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565 questions in the Category: cosmology.

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1: Why does Venus rotate west to east instead of east to west.
2: I have read that Europa, one of Jupiter's moons has water on it. Why is that and do the other moons have water too? If not, why not?
3: I am doing a planet report and I am wondering how scientists know the weights of the planets. Do they calculate it?
4: Why do some planets have rings? Why do none of the inner planets have any?
5: What is the name they are thinking of naming the recently discovered planet in our solar system?
6: How much liquid is on Mars?
7: Is there any other planet like Earth in the universe (a planet that has air, water, gravity and so on)?
8: Why can't you see the stars in outer space?
9: I have heard that if you look at a solar eclipse (right at that moment)it is really dangerous. If this is true, why? Is it kind of the same idea as looking directly at the sun?
10: Does the sky ever end, because after sky there is space? But is space is still part of the sky?
11: I went to Paris a few months ago, and we went over Greenland and I spotted the aurora, and I was wondering what exactly causes this light to happen?
12: How did science determine that there was a hole in the ozone layer?
13: If there is no oxygen in space, how are there explotions with fire?
14: I know everyday we are discovering new things, but is there any limit to what we can find about what happens in space. I saw on the news that we had found a new planet, approximately how long or how much research does it actually take to get this kind of information, is their any limit to our knowledge about the planets that we come up with?
15: In what year do you think scientists will be able to see out of our galaxy with telescopes?
16: What do you think is beyond our solar system and how do you know that it exists? Also, where do think the universe ends? Do you think we will ever have enough technology to figure that out? Thank you.
17: How did the planets form?
18: When our galaxy merges with the 2 Magellanic Clouds, for how long will it take for the starburst to die down? Would space travel still be possible if we don't mind shielding ourselves better from radiation?
19: How does the universe keep getting bigger?
20: I have been reading a lot of books on how the universe started and if it is expanding or not. I would like to know if scientists know if the universe will keep on expanding forever or not. I would also like to know how scientist know if the universe will keep on expanding forever or not (if they do know). Thanks a lot.
21: There are new stars or planets being explored in our galaxy. We have discovered new galaxies, planets and solar systems. Why have we not discovered any form of life other than our own existence?
22: Is their a new planet in the galaxy?
23: One of my students and his father asked: Would a bomb explode in space? Since space is a vacuum, I was not sure what would happen.
24: Is there air in space?
25: How many planets are in our solar system?
26: Does space go on forever? If yes, does that mean that there are billions and billions of galaxies?
27: What causes the force of gravity?
28: Do wormholes really exist?
29: Where is the Darwin solar system? Is it in our galaxy? What else can you tell me about that system?
30: Is there really life on Mars?
31: How was the Universe created?
32: What are stars made of? Can we rearrange them?
33: What are some land forms found on the moon's surface?
34: Why is there life on Earth and not at other planet?
35: Why does space have thin air?
36: Why the sun does not burn itself up?
37: Are there new planets being formed in space?
38: Are there stars or planets bigger than the sun in space?
39: How do you measure the moon from the distance?
40: Why the planets show certain colors when we see them from Earth?
41: Is there life on Europa?
42: How far are stars from Earth?
43: How many stars are in the sky?
44: When will the Sun blow up? Will the planets blow up, too?
45: How far does the Universe expand?
46: Is it possible to travel through time?
47: Is it possible to travel to another universe?
48: Is there more than one universe?
49: Will we ever be able to space travel out of the Milky Way and into the Andromeda Galaxy?
50: Where do atoms come from?
51: Could there ever be life on pluto?
52: Why can we not go further in space?
53: What happens to a human being when subjected to space with no oxygen or protective suit? I have seen many explanations but I would like to know the exact reaction. Many Thanks
54: What is the cosmos?
55: If the planets are made of CO2, can there be any form of life on them?
56: What would happen if something twice the size of a black hole goes to the center of it?
57: About how big is a star?
58: How do star trails affect the Earth's rotation?
59: How does Pluto support three moons?
60: Why is there no gravity in space?
61: What are the two parts of a comet?
62: How are planets made for?
63: What would happen if you gently released a cubic foot of luke warm water into outer space? What would happen to the water? Would it stay together or separate into thousands of tiny particles? What if you did it to air?
64: What shape do you think a neutron star that does not rotate around its axis can have?
65: Do humans implode or explode in space?
66: What are the chances that we will find life on other planets in the next 100 years?
67: What would happen if you put water in outerspace?
68: I want to know why Pluto is not a planet
69: Is it true that the Big Bang was created by universes that collided?
70: How many planets have been discovered outside our solar system? Also, what are their names?
71: Do we have an infinite past and universe?
72: What are the names of the 63 moons of Jupiter?
73: What are the names of Mars's two moons?
74: How many moons are there on planet Neptune and what are their names?
75: Do we know any other life forms in other planets or galaxies?
76: What is past the Universe?
77: If the earth cracked and the molten lava seeped in to outer space would it orbit around another planet? Or would it harden under extremely low temperature?
78: has a planet or a star gone into a blackhole?
79: What result happened because of the big bang and how has it changed our galaxy forever?Also what is the big bang theory and why do scientist believe this happened and what happened during the big bang?
80: What is the life cycle of a small star and a massive star after the red giant stage? Also, do you have any interesting facts about star's life cycles?
81: Does temperature affect the received solar energy? Does it matter if it is hot or cold as long as there is the same amount of sun energy?
82: Why isn't Pluto a planet anymore?
83: Is there proof that there is CO2 and H2O on Jupiter?
84: How were planets made?
Do planets grow?
Why are the planets round like a sphere?

85: Since light is very efficient at "twisting" space and time if a suitable spacecraft were to travel into a very concentrated light beam would it experience any time dilation effects?
86: Since light is very effective at "twisting" space and time if a suitable spacecraft were to have a very concentrated, spinning, sphere of light around it, would it be able to "twist" space to travel at or faster than light, kind of like Alcubierre warp drive?
