Score
Title
868
How To Search ELI5: A Quick Reminder About Rule 7
14635
ELI5: Why do cars travel in packs on the highway, even when there are no traffic stops to create groups?
8
ELI5 Retarded Time
5
ELI5:Why is eating healthy 80% of being healthy?
3
ELI5: Why are our fingertips, ear holes and nostrils all approximately the same size?
3
ELI5: Why do animals appear to care so much for their young, but not so much when the 'children' get older?
4
ELI5: Why do our eyes lose focus after staring at something for a while?
17
ELI5: SD. SS. SA. Gestapo. Wehrmacht. Sipo. Kripo. What were they all and how do they relate to each other?
10
ELI5: How many ants does it take to make a functioning ant colony?
3
ELI5:How some stars become pulsars?
5
ELI5: Objectively, what are the limitations of carbon dating?
3
ELI5; What is the difference between a break and a fracture?
5
ELI5: Air movement in a house
4
ELI5: How can sperm cells "swim" through something as thick as seminal fluid? You wouldn't be able to swim through honey for example.
4
ELI5: Why can't there be an "universe's point of reference" in relativism?
5
ELI5: Why/how can most species of animals hold their breath underwater for far longer than humans can?
2
ELI5:What causes us to cry in real life when we are crying when we are sleeping?
4
ELI5: How are we able to track debris in low earth orbit so effectively?
3
ELI5: If I use the same amount of coffee grounds but more water, does my caffeine content change?
9
ELI5: Why are cones and pyramids exactly 1/3 of a cylinder or prism's volume?
5
ELI5: What causes exhausts to have that rasp-y sound people tend to associate with tuners? (civics, integras, etc)
2
ELI5: Why is it stated sharks will suffocate if they quit swimming, but I see examples like the white-tipped reef shark who spend the day laying on the bottom?
15
ELI5: When and why did 8 hours of sleep become the standard for a solid night’s rest?
3
ELI5: Why do you always close your eyes while sneezing?
8
ELI5: Why sliding a knife makes a better cut than just pressing it down?
1
ELI5: How a bong works
1
ELI5: Why is it easier to drink from a paper cup than from a glass mug when moving in a car?
43
ELI5: How come smart phones can run intense games without a fan and still not burn the CPU, but a desktop computer can't even load the desktop for more than a few minutes without permanent damage?
1
ELI5: Why do jet skis/jet boats work better when the nozzle is not in the water?
3
ELI5: What is "Mother's Intuition" and/or is it real?
2
ELI5: What causes us to perceive words that we use everyday as mispelled or mispronounced when they actually aren't?
1
ELI5: Why is the term "Patient Zero" instead of "Patient One?"
0
ELI5: How are glasses lenses put into and taken out of the frame without breaking them?
1
ELI5: What does it mean when the European Parliament adopts a report?
4
ELI5: Why Do Hot Things, E.G. Fire, Molten Materials Tend To Emit Light?
2
ELI5:I know from the local game magazine that elk are hunted in PA, however this map from wikipedia shows the entire state as "former" elk range. What criteria are used to determine this if there can still be elk in former ranges?
1
ELI5: Which pixel colors are shown when a high resolution video is played on a low resolution screen?
36
ELI5: Why is ?4 = -2 false?
2
ELI5: Why do bank cheques only have account name?
8
ELI5: Why do certain types of noise enhance our abilities to focus and study whereas others don't?
127
ELI5: If we breathe in O2 and use the oxygen, how do we release CO2? The same ammount of oxygen we took in, just an added carbon atom
13 tlmngz Because of the Sun, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto, asteroid belt, Kuiper Belt, and Oort cloud. Most people assume that asteroids go in a straight line. But what many of us forget is that the gravity of nearby planets affect the trajectory of an asteroid. Even a pull of a body as small as the Moon can drastically affect the direction and speed an asteroid is going, even if it's on the other side of the solar system! Also, nearby stars also have a minuscule, but still measurable, gravitational effect. These effects might only pull an asteroid a couple millimeters in another direction, but over time, these changes add up. Humans don't have enough computational power (yet) to try and compute all these different unknowns. Trying to predict the direction of an asteroid is known as the [N-Body problem](https://en.wikipedia.org/wiki/N-body_problem).
6 Feathring Because that requires knowing it's precise trajectory. Even a minute error in readings over the vastness of space an object will travel can change something like an asteroid impacting earth.
3 WRSaunders They generally can. When a new object is first observed, all the observations are quite near to each other. Since any measurement has uncertainty, the resulting orbital calculations are uncertain. Think of it like two dots a pencil width apart on a piece of paper. The line from the top of one dot past the bottom of the other isn't exactly the same as the line between the bottoms of both dots. If you get across the room, the distance might be big. Alas, space is super huge, and we're talking about a lot more than "across the room". Fortunately, over time, we can make more measurements. When you have two dots on different sides of the room, the angle between these two lines is pretty small. Small enough to see if it intersects an Earth-sized object.
2 SilverShadow5 Gravity is an attractive force between objects. In space, there are lots of objects. Even at great distances, gravity exists between these objects and a specific object. Now, the effect is small. Let's say the moon is inadvertently pulling it closer to the Earth only an inch for every mile it travels along its predicted Earth-only trajectory. Doesn't sound like much, huh? Well, if it's passing by the moon then by the time it passes by the Earth it will have gotten 3 miles closer to the Earth. If it's coming from an asteroid belt, then that 3-miles variance could wind up becoming 300 or even 3000 miles.
