The universe looks like a pretty quiet place to live. But the universe is filled with dangerous things, all struggling to be the one to wipe us off the planet. Happily for us, they're all pretty unlikely, but if you wait long enough, one of them is certain to get us. But which one? 1. Death by Asteroid   Of all the ways we might meet our untimely death, getting wiped out by an asteroid is the most likely. Why? Because we sit in a universal shooting gallery, with 100 tons of material hitting us every day. The problem, though, occurs every few centuries when something big this way comes. If you could ask a dinosaur, I'd imagine they would tell you to take _ seriously. 2. Death by Exploding Star When a huge star ends its life, it does so with a bang, which sends death spreading across space in the form of high-energy radiation. Many studies show that the bang would have to be closer than about 75 light years to do us any harm. The good news: no stars so close are able to do the deed. 3. Death by Dying Sun The sun is important to us; without it, we'd freeze. But the sun is also middle-aged, already halfway to running out of fuel, expanding into a red giant, and cooking us to a fine crisp. Even long before then, it'll warm up enough to raise our average temperature and cause a runaway greenhouse effect, boiling our oceans. Happily, that's a long time from now. 4. Death by Black Hole Black holes are misunderstood. They don't wander the galaxy looking for tasty snacks in the form of planets and stars; they turn around the Milky Way just like the hundreds of billions of other stars do. But it's possible that one could wander too close to us. If it did, planetary paths would be disturbed, causing the Earth to drop into the sun or be thrown out into deep space. Given that it could be trillions of years or more before even that happens, we don't have to worry too much about black holes. My advice? Go outside, look up, enjoy the sun, the moon, and the stars. They may be there forever as far as any one of us is concerned...and forever is a long, long time. Which of the following statement is possible about black holes?
They wander the galaxy. One of them wanders very close to the earth. They turn around the galaxy. They look for planets and stars.