87: Is there a formula to determine how big of a "dip" the spacetime fabric will curve due to gravity given the mass/density of an object such as the earth or the sun? If so, what is it? Could it be used to determine the "flexibility" of the spacetime fabric and/or how fast it moves?
88: Can gravitational waves be "ridden" on? Can gravitational waves cause time dilation?
89: Would it be possible to enter the atmoshphere safely without the use of a heat shield? How could that be done?
90: Light, like gravity, is very efficient at bending the spacetime fabric. How powerful of a beam, or sphere of light would you need to have to bend the spacetime fabric into a 1g well? Actually, what I am really trying to say is: Is there a formula to figure out such a problem like the one above?
91: Since black holes make an infinitly deep gravitational well, is it okay to say that it isn't a "well" to some extent, but instead a "hole" in the spacetime fabric?
92: I am a retired person and I have a question. How many miles the NASA space ship has to travel to get out of Earth?
93: I would like to have a long life enough to see the smash of the galaxies. If by that time humans still exist, what will they see or feel as the first symptoms of the crash?
94: If an astronaut died in space, would he decompose? (no bacteria but what about radiation?)
95: How long does it take a rocket ship to get to the moon, and how fast will the rocket be going?
96: How many days does it take to go from Earth to Jupiter?
97: How did the asteroid belt form?
98: How many moons are there in our solar system? Are the other moons of different colors and sizes than our moon? Are there other interesting facts about the other moons? Have any other moons been visited?
99: Why is Pluto so little? Is Pluto made out of rock? Is Pluto an asteroid or a planet?
100: How was earth created and how did life begin on this planet?
101: How can the sun stay togther if its made out of gases?
102: What is a Satellite ?
103: Is Pluto a planet or a moon?
104: Why is the Earth more like a Sphere than like a Cube?
105: How did the sun got created?
106: Is there life in outer space?
107: Will astronauts ever be able to land on Mars?
108: How do scientists know how long the sun is going to survive?
109: Where did the energy for Pangaea come from?
110: If energy is destructive then how did the "big bang" make the earth?
111: I heard that in quantum physics there is something like 11 dimensions. How would you know if something is coming from a different dimension or something like that? What would be an example of something going through or coming from those different "degrees of freedom?"
112: If you take water in to space and open the container it is in will the water stay together and float?
113: Will electricity act any different in space?
114: What exactly are white holes, and how are they formed?
115: What are the astronomical predictions for the year 2009? Regarding climate changes and the orbital position of planets.
116: Do you believe that the theory of the Mayan Indians about the world coming to an end in 2010 is scientifically true? Is their any proof in the land formation or earthquake measures of a natural disaster in our future?
117: What would happen if you threw a human out into space without a space suit?
118: What are your views on pesticide use? Do you think their use is dangerous to the environment? If so, what do you suggest we do to decrease pesticide use?

I am a middle school teacher. Today I did a lesson in which students determined what their weight would be on the other planets in our solar system. We used a formula I found on the internet in another teacher's lesson Plan; the formula is:

Mass (weight on earth) x gravity (different for each planet) = weight on that planet.
The gravity chart I used looked like this:
Earth: 1
Our Moon 0.17
Venus .90
Mars 0.38
Mercury 0.38
Jupiter 2.36
Saturn 0.92
Uranus 0.89
Neptune 1.13
Pluto 0.07.

My students quickly filled in the chart and discovered how heavy they would be on Jupiter, how light they'd be on our Moon, and Pluto, and Mars and Mercury. Since they finished so quickly I asked them to find their Planetary Average Weight. We decided to throw out the Moon (not a planet) and Pluto (not a real planet anymore.) We found that every single student had an average planetary weight that was within one pound of their weight on Earth! I was in awe of this "co-incidence." I tried more weights, and the result was always the same: 8 planets, total weight on each, divided by eight ALWAYS equals Earth weight. So here are my questions:

What makes this true every time?
Is the fact that this is true the reason that Earth is just right for life?
Does our home planet have that magic gravity amount that is exactly the solar system average?
Do the planets acting together add up to the perfect gravity environment for Earth? Or does this formula have other implications?
I am very interested to know your response. Thank you very much.

120: We as humans have currently done a great bit of damage to the planet Earth. As an alternative way of disposing of garbage, would shooting large sums of trash into space be all that detrimental to the planet?
121: How do fluorescent lamps make so much light without a lot of heat?
122: If absolute zero is the coldest possible temperature, what is the hottest possible temperature?
123: We are not students or teachers from a school, just from life, we just have a question we want answered. What happens when you open a can of soda in space?
124: Is there an existence of nothingness? Can what appears to be an empty container, actually be empty? Is there any possible way to have a unit of space that contains no air? No matter? Just nothing?
125: When travelling from Earth to the moon, is there ever a time when you will experience ZERO gravity?
126: Hi! When I read or hear about asteroids, specifically about those that have impacted the earth at sometime in the past, I notice that the authors compare the force that the asteroid impacted the earth with to the strength of the atomic bomb. (Example: The asteroid that killed the dinosaurs impacted the earth with the force of several atomic bombs) Now I know to calculate the force of an object that would hit the earth (f=ma) (correct me if that is not how you calculate the force of an object that would impact earth - must I know the objects speed, etc?) but how do I compare that force to the explosion of an atomic bomb? It would be interesting to see, for example, How the impact of a 10-ton object made of a various material, and the destruction that such an object would produce,would compare to the destruction of an atomic bomb. I would assume that 1 atomic bomb would produce the kind of destruction seen in Japan during WW2? Thank you so much for your help, Happy New Year!
127: Where did stars come from and why do we have them?
128: Why is there such a small amount of Lithium in the universe? (Subsidiary questions: Does Sol have less or more than most stars? If so, why?)
129: Why does the day have 24 hours?
130: A work co11egue has asked me to ask , if an astronaut was lost in space would his body decompose?
131: Why are the planets round?
