mystery—a few pixels 3.6 billion miles from the Sun. When NASA's New Horizons spacecraft arrived at the diminutive object in the far-off Kuiper Belt, planetary scientists discovered a geologist's Disneyland—a mind-blowing world of steep mountains, smooth young surfaces, ice dunes, and a stunning blue atmosphere. To learn more, Mental Floss spoke to Kirby Runyon, a planetary geomorphologist at the Johns Hopkins University Applied Physics Laboratory and a scientist on the NASA New Horizons geology team. Here is what you need to know about Pluto, the small world with the biggest heart in the solar system.

1. 248 EARTH YEARS = 1 PLUTO YEAR

At 1473 miles in diameter—about half the width of the United States—Pluto is the smallest of the nine classical planets and the largest discovered "trans-Neptunian object" (i.e., an object beyond the planet Neptune). As could be expected, it is cold on Pluto's surface: around -375°F. Its gravity is about 1/15 that of Earth. It has five moons: Charon, Nix, Hydra, Kerberos, and Styx. Charon is the largest of the moons by far, with a diameter about half that of Pluto. It takes about 248 Earth years for Pluto to circle the Sun, and during that time, its highly elliptical orbit takes it as far as 49 astronomical units from our star, and as close as 30.

2. THE DISNEY DOG IS CONNECTED TO THE PLANET.

Pluto the planet was discovered on February 18, 1930 by astronomer Clyde Tombaugh at the Lowell Observatory in Flagstaff, Arizona. It was named later that year by Venetia Burney, an 11-year-old girl in England. She first learned of the new, nameless planet from her grandfather, who mentioned it while reading the newspaper. Burney was interested in Greek and Roman mythology at the time, and she immediately suggested Pluto.

Her grandfather was impressed, and mentioned it in a note to a friend of his, who taught astronomy at Oxford. The astronomy professor passed word to Lowell Observatory, and the astronomers there took an immediate liking to it. It helped that the first two letters of Pluto are the initials of the observatory's (then dead) founder, Percival Lowell. Note that Burney did not get the name from the Disney dog. Just the opposite: The dog, which premiered the same year as Pluto was discovered, was likely named by Walt to ride the planet's publicity wave. Scientists and cartoonists alike have yet to explain how the then-unseen planet and dog ended up being more or less the same color.

3. A PLUTO SYSTEM SPACE ELEVATOR IS TECHNICALLY POSSIBLE.

Space elevators are a science fiction staple, and advances in carbon nanotubes have made their prospects, if not likely, then certainly possible. The idea is to bring a large object such as an asteroid into a geostationary orbit at Earth's equator, and essentially connect that object and the Earth with a cable or structure. You could then lift things into orbit without the need for rockets. According to Runyon, the unique orbital characteristics of Pluto and Charon create interesting opportunities for the very, very distant future of engineering.

The two worlds are tidally locked. Charon's orbit is precisely the same duration as Pluto's rotation, meaning that if you stood on Pluto's surface, the moon would hover over the same spot, never rising or setting. "Because they are binary, tidally locked, literally orbiting each other in a perfect circle, you could build a space elevator that goes from one planet to the other, from Pluto to Charon," Runyon tells Mental Floss. "And it would touch the ground in both places, physically linking them. And you could literally climb a ladder from one to the other."

4. ITS HEART IS IN THE RIGHT PLACE—THE 40 PERCENT OF THE PLANET WE'VE SEEN.

In 2015, the New Horizons spacecraft arrived at the Pluto system and turned a few pixels into a real world. The famous first image released by NASA is not a straight-on shot from Pluto's side, with the top being the North Pole and bottom being the south. It is in reality a view from Pluto's higher latitudes, looking down. (The heart, in other words, is quite higher up on the planet than the picture suggests.) Because New Horizons was a flyby craft and not an orbiter, planetary scientists don't know what 40 percent of the planet looks like.

5. ITS BIZARRE ORBIT AND ROTATION ARE A MYSTERY.

The traditional classroom solar system model of a light bulb as the Sun and planets on wires extending from it represents a nice flat orbital plane known as the ecliptic, and for most of the solar system, that's pretty close to the truth. But not for Pluto, which has a 17-degree inclination relative to the ecliptic. Moreover, like Uranus, its rotation is tipped on its side, and it rotates backward (east to west). No one knows why, according to Runyon. "It's probably the result of an ancient impact," he says. "One not strong enough to disrupt planet but enough to tip on its side. This might have been the Charon-forming impact, which would be similar to how our moon is formed."

6. WE WERE WRONG ABOUT ITS ATMOSPHERE …

Astronomers have long known that Pluto has an atmosphere. During stellar occultations (that is, when it moves in front of stars), astronomers can see the star dim, and then completely go out, and then reappear dimly, and then return to its full brightness. That dimming is caused by the planet's atmosphere. Astronomers are furthermore able to track its density over time. Because Pluto is so far from the Sun, the ice on its surface sublimates: It goes from a solid directly to a gas without first becoming a liquid. When Pluto reached perihelion (as close to the Sun as its gets in an orbit) in 1989, the expectation was that the atmosphere would begin to collapse entirely: that it would freeze out, basically, and fall to the surface.

"A good comparison is when it snows on Earth," says Runyon. "Snow is basically the water vapor in the atmosphere freezing out and falling to the surface, leaving Earth's atmospheric density slightly lower than it would be otherwise." In Pluto's case, the thought was that the complete atmosphere would freeze out and fall onto the planet's surface.

It didn't happen. "Pluto's atmosphere is denser than we thought it would be," Runyon explains. "Even now as it's moving farther from the Sun, its atmosphere is puffier than ever." One model says that while the atmosphere does thin as ices fall to the surface, it never completely freezes and falls.

7. … WHICH IS ELECTRIC BLUE.

Scientists on the New Horizons team didn't expect to see Pluto's atmosphere during the flyby. "When we spun New Horizons around after closest approach and looked back at Pluto—being basically backlit from the Sun—we could see the atmosphere," he says. "We knew we'd be able to detect it, but to see it, and to see that the sunrise and sunset on Pluto is this ethereal electric blue—nobody anticipated that." Runyon says that the New Horizons found discrete atmospheric layers that could be traced for hundreds of miles. "Pluto has what's called a stably stratified atmosphere. The coldest layer is on the bottom and it gets warmer as you go up," he says.

"In science, you test hypotheses, but before you can even do that you need to figure out what's there in the first place. To me, that's the most exciting part of science. The most exciting part of space exploration is to see something for the first time, and that's what New Horizons was. And to turn around and look back at the Sun and see a beautiful atmosphere with the gorgeous layers through it is just astonishing," he says. 

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