1 Loki-L The ones we actually know about are not really the problem. As soon as we have enough observations of an object to know where it is and where it is going how fast, making accurate predictions years and decades and even centuries into the future is relatively easy. Of course tiny uncertainties add up over time. One of the most worrisome candidates for striking the Earth is [(29075)_1950_DA](https://en.wikipedia.org/wiki/(29075%29_1950_DA) an asteroid which has a tiny chance of striking Earth in 2880. It most likely won't but there is a 1 in 9000 chance of it still hitting us. Mostly when a new object gets discovered that might hit earth, we can keep observing it until we are reasonably sure that it won't be a problem. The real problem are the objects that we don't know about. Watching out for potentially civilization destroying Near Earth Objects is pretty much a hobbyist effort by interest volunteers around the globe and we are very far from having discovered all that we could if we put enough resources into the endeavor. We spend more money on making movies about asteroids hitting earth than on looking for actual asteroids that might hit earth. Even worse there may very well be potential impactors that we simply won't be able to see until it is too late. Being able to figure out if the astroid or comet will hit us once we can see it is the easy part, actually seeing it first is a bigger problem.
1 kouhoutek * space is very, very large, compared to the Earth...knowing whether something will hit an 8000-mile target from a billion miles away isn't easy * you have to account for the influence of every large object in the solar system, and that introduces uncertainty * we can barely see the asteroids when they are first discovered, and often don't have enough information to plot an accurate orbit
1 jaa101 The biggest issue for earth-approaching asteroids is usually close approaches to earth itself. These make relatively large changes to the asteroid's orbit. Exactly how large depends on exactly how close they come so each close approach greatly magnifies any uncertainty. Think about throwing a ball up against a flat surface. We can predict where it will go quite accurately. But what if you throw the ball at a circular pole or column. Now, tiny errors in direction will make a huge difference in where the ball goes. Every approach to the earth (or other massive body) is like a ball bouncing off a pole and the uncertainty quickly becomes huge.
14 0 tlmngz Because of the Sun, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto, asteroid belt, Kuiper Belt, and Oort cloud. Most people assume that asteroids go in a straight line. But what many of us forget is that the gravity of nearby planets affect the trajectory of an asteroid. Even a pull of a body as small as the Moon can drastically affect the direction and speed an asteroid is going, even if it's on the other side of the solar system! Also, nearby stars also have a minuscule, but still measurable, gravitational effect. These effects might only pull an asteroid a couple millimeters in another direction, but over time, these changes add up. Humans don't have enough computational power (yet) to try and compute all these different unknowns. Trying to predict the direction of an asteroid is known as the [N-Body problem](https://en.wikipedia.org/wiki/N-body_problem).
5 0 Feathring Because that requires knowing it's precise trajectory. Even a minute error in readings over the vastness of space an object will travel can change something like an asteroid impacting earth.
3 0 WRSaunders They generally can. When a new object is first observed, all the observations are quite near to each other. Since any measurement has uncertainty, the resulting orbital calculations are uncertain. Think of it like two dots a pencil width apart on a piece of paper. The line from the top of one dot past the bottom of the other isn't exactly the same as the line between the bottoms of both dots. If you get across the room, the distance might be big. Alas, space is super huge, and we're talking about a lot more than "across the room". Fortunately, over time, we can make more measurements. When you have two dots on different sides of the room, the angle between these two lines is pretty small. Small enough to see if it intersects an Earth-sized object.
2 0 SilverShadow5 Gravity is an attractive force between objects. In space, there are lots of objects. Even at great distances, gravity exists between these objects and a specific object. Now, the effect is small. Let's say the moon is inadvertently pulling it closer to the Earth only an inch for every mile it travels along its predicted Earth-only trajectory. Doesn't sound like much, huh? Well, if it's passing by the moon then by the time it passes by the Earth it will have gotten 3 miles closer to the Earth. If it's coming from an asteroid belt, then that 3-miles variance could wind up becoming 300 or even 3000 miles.
1 0 Loki-L The ones we actually know about are not really the problem. As soon as we have enough observations of an object to know where it is and where it is going how fast, making accurate predictions years and decades and even centuries into the future is relatively easy. Of course tiny uncertainties add up over time. One of the most worrisome candidates for striking the Earth is [(29075)_1950_DA](https://en.wikipedia.org/wiki/(29075%29_1950_DA) an asteroid which has a tiny chance of striking Earth in 2880. It most likely won't but there is a 1 in 9000 chance of it still hitting us. Mostly when a new object gets discovered that might hit earth, we can keep observing it until we are reasonably sure that it won't be a problem. The real problem are the objects that we don't know about. Watching out for potentially civilization destroying Near Earth Objects is pretty much a hobbyist effort by interest volunteers around the globe and we are very far from having discovered all that we could if we put enough resources into the endeavor. We spend more money on making movies about asteroids hitting earth than on looking for actual asteroids that might hit earth. Even worse there may very well be potential impactors that we simply won't be able to see until it is too late. Being able to figure out if the astroid or comet will hit us once we can see it is the easy part, actually seeing it first is a bigger problem.
1 0 kouhoutek * space is very, very large, compared to the Earth...knowing whether something will hit an 8000-mile target from a billion miles away isn't easy * you have to account for the influence of every large object in the solar system, and that introduces uncertainty * we can barely see the asteroids when they are first discovered, and often don't have enough information to plot an accurate orbit
1 0 jaa101 The biggest issue for earth-approaching asteroids is usually close approaches to earth itself. These make relatively large changes to the asteroid's orbit. Exactly how large depends on exactly how close they come so each close approach greatly magnifies any uncertainty. Think about throwing a ball up against a flat surface. We can predict where it will go quite accurately. But what if you throw the ball at a circular pole or column. Now, tiny errors in direction will make a huge difference in where the ball goes. Every approach to the earth (or other massive body) is like a ball bouncing off a pole and the uncertainty quickly becomes huge.