132: Hello! Thank you for your answers to my previous question. I have another question involving relativity: Imagine that somehow, one is able to produce a finite acceleration for a given amount of time, or indefinetly (I know that this would require infinite energy but please bear with me). Using this device, the person accelerates an object. Eventually, the object approaches the speed of light. Given my current knowledge, an outside observer seeing that object would notice that it is constantly approaching the speed of light, but (according to the observer) it would take an infinite amount of time for the object to reach, and pass, the speed of light. Is this correct, why is this? However, the object that is accelerating would notice that it would take a finite amount of time (according to it) to pass the speed of light. I know this is similar to the case in which an object is observed passing the event horizon of a black hole. (an outside observer would have to wait an infinity to see the infalling object pass the event horizon, but the infalling object would pass the horizon in a finite amount of time) Now for my second question: Can the accelerating object (or the object that passes the event horizon) still be considered as traveling back in time (when it passes the speed of light according to it, or when it passes the event horizon according to it)? Why or why not? Thank you for your help.
133: Hello! I have recently tried to calculate the gravity of a black hole at the event horizon. In other words, I want to calculate the surface gravity of an object if the escape velocity to leave that object is the speed of light. But I dont think I did the math right. I believe that the required gravity is less than infinity because there is only infinite gravity at the singularity. How can I determine the gravity of an object when the escape velocity is the speed of light (or more)? Please show how to calculate it. Thank you so much for your help!
134: What keeps earth from collapsing in on itself like at the end of a star's life? Is it not big enough or what?
135: I want to know why we always look at the same face of the moon. Can you explain to me the reason?
136: What would happen if you spilled a glass of water out in space?
137: How different are the atmospheres of Venus, Earth, and Mars? Can you tell me the characteristics that make them different? Has any of these three planets a very different atmosphere from the other two?
138: Why doesn't the earth sink?
139: Can absolute zero stop time?
140: Is there another way to stop time than traveling at light speed? I learned that mass can't go at light speed unless we have infinite energy (which we don't). If there are other ways of stopping time, won't it be so much easier?
141: Before the Big Bang, was the universe matter or energy?
142: How do photons travel so fast? Is there a way to stop them?
143: If there is no time before the Big Bang, then how can the Big Bang happen? Was not everything stopped?
144: Why the Bode Law fails to predict Neptunes orbit?
145: Do the planets grow in size?
146: Since the moon circles the earth once a month why is there not some type of eclipse every month?
147: If a fragment from an asteroid falls to Earth and a static electric charge is built up as the fragment falls, does it generate a magnetic field? If so, why does it happen?
148: Are there any plans to try to move the moon back to a closer orbit with the earth, through some kind of gravity manipulation, or other ideas?
149: Because of certain chemicals (ethyl formate) found in a big dust cloud in the middle of our galaxy, Saggitarius B2, is it true that the Milky Way would technically smell like rum and taste like raspberries?
150: A video said that before the Big Bang, the universe was the size of an atom. Another video said that before the Big Bang, there was no space. If so, where is this atom-sized universe? It is got to be so where?
151: How do we know that the earth revolves around the sun? Is the sun in a fixed position? The sun is seen crossing the sky, but so is the moon. Isn't the center of anything relative to your position?
152: Do you believe the big bang will reverse itself, as a few people have predicted, and suck back in to its "origin"?
153: What happens to light in a black hole? Is there an end to a black hole?
154: I have heard of parallel universes, but I do not understand them. Can you explain these, and can you tell me if there is such a thing?
155: How can you tell how many miles or light years away something is if you can't go there? What sorts of instruments do you use?
156: What concrete evidence do scientists actually have that we evolved from monkeys and that the "big bang" actually happened?
157: How does the gravity of black holes exist without any mass?
158: If you throw something in a black hole, where does it go and what happens to it?
159: What makes a supernova? What types of energy does a supernova give out when it explodes?How far does the explosion of the supernova go? How common are supernovas?
160: How much longer will the world exist according to scientists?
161: I found this web site called Universe, The Big Bang. It said that the universe was created 15 billion years ago. Is that true? And how would someone know if we werent alive? Did the universe begin because of the big bang? The last question is, who discovered the universe?
162: Are all chemicals harmful to future generations? Do bug sprays harm babies? What exactly causes air pollution? What type of diseases does pollution cause for humans? If pollutions was to enter a black hole what would happen?
163: Could life survive on a Asteroid? On Earth there are six characteristics of life. In the search for alien life forms are the characteristics of life the same?
164: Does space ever end?
165: Is there a fourth dimension?
166: Why is space black?
167: If there is an end to the universe, what's beyond it?
168: How many solar systems could be in a galaxy if there a billions of stars in a galaxy?
169: What created the Big Bang?
170: How are stars formed?
171: How did people discover the planets?
172: We currently know that Dark Matter is matter that is in outer space and occupies a great deal of matter in the Universe. It could be many things such as planets, dormant stars, or black holes, but we are seeking the truth... What is Dark Matter? What do we need to know about Dark Matter that we dont? Is there any significant information about how it differs from the matter on earth?
173: I am currently participating in a project where I have to design a space settlement. I would like some data on the materials and the processes being developed/studied here. If you have any such information, could you help me?
174: In regards to extraterrestrial life, I wonder about their "rate of life". I mean, could what we call a second be a year for their species. So, a message from us like "Hello" would be a year- long "HHHHHHHHHH...eeeeeeeeee...lllllllllllllllll lll...oooooooooo." If our thought processes are at two very different rates, then communication would seem impossible. OR, is there one rate of life in all the universe? It seems that this would have to be the case for any contact to occur since the probability of another species' "rate of life" being close to ours appears to be zero. Do you think our rate of life is connected to the speed of light. So, for example, an alien species with a rate of life one hundred times ours would see light travelling one hundred times slower? (or faster?)
175: As a scientist, how would you explain how the Earth was created after the Big Bang occurred? Where did animals, plants the human race come from?
176: If the sun were to explode, what is the probability that human life forms would survive? Is there a possibility of a "Counter Earth."
