There’s nothing like the farthest reaches of outer space to inspire a sense of mystery and wonder in people. That said, some of the secrets of the universe aren’t exactly as pleasant as we’d hope!

That’s the case with these 26 facts about the cosmos that most people have no idea are true. Some are legitimately creepy, others are downright gross… but after you hear them, you’ll likely start reconsidering that one-way ticket to the Mars colony!

1. Space can alter your DNA: You may have heard of astronaut Scott Kelly (right), who spent a year on the International Space Station while his identical twin brother, Mark (left), remained on Earth. Not only did Scott become taller, but even his genes had changed. Technically, they’re not identical anymore!

2. The universe’s average temperature is a little more than absolute zero—and it’s getting colder: Global warming is a major concern on Earth, but that’s not the case for the rest of the universe. Elsewhere, it’s closer to -455 degrees Fahrenheit, and it’s becoming chillier as the universe expands.

3. It’s impossible to cry in outer space: In the outer reaches of the atmosphere, tears can’t fall. Instead, they linger and build up in your eyes before forming a bubble and floating off. In other words, maybe Interstellar isn’t the most accurate space movie.

4. A supermassive black hole is currently charging through space at three million miles per hour: It’s millions of times heavier than the sun, and it originated more than four billion light years away from an even larger galaxy!

WilyD / Wikimedia Commons

5. Time moves more quickly on Earth than in outer space: Long before space travel became a reality, Einstein proved that “time dilation” is real. Turns out, Earth’s orbit gives the lifeforms living on it an extra second every week.

 6. It’s entirely possible to drown in a spacesuit: In 2013, astronaut Luca Parmitano suffered a malfunction with his equipment, causing the water it was storing to spill into his suit. Thankfully, his fellow astronauts saved him before it was too late.

Naz

7. It’s possible for galaxies to “eat” each other: In a process known as “galactic cannibalism,” large galaxies will sometimes swallow smaller ones, merging the two in the process. Can you imagine if this happened to our beloved Milky Way?

8. Just a month into orbit, pieces of your feet fall off and get lost forever: Luckily, astronauts have reported that this tends to only happen to the calloused parts of their feet. That’s one way to get a pedicure outside of the Earth’s atmosphere!

NASA/Scott Kelly / Wikimedia Commons

9. One day, there will no longer be lights in the night sky: You don’t have to worry about that happening anytime soon. Scientists say that the sky may no longer be populated by stars and planets trillions of years from now… and who knows what’ll become of humanity (or Earth) by then?

William Prost / Flickr

10. There’s no telling when a meteor could reach Earth and strike a human: In 2013, without warning, a meteor struck Russia’s Ural Mountains and the debris from the collateral damage ended up injuring hundreds of people.

11. Planets can be destroyed by bursts of gamma radiation: Experts claim that this is unlikely to happen to our own planet, but according to scientists, gamma ray bursts do have the potential to do so.

NASA / Wikimedia Commons

12. Some billion years from now, the entire universe could literally blow up: You and literally everyone you know will be long gone by the time this happens, but scientists say a “dark rip” is tearing the universe apart, atom by atom, and one day it will all explode.

13. There is a real Earth 2 (sort of), and it’s terrible: The idea of an “alternate Earth” is common in science-fiction. But 20 light years away, there’s a real “exoplanet” called Gliese 581g. Amazingly, it might be able to sustain life, but with extreme temperatures and a red sky, we’re still better off on Earth 1!

14. Journeys into space can make you nearsighted: In just one of a few examples of the way space can alter the human body, fluid from your brain can increase and make your eyes swell. As a result, you might need glasses by the time you return home, even if you had 20/20 vision.

15. Technically, in space, people can hear you scream… and it’s not pleasant: Sound doesn’t work the same way in space as it does on Earth, but there are some unsettling things you definitely can hear (aside from potential screams), like exploding stars!

16. Outer space has an unbearable stench: It’s been compared to everything from raspberries and rum to fried steak to hot metal and sulfur. Those may not all sound terrible individually, but the combination all at once sounds downright gross!

Jeremy Tarling / Flickr

17. Fecal matter floats: The astronauts of the Apollo 10 may not have been sufficiently prepared for the fact that the crew’s poop, as affected by their diets, was bouncy and sponge-like. So they had a huge problem when it got loose from the container!

18. Rogue planets are closer to Earth than the nearest star: You may not have heard of these giant masses floating freely in space, but that might need to change. There may be billions of rogue planets in the Milky Way alone!

Ron Miller / Wikimedia Commons

19. Technically, you live inside the sun: Because we’re so close to the sun’s atmosphere and we experience so much of its heat, we’re more a part of our star than we may realize. In the scheme of the universe, 93 million miles away is closer than it sounds!

20. In space, fires can start from water: In 2014, scientists performed an experiment with “supercritical” water, which was extremely hot and compressed. When combined with organic material, it became a dangerous, fire-like gas. That said, it was helpful for disposing of waste.

21. To the best of our knowledge, we’ve never been visited by any alien lifeforms, even though there may be billions of other planets like ours: Sure, there have been all sorts of claims about UFOs and other extraterrestrial encounters, but none have been confirmed. What gives, aliens?

22. As you sleep in zero gravity, your arms float in front of your face: It could be a disturbing image if you’re not prepared, because it’s so unusual and can look like a stranger is in front of you.

NASA / Wikimedia Commons

23. Everyone and everything on Earth technically moves at 1.9 million miles per hour: That’s because our home planet moves through space that quickly, and we’re just along for the ride! That’s like traveling around the world itself in just five seconds!

24. Something larger than the known universe itself is gradually sucking away portions of our galaxy: Scientists have dubbed this phenomenon the “Dark Flow.” While it’s difficult to understand, you probably don’t have to worry about disappearing just yet!

Aqua Mechanical / Flickr

25. In order to survive in space for an entire year, you’d need to consume at least 730 liters of your own recycled sweat and urine: It may not occur to many people, but water is a limited resource outside the Earth’s atmosphere. You’ve got to take it where you can get it!

26. Global blackouts could be caused by solar superstorms: This almost happened in 2012 when such a storm barely missed Earth. If one hit us, the economic impact alone could be devastating. According to experts, it could cost as much as $2 trillion—or 20 times the cost of Hurricane Katrina.

These facts might make you think twice in case commercial space travel ever becomes available. Still, it can also help you appreciate how many mysteries there still are left to be discovered!

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