1. Venus’s day is longer than its year. Venus completes an entire orbit around the Sun before it manages to turn on its axis once. For reference, in Venusian time, World War II ended only 56 days ago.
2. All the stars, galaxies, and black holes in the universe only comprise about 5% of the mass of the universe. As crazy as it sounds, the other 95% is unaccounted for. Scientists decided to label this mystery material “dark matter” and to this day they are still not sure where or what it is.
3. There is an interstellar cloud with over billion billion billion liters of vinyl alcohol, Sagittarius B, which is about 26,000 light years away from Earth. Aside from the distance preventing you from opening an interstellar pub, it’s not really drinkable.  However, it is a very important organic compound that is critical to the existence of life.
4. Right now you are simultaneously hurtling around the sun at 66,600 mph while sitting on a rock that is spinning at 1,070 mph. On top of that, our whole solar system is rocketing through space around the center of the Milky Way at around 559,234 mph.  On top of that, our galaxy is hurtling through space at around 671,080 mph, with respect to our local group of galaxies.  On top of that, for all we know, our entire Universe is hurtling through some unknown medium at some other ridiculous speed.
5. In 2004, scientists discovered the largest diamond ever. It’s a remnant of a collapsed star, measuring 4000 km across and having a core composed of 10 billion trillion trillion carats. It’s also “only” 50 light years from the Earth.  Now we just need to find a way to drag it back to Earth and then find a large chunk of gold to make into the world’s biggest necklace and place it around the Earth with the Diamond attached to the necklace.  That way when Aliens visit, they’ll see Earth’s bling and think we’re uber cool. 😉
6. Saturn floats. As big as the planet Saturn is, if you were to put it in the universe’s biggest glass of water, it would float. This is because its density is .687 grams per cm cubed while water is .998 g per cm cubed. Unfortunately, though, you would need a glass that is over 120,000 km in diameter to witness this.  As with the bling for Earth, humanity should make this happen, and damn the cost, consequences, and technical hurdles that would need overcome.  When aliens visit and see the Earth’s bling, combined with a random planet in our solar system sitting in a giant glass of water, it is likely our solar system would become an interstellar tourist attraction, bolstering Earth’s economy.  Worth it.
7. The U.S. once thought seriously about nuking the moon. Project A119 in the United States was a plan to launch a nuclear missile at the moon. Why? Evidently they felt it would give them a perceptual leg up in the Space Race. Fortunately, however, the plan was never executed.
8. Have you ever wondered why the Moon looks bigger on the horizon?  Well, it turns out it’s not because it is closer to you or anything of the sort.  It’s an illusion, known as the Ponzo Illusion.  What’s happening is actually something that your brain does all the time. Think about what happens when you see one of your friends on the horizon. Although they appear to be really small, your brain doesn’t actually interpret them as being that tiny. Something similar is going on with regards to the Moon. Your brain inflates the size of the Moon to make it appear larger than it really is. Don’t believe it? Next time you’re looking at an over-sized moon, block everything else out with your hands and watch it shrink.
9. Moon dust smells like gunpowder: Upon leaving the Moon, astronauts on the Apollo missions described moon dust as smelling like gunpowder and feeling extremely soft. Scientists, however, are still not exactly sure why this is because the two have extremely different compositions with Moon dust consisting mostly of small shards of silicone dioxide glass.
10. The Big Dipper is not a constellation. While it’s not our intention to burst your bubble, we thought we should inform you that it is actually an asterism. There are only 88 official constellations in the night sky and everything else, including the Big Dipper, falls into this other category. It is, however, composed of the 7 brightest stars in the Great Bear (Ursa Major) constellation.
11. When two like metal objects touch in space, they’ll bond. This is a phenomenon called “cold welding”. While welding usually requires heat, in this case the vacuum of space does the trick, hence the name. You might think then, how do astronauts accomplish anything out there? Well, typically metals on Earth have a layer of oxidized material covering their surface that prevents cold welding, so the risk is negligible.
12. While it only takes 8 minutes and 19 seconds for the light from the surface of the Sun to reach us, it actually takes about 10,000-170,000 years for a photon to travel from the core of the Sun to the surface.
13. The Sun does not have enough mass to go supernova and explode.  However, in about 5 billion years it will enter a red giant phase steadily expanding until it consumes the Earth.  But fear not, the Earth will already be dead in about 1 billion years due to the fact that the Sun becomes about 10% brighter every billion years; so in 1 billion years, the Earth’s surface temperature will be such that no liquid water will be able to exist unprotected on the surface of the Earth.

Source