177: Could a black hole be destroyed if the amount of mass that was sucked in was bigger or about the size of Jupiter?What is a worm hole? How are they formed? Could you enter one, and what would object inside or outside the worm hole look like? What would happen if two black holes were side by side?
178: Why are red stars cooler than white stars? I thought red things were hot.
179: I'm interested in the solar system. I want to know about the things you are learning. I want to know about the special interests you have to share with me and what you are specifically learning about.
180: Measuring light years:How is the speed of light actually determined? How could you measure something that's speed is inconceivable to us? If we went somewhere else...say a star and watched the light from the Earth reach us, would it be like watching a movie?
181: What would happen to me if I went through a black hole? Would I end up in a different universe?
182: Do planets ever stop growing?
183: Why do we orbit the sun but it doesn't orbit anything?
184: Does the solar system ever end and if so how ? Is there a wall or does it just go on forever?
185: How do we get the satellites to other planets like Jupiter so fast if it takes a regular rocket 5 years to get there?
186: How do we know how stuff really is out there if it's too far out to explore and would take years to get to?
187: How do you know how many galaxies there are in the universe?
188: How did the carbon get in the universe to form the nebulas?
189: A student read that the star Arcturus was moving differently than other stars (perhaps in a different direction?). Do you have any information on this?
190: Please answer our question about space. The sun is out in space. Around the earth it gets very cold and the air around us is cold. Out in space is it cold warm or very hot?
191: Can a moon have a moon? Is there any such thing in our solar system or evidence of it in the past?
192: How are Solar Flares are related to the Magnetic Poles on Earth? How they work? I can't find that answer in any of the books I looked through.
193: If there was water on Mars, would we be able to live on it?
194: Why isnt there any oxygen in the universe and the planets around us?
195: If we send all of our nuclear weaponry at Jupiter could we ignite it to become a star?
196: Have there been documented cases where a person has received radio waves on the metal in their mouth or metal plates in their head? (Or is it even possible for some to receive radio waves in the metal in their head?)
197: How can you calculate your age on the Sun?
198: Imagine that you make contact with an extraterrestrial intelligence. What units would you use to communicate ideas about how our planet or solar system operates? It seems that the units of time, distance, and mass which we use are based on features of our own system and wouldn't necessarily make sense to an intelligence from somewhere else (e.g. Second, Hour, Day, Year, Lightyear, AU, Kilogram, Meter, are all arbitrary or based on the location or movement of the Earth). What are units which anyone from our universe (but not necessarily our planet) would be able to recognize?
199: Do black holes really exist? If yes, why we have not found them moving around neighboring galaxies?
200: Can you hear a space ship in space or a super nova?
201: How would I calculate the magnitude and direction of acceleration of a galaxy moving towards another galaxy? The only values I know are that both galaxies mass = 1.42 x 1042 kg.

202: If we take water to space, how is the water density affected?
203: How does the lunar orbit compare to a circular path?
204: How do other planets affect Earth's gravitational pull?
205: How was the moon created?
206: Can a black hole be created by the Earth's pollution and our radiation?
207: Why isn't Venus livable if it's just like Earth?
208: What does it mean to have four tides?
209: Does the sun rotate?
210: In Social Studies, we are studying landforms but our textbook doesn't tell us anything about volcanoes or canyons. Can you tell us more about these types of landforms?
211: Why does the moon have so many craters?
212: What would happen if the world rotated in the opposite direction than it already does?
213: How many moons are on the planets?
214: Is there bacteria life on Mars?
215: Is there a possibility that there are some living things outside the earth?
216: Does your nose run in space?
217: If we were to communicate with an astronaut on space, would there be a delay? If so, how late would that communication be? And how would they communicate with us?
218: How does a rocket travel from Earth to the moon?
219: How does the moon control the tides? Can you put it into a way that is easy to understand?
220: Is Europa colder or hotter than Earth?
221: Why has x-ray been detected to pass through a black hole?
222: Will the solar system end soon?
223: How does heat transfer?
224: How did the earth layers form, and how did the dinosaurs become extinct?
225: I'm doing my science fair project on black holes. I learned that inside a black hole there is a very strong gravitational pull. My hypothesis is that around the black hole there might be a spinning force (similar to tornadoes)as the galaxy rotates around it. This spinning force should draw objects toward the black hole. Am I on the right track? Do you have any suggestions about how to test my hypothesis?
226: What is a black hole?
227: How does the moon cause high tides?
228: How many moons does Saturn have?
229: Why do you weigh less on the moon than on earth?
230: Why hydrogen have only one atomic number?
231: Why does the ocean get bigger gravitational pull of the moon? Why low and high tides occur throughout a day?
232: Why does the moon have phases?
233: Why are planets in the shape of a sphere?
234: How are galaxies made? I know we live in the Milkey Way.
235: Why is there no oxygen in space?
236: Is there any chance of life up in space?
237: Why is Jupiter's red spot red and what keeps it from dying out?
238: Why do we float in space?
239: Why do have to wear a helmet in space?
240: Did Mars ever have life on it and was there water once?
241: How do you know for sure that space never ends?
242: Why can't we see other stars or their solar systems/and how far are we from the other solar systems?
243: Have the planets ever lined up? If they have, what was the year?
244: When was Pluto considered a dwarf planet?
245: Is the sun the hottest star in the Universe?
246: What is a nebula and is it the first part of the sun's life cycle?
247: Why does Saturn have a ring that floats?
248: Why does the earth have to spin?
249: About how many stars are in space?
250: What are Saturn's rings made of?
251: What god was Pluto named from?
252: How does the moon control the oceans tides?
253: What is your frame of reference for what to measure for elevation from on the moon? How does a compass perform in deep space? What does it point to? Best Regards. Also, you guys should watch adventure time. It is majestic.
254: How are galaxies made? I know we live in the Milky Way.
255: How far in distanc is space form earth?
256: What is the biggest star that scientists know?
257: Does the moon out off heat?
258: How do all the planets seem to be floating and why they don't fall in to space?
259: What will happen if a human would go through a black hole, what would I see?
