Quickie Questions - Last 100 Questions
| Date Answered | Questioner (age, location) | Question | Answer |
|---|---|---|---|
| May 4, 2011 | rin(romania) | When uranium atoms split the neutrons clashing eachother release the energy to make the atomic bomb, but how come so much energy from such a small piece of uranium? | This is a perfect example of Einstein's equation E = m•c2. Although the excess mass m of the un-split uranium is small, the factor c is so large that the energy release E is also large. The physical reason is that uranium is less stable than what it splits into. |
| April 9, 2011 | Sydnee(Australia) | I need to know how and why salt water boils faster than tapwater. thanks | It takes more time for salt water to start boiling because it boils at a higher temperature than pure water. The time to completely boil the water to steam is about the same. The dissolved salt reduces the water vapor pressure P, because salt has a P of zero. |
| March 20, 2011 | keon(canada) | how many much energy in watts do you produce per foot step? | An adult human metabolism burns about 100 watts = 100 joules/sec. About 22% of that power is converted into mechanical energy, so lets say roughly 20 watts are produced while walking. A foot step takes maybe 0.5 sec of time. So I think the answer is 10 joules per foot step. |
| March 20, 2011 | frank | I don't know what the "2012 riddle" is. I read that some people believe there will be a global transformation or catastrophe in 2012. Like many predictions, that one may or may not be true, but I find no scientific basis for believing it. Science is concerned with predictions that can be tested by experiment or observation. | |
| March 20, 2011 | robert(oklahoma/us) | Hello. Please help clarify something. A friend of mine recently told me that the brain does not cause or create thoughts, it merely processes them. According to her, the heart has neurons just like the brain, so the heart actually can think. She also asserted that there is growing evidence from cellular memory and | Recalling my "Philosophy of mind" course at college, and after just a little catching-up reading, I feel safe saying that too little is known scientifically about thinking to distinguish between "creating" and "processing" thought. It seems obvious that the brain does both, so the onus on your friend is to explain what creates thought, if not the brain? Also, does merely having neurons imply a heart is thinking? A nematode worm has all its 302 neurons mapped by science, but does the worm think? |
| March 6, 2011 | Gavin(Memphis TN) | How big is space? | There are two parts to the answer to the question "How big is space?". Part one is to consider how old are the most distant objects we can see, which is about 14 billion years. Part two is to consider that during that time, the universe was growing. After a little mathematics you calculate a size of 47 billion light years. |
| February 22, 2011 | George(New York) | All substances in the universe moving away from each other. But Is there no end to it? Could you put your answer Astronomy Anomalies ? | See The Future of the Universe. If the motion of substances away from each other is fast enough, it will overcome gravity and never end (like a rocket exceeding escape velocity from the Earth). Otherwise, in the far distant future gravity will overcome motion and everything will return to one small volume again, a Big Crunch to reverse the Big Bang. |
| February 21, 2011 | Thomas | In the segment "What is life" all the characteristics given can also be said about fire. Does that mean fire is alive? 1) Fire takes in energy as it burns (metabolize). 2) Fire gets rid of waste by moving on to another source. 3) Fire spreads and grows. 4) Fire responds to it's environment. 5) Fire reproduces. 6) Fire can change over time in response to it's environment e.g. change in wind direction can alter the course of fire. | This is a good question, and is often raised in response to the definition of "life". In the article What is Life?, the last 3 characteristics refer to "traits" that contain significant information and complexity (e.g., as encoded in DNA), whereas the physics of fire is relatively simple. |
| February 21, 2011 | Daniel(United States) | I know the tilt of the earth causes earth's seasons. Regardless of that, what was the exact distance of the earth from the sun in June and December of 2010? | The distance D of the earth from the sun is always slowly swinging between its minimum and maximum values. D is minimum (about 147,098,070 kilometers) at "perihelion" around January 3, and D is maximum (about 152,097,700 kilometers) at "aphelion" around July 3. See the article Perihelion and Aphelion. |
| February 21, 2011 | George(New York) | What is the difference between dark matter and dark energy? | Matter and energy are equivalent in the sense that either can be converted into the other, such that the total matter plus energy in the universe, M, never changes. "Dark energy" is a hypothetical energy whose existence would help explain the observed accelerating expansion of the universe. Dark energy is about 73% of M, but only 1 gram in a cube 50,000 kilometers wide. "Dark matter" is also inferred to exist to explain cosmological observations, but is about 23% of M, and more variable in density than is dark energy. Both things are called "dark" because only gravity can "see" them, not light or any other forces. [Sources: Wikipedia and recalled lectures.] |
| February 21, 2011 | Ardhendu(Andhra Pradesh/ India) | What is the creation of universe related with the principles of matter and antimatter and how were the first moments of universe in relation to the same? Thank You | According to the article Baryon asymmetry, "The Big Bang should have produced equal amounts of matter and antimatter... Since this is apparently not the case, after the Big Bang, some physical laws must have acted differently for matter and antimatter. There are competing theories to explain the matter-antimatter imbalance that resulted in baryogenesis, but there is as yet no one consensus theory to explain the phenomenon." |
| February 9, 2011 | AJ | What is pyrite? Is there nickel in it? | Pyrite is a mineral containing iron and sulfur (but no nickel). It has a shiny, golden appearance. It is known as "Fool's Gold" since it is sometimes mistaken for real gold. |