260: How did the Solar System started and when?
261: How come our solar system does not go off to space?
262: Why is Venus hotter than Mercury if Mercury is closer to the sun?
263: Why are most planets and stars spherical?
264: How are planets made?
265: When was Earth made?
266: If the universe is expanding, how is that galaxies can collide?
267: Is it possible for any life to exist on Saturn?
268: Does the sun grow or does it stay how it is right know?
269: When you go to space, can you get out hydrogen from the sun? How do you get hydrogen on earth?
270: How does the asteroid belt form?
271: Where did the planets get their names?
272: Why is the sun so bright and hot?What instruments do scientists use to study the sun?How big can a solar flare get?
273: Why is the sun so bright and hot?
274: How does a galaxy form?
275: How earth is different from the other planets?
276: Why do planets have different layers?
277: How is Mercury different from the other inner planets?
278: How many stars are in the galaxy? Is it true that if you go into a black hole, you can still come out?
279: How fast does the space rocket go, so it can get through our atmosphere?
280: I want to ask about the theory of the multiverse system. If the science community feels it exists, how ? If not, what could be the possible boundary of our known universe? and what is the relationship between a multiverse system and quantum mechanics, with emphasis on linear and 3D time frame, random events, etc?
281: Can we survive on the sun?
282: We know that the sun is not the biggest star, but is it the hottest star?-Thanks.
283: Why do we have more gravity in our earth than in the moon?
284: Why moon takes 28 days to revolve and rotate around the earth?
285: Why is the sun made up of plasma and nitrogen?
286: Why do the stars orbit each other?
287: Is Pluto gas or rock?
288: I understand that a quantum description of gravity would necessitate the transmission of gravity through a mediating particle, the graviton. This makes me wonder about black holes. A black hole would have to be emitting gravitons all the time. It seems to me that an isolated black hole -- even ignoring Hawking radiation -- would have to be losing energy just through the emission of gravitons and thus lose mass. Is this a correct extrapolation? Thank you.
289: How are ocean tides formed under the influence of the moon and the sun, and the influence of the revolution of the earth?
290: Which stars are cooler red or blue?
291: Can humans live on Mars?
292: How the earth and other planets are circling around the sun, and why they are not going away from it?
293: Who found out that there were planets?
294: How was space discovered?
295: Why do planets have different colors?
296: Why is the sun hot?
297: How does a rocket travel from Earth to the moon?
298: How did the elements came to existence?
299: How dose the water get attracted to the moon?
300: Light has many sources. The greatest is the sun. Are scientists using other light from other stars to produce energy?
301: Why and how do planets rotate and revolute?
302: I have tried to calculate the moon's gravity at 100,000 km distance from its surface by using the inverse square law, but I get confusing results. Please help me.
303: What will happen to the landmasses after approximately 200 million years ?
304: Does a rocket ship have to orbit the earth to get to the moon?
305: Will black hole travel like other celestial bodies. Is there a chance of our earth and solar system being attracted by a Black hole.
306: Can you explain string theory for me? Thank you.
307: What are the most influential factors of water tides?
308: How do we measure the radius of other planets? Thanks.
309: Could any of the "gas giants" (or other planets) in our solar system ever become Sun's? Let's say the Sun burns out, if Earth has somehow been saved from certain demise, could a "gas giant" be ignited as if it were a spare lightbulb? If so, would our solar system change directions and start to rotate around that planet?
310: Which gases are there on Mars?
311: How slow does the earth spin?
312: I have searched on multiple websites for the answers to these questions, but I can't find them. What do scientists say the density of the earth is? How do scientists actually measure the earth's density?
313: How does a hurricane form?
314: How does nuclear fusion fuels our sun?
315: Does gravity prevent Earth from flying away from the Sun OR flying into the Sun? Please explain answer. Thank you.
316: How does the earth movement around the sun affect the stars patterns we seen in the sky?
317: Does the solar systems form in the center?
318: Is it true that the earth's core is made of metals iron and nickel, and that the earth's crust is made of mostly the elements of silicon and oxygen? Why?
319: How is it possible to breathe in zero gravity?
320: How often do astronauts die out in space? And if they do what causes them to die? And how long can you live in space and your body is still fully functional?
321: Hi,
I was reading an article on NASA website, talking about the earth speed slowing down; hence days are getting shorter
here is the article

My understanding /conclusion is that eventually and according to laws of Physics, Earth at some point will stop spinning for a moment in time, and then start spinning clockwise instead of counter-clockwise. Is this possible? Thank you.

322: Will a human body explode in space if sent without helmet in space? According to me, internal pressure will be very high and there will be nothing to balance it so it must explode. If no, then why?
323: Does the cycles of the moon affect water evaporation?
324: How far away is Earth from Saturn?
325: Why does Jupiter have a red spot?
326: My Question is: How much oxygen will land based microorganisms convert in a Mars like atmosphere? I need help getting the tools for this experiment. Is there somebody who could help me?
327: If you got cut out in space, what color would your blood bleed out as?
328: How long would it take to reach the solar system from earth?
329: Why are there moon phases?
330: Are stars hot or cold?
331: Does Pluto have an atmosphere?
332: What would you need to survive on Venus?
333: We were looking at the composition of elements in the universe and saw that it is 75% Hydrogen, 23% Helium, 1% Oxygen, and 1% everything else. Why is there so much Oxygen in the universe compared to the other elements?
334: How far is the very first satellite launched into space?
335: If the moon draws the ocean towards it and causes high tides, why is there a low tide when I can see the moon overhead?
336: Imagine two astronauts on a rotating space station. The station is rotating about its axis at some rate R clockwise as seen from the perspective of an outside observer (or an observer at the axis). On the station there are two astronauts. One is standing in place and rotating clockwise at the same rate R as the station from the perspective of the outside observer. He experiences some centrifugal force F away from the axis of rotation. The second astronaut, doing some exercise, is running counter-clockwise, at the same rate the station is rotating in the clockwise direction (lets call his rate -R). As seen from the perspective of the outside observer, it seems like the astronaut is jogging in place. Question: Does the second astronaut, rotating at the same rate as the space station but in the opposite direction, still experience the centrifugal force caused by the rotation of the space station?
337: How many galaxies are there in the Universe?
338: Why is the atmosphere of Venus more friendly to plants than humans?
339: Why is air pressure in outer space less than on earth?
340: What is the difference between a black hole and a worm hole?
341: I understand how gravity is the curvature of spacetime, but what quality of spacetime allows it to move back to exactly how it was before a body of some mass influenced it? What balance keeps spacetime constantly "smooth"?
342: How many solar systems are in the milky way galaxy?
343: Why do scientists believe that the earth developed in layers?
344: Is Pluto a gas or solid planet?
345: I recently read the Planiverse. Would a 2D dimensional universe be possible? And would there be any way for us to see/visit it?
346: According to Stephen Hawking, the laws of Physics allow the Big Bang to happen, because the random motion of subatomic particles generated energy to create an explosion. How exactly did these subatomic particles appear. If the Big Bang was caused by the random motion of such small particles, then what created such subatomic particles in the first place, and what came before them. Also, how exactly did the Big Bang generate forces like gravity to come about in the universe?
347: Is there any real life on Mars?
348: What are planets made of?
349: If we know of sun based systems throughout space, is it possible to have a system based on massive planets or other bodies (excluding black holes,) or would the mass be too great that it collapses in on itself?
350: If the rest of the universe had earth's gravity, would we be floating? And if so, how high would we float?
351: How does the Earth heat up?
352: Is there more than one universe?
353: Is the world ever going to end?
354: Why does the far side of the moon never face Earth?
355: Where have humans explored in space, and what are the details to what they have found? Thank you very much!
356: Outside, my mother and I were watching the blood moon of April 15, 2014. The moon is (looks) like it is behind a tree. When it came from behind the clouds, it looked like it lifted. How is this? Is it true? How often is it? Why?
357: If you let your air out in space will there be a pocket of air in space?
358: If a comet passes too close to Earth, what might happen?
359: Why some planets have rings and others do not?
360: My friend refuses to believe that the earth rotates around the sun because all he believes in is religion , he refuses to believe any logic. What is the easiest way to prove to him that the earth rotates around the sun and not the other way around?
361: We estimate the temperature of a star from its color. But what if the star is moving away from us at a constant rate? Then, its light would be red shifted. So, how will we know its temperature?
362: Does Pluto have any moons?
363: Can you please explain holographic and anthropic principles with easy examples?
364: How does the Sun have a gravitational force? Doesn't gravity depend on an atmosphere?
365: I know this question had often been asked but I don't get to understand it. What do mean when we say that space is expanding? I think that space is not a physical entity that can expand. Space is just (apparently) "nothingness". Please solve my confusion.
366: Can you tell me why the atmosphere is important?
367: What force makes earth stay on its orbit?
368: Why is Mars a red planet?
369: Is there any particle faster than light? if so, what is it? Is neutrino faster than light?
370: Why is an atom electrically neutral?
371: Why the sun does not fall on the earth?
372: What is the size of the Sun?
373: Where does carbon dioxide come from?
374: How are stars aligned?
375: Can you explain to me why is a ball on a string like a planet in its orbit?
376: Is Earth's core as hot as the surface of the sun?
377: What would happen if a comet hits Earth?
378: I was wondering if there are billions of stars in the galaxy and we are inside of it, why do we see dark nights? Wouldn't the space always be bright? Thanks
379: What is the Shape of Our Universe, and where is it situated? I would also like to know what is there outside the Universe?
380: Why does tides occur on seas and oceans but not on ponds and lakes?
381: What makes a planet different from a star?
382: How far away are stars?
383: How can there be gravitational pull in space but no gravity?
384: There is an article on your site about the gravitational pull of the planets upon each other. My question is what happens when the earth passes through the gravitational field between the sun and another big planet such as Jupiter or Saturn. So there would be some gravity between the earth and Jupiter, but there would also be gravity between the sun and Jupiter and the earth would be passing through this field. Can this be measured? What happens? Casey the Curious.
385: Does our solar system have a name? All we say is "sun system".
386: I have children in Grades P-2. One of my young students asked me if the earth is round because of gravity, how come the other planets are round that have no gravity - I tried to explain the mass and gases idea to them and they looked at me as if I was from another planet. How do I explain the reasons planets are round in simple terms they will understand. Please keep in mind these are 4-6 years old children.
387: How was our Earth made?
388: What planets have Oxygen in their atmospheres other than Earth?
389: How long does it take for a rocket to get into space?
390: Why does the ocean seem to rise at night time?
391: Is our sun really a star?
392: What instrument did you use to gather information about stars?
393: Are there really Aliens from outer space?
394: Would a black hole be able to eat an object many times bigger than its own mass? If not, what would the reaction be?
395: What would the reaction be if a black hole crossed paths with another black hole of the same size?
396: Why does the moon turn red at times? And why is the sky blue? Can the sky turn into another color, and if so what color?
397: What would happen to the moon if the earth is gone? Will the moon find another planet to circle around? If yes, which would be that planet? Would the moon go on in the same circle without a planet? Will the moon be gone before us or will be death with us? What will happen?
398: How does the moon control the tides?
399: How Silicon came about on Earth?
400: How does space never end?
401: Why does the Earth rotate on an axis?
402: I am in Big History at Grayslake North high school in Illinois. I am doing a project on how Silicon came about on Earth. I came upon your answer on to why that is. I want to use your answer in my project but I need to cite my work so I don't plagiarizer. When I used easybib they were not able to give me a publisher of a electronically published date. I was just wondering on if you can give me a name and a date so i will be able to use it in my project. If not that is fine, I can find a different article. Thank you for your time. Have a nice day!
403: Why the ring of Saturn is visible to us and the other outer planets like Uranus ring's is invisible to us?
404: What would happen if the sun exploded?
405: Are there stars bigger than the sun?
406: Do all the planets take the same time to revolve around the sun?
407: Without any example, could you tell me how do scientists measure gravity?
408: Is there air on any other galaxy?
409: How did Apollo 2 get off the moon? Doesn't rocket fuel require oxygen to work?
410: Tides are formed by the gravitational pull of moon. How does the water get attracted by the moon even though the gravitational pull of earth is greater than that of the moon?
411: Can we see Saturn from Earth with naked eye?
412: Do all planets rotate from left to right?
413: How was the sun formed?
414: What is the safest place to be if a supernova occurs?
415: Is Venus hotter than Mercury because it is full of carbon dioxide or because it does not have an atmosphere?
416: Why can't humans go to Jupiter, and why isn't it safe to go there?
417: Scientists claim to be true that GRAVITY IS THE WEAKEST OF ALL THE 4 FUNDAMENTAL FORCES OF NATURE! Now here's my question:
Being the weakest of all the 4 fundamental forces of nature, why is it that the gravity of black holes can bend even space, time and light? If it is true that gravity is the weakest force, then the black holes are violating the laws of classical mechanics! Is it correct to say that gravity is the weakest force?

418: Why the universe has not end and why is it too big?
419: How the heat of sun come in earth when there is no medium?
420: Does the sun have an explosion every day?
421: How many stars are there?
422: How big is the sun? How big is the earth? How big is Jupiter? Can you compare them?
423: Hello, I am in 7th grade and was in Science class while thinking, Man to Mars communication. My question would be, while Man is on Mars will they be able to communicate back to family and friends? I know they will be able to back to the Space Station but I was curious about the family and friends part. If so, will this be freely chosen times to talk or schedule time? Thanks,
424: How does a moon rock look like?
425: I'm doing a project for school. I was wondering if you could answer a few questions I have about stars. Why are there stars out at night? Do we use them as like night lights? Where do they go during the day? If we didn't have stars, would it change our daily life?
426: What would happen if the sun and moon collided?
427: Are stars useful why/why not?
428: Is there some other planet with an atmosphere that we can breathe?
429: How fast do meteors travel? How far is Mars from Earth, and how fast can we get there?
430: Are scientists working on traveling to the sun? Is it possible to visit other planets with different kinds of space suits?
431: What will happen with the hot water in the sun when it evaporates?
432: What is the closest planet to Saturn and how far away is it?
433: Why isn't Pluto a planet anymore for a fact I am asking?
434: Why can't we feel the Earth move?
435: Why don't asteroids get pulled into Earth's gravitational pole?
436: How long does it take for Mercury to make one full orbit?
437: How long has gravity been on earth?
438: Why don't asteroids get pulled into Earth's gravity?
439: What made Earth's atmosphere? Can it make more atmospheres?
440: Does space have a floor or is it just like an endless pit? If it does have a floor then, what is it?
441: How many asteroids are in the Solar System?
442: Theoretically asking, what would happen if the sun were just removed? Not explode, just completely vanish. Would each planet continue a tangential orbit and become like meteors or would they change their orbits to Jupiter, knowing it has great mass. My physics class is presently talking about this sort of subject and it interest me quite a bit.
443: Why is there a storm in Jupiter?
444: How many volcanoes are in Mercury?
445: It seems that the universe was created by a big perfect explosion, it is also expanding in harmony to the point that it has created galaxies where billions of stars were formed. It also seems that stars created their own planets becoming solar systems. It seems that our solar system has been shaped with the right conditions in order for earth to become a green house and support life in many ways. Our plants, animals and us as a species are structured with DNA coding. Our universe is full of constants such as gravity, and speed. My question based on my observation is the following: Is the universe a computer program due to the fact that there are not coincidences other than cause and effect?
446: Including its rings which planet is bigger Jupiter or Saturn?
447: Why does Earth have a moon and not Venus or Mars? And why Saturn has rings and not the inner planets?
448: Why we cannot go to different galaxies?
449: What is the hottest star? Is there a hottest star in the universe or when a new one is born will it become the hottest star?
450: Why are there only 8 planets in the solar system?
451: What would happen if the earth did not have the sun....or the moon?
452: Why isn't Pluto a planet? I think that it was a star but people think that it was a planet and that you guys saw a real planet, is it true or no? I am not in school summer break.
453: NASA and the whole world is basically looking for other life on other planets within our solar system. Or, more specifically, "life as we know it." What is life as we know it? What are we looking for, and what would be defined as life that we don't know?
454: How the orbit of earth around the sun is elliptical and not circular? Thank you very much.
455: How is Pluto a star is it because it is to far away?
456: When you look at the sun, is their a moment when you cant see at all?
457: Does anything else other than the moon control the tides? Does a certain life force live that controls the tides but makes it seem like the moon? Can another life force control the tides?
458: What is the size of a star?? And why a star is looking so little & blinking?
459: Why does the sun have sunspots even doe the sun is the sun?
460: I've been researching, and Venus seems AWFUL. Is there anything good About Venus?
461: As a scene shown in interstellar movie, there are two different time dilation in two different planet having different gravity. Is that true? And if it is true, is its due to gravity or location and speed or orbiting of that planet? Thanks.
462: When is that space dust and gases become a star?
463: Was Jupiter ever a solid planet?
464: Can a black hole die?
465: How are black holes made?
466: Does Jupiter have a solid core?
467: What happens when the sun dies?
468: How earth formed ?
469: If the supplies don't make it to Mars what would happen if the people get there and the supplies don't make it? What would the people do and why is it a one way trip?
470: How deadly is Mars?
471: Is it a good idea to send people to Mars?
472: Why would people want to live on Mars?
473: Why don't comets hit Earth?
474: Where is the sun located in the Solar System?
475: Of the four main elements that make up life on earth, are they present on other planets?
476: If a solid has a 180g on the moon? Would it have the same weight on Earth as on the moon?
477: How does the force of gravity exerted by the Sun on Jupiter compare to the force of gravity exerted by Jupiter on the Sun?
478: I want to know about NASA. Can you tell me about it?
479: Does one of the gas giants have any destroyed moons?
480: If space is constantly expanding, what exists beyond its boundaries? What is space expanding into?
481: What makes the moon uninhabitable?
482: Are there new planets out there but people don't discover them? I just wonder whats out there.
483: If the sun is a star, why doesn't it explode?
484: Why is Pluto so small?
485: What is the Milky Way?
486: If a cloud of hydrogen and helium were squeezed together until it heated to a temperature of about 10 million °C, what would happened?
487: What temperature is the earth's crust?
488: I heard that when particles are accelerated to light speed (300000 km/h), then collide, it opens a warp in spacetime, like a miniature black hole. Is this true? Also, could we use this information to tell what is in a black hole?
489: If the moon has so little gravity how does it have such a force on our tides?
490: Are tachyons real?
491: Where did the moon come from?
492: Why does craters disappear on gaseous planets?
493: How would you get air in space?
494: What would happen if the universe exploded?
495: I have recently found a bit of information on the Horse head Nebula. I was wondering if you know of any credible sources I could use.
496: How are solar flares related to the magnetic plea on Earth? How do they work?
497: Why is the atmosphere of Venus more friendly to plant than humans?
498: Why should we explore Saturn?
499: Why does it happen an eclipse between the moon and the sun?
500: Why do astronomers use astronomical units to measure distances in our solar system?
501: Which planet is lighter, Saturn or Neptune?
502: Is every star a planet?
503: Do we have to worry? Is the sun going to explode before we die?
504: Has the Mars Rover find life on Mars?
505: Is Pluto made of gas or a solid?
506: Can humans live on the sun why or why not?
507: Are black holes an illusion?
508: What filled in the impact craters on the moon and mercury?
509: If Earth were to lose its magnetic field, how fast would the atmosphere leak into space? Will it take days, months, years for the gasses to be blown away by the solar winds?
510: How did the sun form?
511: Why is the sun growing?
512: How long does it take to get to Titan from Earth in a rocket that's going 2,500 miles per hour?
513: Does the sun change temperature throughout the day? If this happens, what is the rate of change per hour/day?
514: Hello, I was reading the Q&A about how gold was formed. It seems there are "theories" of gold being formed in a supernova explosion. Is this theory or fact?
515: After the Big Bang, they say the Universe expanded (inflation) and cooled. Isn't heat the energy that makes molecules move faster? How can a universe "cool" if it's not made up of atoms? Can energy "cool"? As the universe cooled, did energy convert into more Hydrogen gas or did all the Hydrogen in the Universe get created from the start? When the energy of the Big Bang "cooled", did it coalesce into matter?
516: Why was the Big Bang?
517: About how much oxygen will be needed as a fuel in order to get to Jupiter or Pluto ?
518: How was the earth created?
519: Does the size of the moon effect how big the ocean waves are?
520: How do stars ignite?
521: Is there any life outside our solar system? How will we know? When will we be able to know?
522: Is the universe endless? And if it isn't how big is it and is it just a big wall or like a planet?
523: Does science have an estimate on the size of Outer Space, and if so how far?
524: Why does the gravity lessen in space? Is it because we are going away from the earth? Then why don't we just float away on the earth? Is it because of the atmosphere protecting us? If so, What if the Atmosphere didn't exist?
525: What will happen to the Earth in about a million years?
526: Why does the moon change shapes?
527: How does the moon affect the tide?
528: How was everything on Earth created form two asteroids "hitting" each other?
529: Does space ever end?
530: If you brought a moon rock home to earth, and took it out of it's vacuum container, would it explode or implode?
531: What keeps earth from falling into the sun?
532: What factors keep a planet in orbit around the sun?
533: Are there other planets in space, other than the ones we know?
534: Can matter be created or destroyed when a chemical change occurs?
535: What are the three reasons Pluto is no longer considered a planet?
536: Does the moon rotates South to North or North to South?
537: If the universe is in a constant quest to reach an equilibrium, and lets say it finally does reach this point, what will happen?
538: Is there really two suns being discovered around planet Earth? If so where are they siting? Please send pics or video links. Thank you!
539: Are the ocean tides and waves connected to the planets and stars?
540: If the sun ever blow up, will people still be on Earth or will it be the end of the world?
541: If you deliberately drilled a huge hole at the North Pole, and allowed all the earth's magma to spill out, as the earth tilted, could the weight shift, cause the earth to "flip" upside down, thus causing a reversal? Sounds plausible to me.
542: Can the moon turn full between rising and setting?
543: In space gravitational force acts, then why we can not write with pencil /pen in space(outside the earths orbit)?
544: What is the average radius of the sun, in meters?
545: What is the hottest star within 20 light years of Earth?
546: Is there comets or asteroids we don't know about that could be on a collision course with Earth? If so do we have a plan to divert them?
547: Can a spaceship land on Jupiter?
548: How many days (not years) would it take to get to Jupiter?
549: Where does the wind come from on Mars?
550: Will the stars appear very bright in new moon day? Or full moon day?
551: What is the ISS?
552: Could life survive in/on an asteroid?
553: I've heard that the moon pulls at the water on Earth, creating waves. How does it do that and why doesn't it effect smaller water sources such as puddles/streams?
554: How do things explode?
555: How wide is Mars?
556: Is there any planet in the universe that is bigger than the sun?
557: Did the Apollo spacecraft fly in a straight line before entering the moon's orbit? I was told the spacecraft kind of travels like a sailboat tacking through the water. Sometimes the Apollo would be on course then off course. Actually I was explained the Apollo traveled only "on course" 2% of the time.
558: Is it possible to make a black hole stretch and if so how?
559: Why are there stars that are bigger the the sun?
560: If we would be able to cool Venus down and make it habitable, how would we benefit from it?
561: Does the sun explode?
562: How does the sun's gravity affect the other planet's orbit?
563: What would happen if there was no sun in the universe, not even stars?
564: How far is the sun?
565: Why does big planets have rings and small ones don't?
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