| February 9, 2011 | Anthony (New York) | How far is outer space from the ground, like where we sit and walk on and all of that, if we went straight up? | There is no sharp boundary between our atmosphere and outer space. The atmosphere just gradually gets thinner and thinner. One definition of space is called the Karman line. The Karman line is 100 km up (about 62 miles). NASA uses 122 km (76 miles) as their re-entry altitude, where space shuttles switch over from using thruster rockets to using wing and tail surfaces for steering. |
| February 9, 2011 | Anthony ( New York) | How far is outer space from the ground, like where we sit and walk on and all of that, if we went straight up? | There is no sharp boundary between our atmosphere and outer space. The atmosphere just gradually gets thinner and thinner. One definition of space is called the Karman line. The Karman line is 100 km up (about 62 miles). NASA uses 122 km (76 miles) as their re-entry altitude, where space shuttles switch over from using thruster rockets to using wing and tail surfaces for steering. |
| May 11, 2010 | UMAR (PAKISTAN) | HOW SOLAR AND LUNAR ECLIPSES ARE CAUSED? | Basicaly, an eclipse of the Sun occurs when the Earth passes through the Moon's shadow. A lunar eclipse occurs when the moon passes through the Earth's shadow. For more details visit our web pages Solar Eclipses and Lunar Eclipses |
| May 11, 2010 | Marra (Idaho) | How far away is mars from the sun | The orbits of the planets are not perfectly circular, they have an ellipsoidal shape. Mars inimum distance from Sun is 205 million km (128 million miles) and its maximum distance from Sun is 249 million km (155 million miles). |
| May 11, 2010 | Dorna (Scotland) | how does blackhole act with the light? | According to Einstein's General Relativity Theory, light is also affected by gravity. Black holes are very massive objects with extremely intense gravitational field. There is something call "event horizon" around black holes. It is the point where the gravitational attraction becomes so strong that the velocity at which an object would have to move to escape the gravitational field equals the speed of light. Since the speed of light is, according to the relativity theory, the maximum possible speed, nothing, not even light, could escape the black hole once it is inside the event horizon. |
| May 11, 2010 | joe (minisota) | are you a sientist | You can find information about the members of our group in our web page Windows People. |
| May 11, 2010 | Richard (Britain) | At what height within the Earth's atmosphere does the air become too thin to breathe? | There is not an unique answer to your question. Different bodies reach their limits a different altitudes. However, Mount Everest (altitude 8,800 meters or 29,000 feet) seems to be at the limit at which the human body can survive. Most climbers cannot reach the summit of Everest without the help of supplementary oxygen, though there have been a few extraordinary individuals whose bodies have been able to successfully adapt. More information here. |
| May 11, 2010 | Sam (New Zealand) | Is there a bacteria that uses hydrogen as an energy source, dosen't produce methane and isn't bad for the digestive system? | Yes, there are microorganisms that use hydrogen as an energy source. Such organisms are called hydrogenotrophs, or are described as hydrogenotrophic. See more on this topic here. |
| May 10, 2010 | Clifton (Louisiana/USA) | What is the speed of the earth as it rotates on its axis? | Our planet completes one full rotation in 24 hours. Considering that the circumference of the earth at the equator is 24,901.55 miles (about 40 075 kilometers), a spot on the equator rotates at approximately 1037.5646 miles per hour or 1669.8 km/h. |
| May 10, 2010 | teresia (kenya) | is it true that the earth was formed by a whirling mas of gas? | Your question is answered in detail in our web page Solar System Formation. |
| May 10, 2010 | Rosalie (Washington) | How did the continents split up? | This figure shows the continents united in a super continente called Pangea. The surface of our planet is transformed over long amounts of time, by the process of plate tectonics. |
| May 10, 2010 | Cindy (Republic of the Congo) | What is Jupiter's weather day and night? | We don't know yet as much detail about this giant planet's weather, but what we know is that Jupiter not only has the most dymanic atmospheric motion (including zonal winds which flow west to east, and east to west again), but also the most riveting cloud patterns and storms. |
| May 10, 2010 | Shani (nj) | is titan the largest moon in the solar system? | Titan is the largest moon of the planet Saturn. Titan is the second largest moon in our Solar System. Jupiter's moon Ganymede is the only moon in our Solar System that is larger than Titan. Titan is larger than the planets Mercury and Pluto! |
| May 10, 2010 | Bob (Minnesota) | Is there a constlation in either the nothern or sothern skys that has a circular shape? | Ophiuchus, northwest of the center of the Milky Way, has been some times drawn as having a large circular shape. |
| May 10, 2010 | Jack (CA) | What is the significance of the kingdom Animalia in nature or to humans? | With over 2 million species, Kingdom Animalia is the largest of the kingdoms in terms of its species diversity. Over half of all the animal species belong to a group of animals known as arthropods. Arthropods include animals such as centipedes, crabs, insects, and spiders. All members of this Kingdom share common features, and continuosly interact in Nature. |
| May 4, 2010 | stephanie (united states of america) | is there water on mars? | Laboratory tests aboard NASA's Phoenix Mars Lander have identified water in a soil sample. See full NASA article here. |
| May 4, 2010 | marissa (P.a) | how old is the delta aquarii star? | Delta Aquarii belongs to the Ursa Major Group, an open cluster with stars that formed about 500 million years ago. |
| May 4, 2010 | Bernie | I am an author and am searching for a good sourcebook that would contain information on the night sky around Denver and the adjacent plains. | I personally don't know of such a book, but with Your Sky you can produce maps for any time and date, viewpoint, and observing location. Good luck! |
| May 4, 2010 | Adam (NY, USA) | Will we oneday attempt to restart Mars' Core to allow mars to rebuild its ecosphere and allow us to live there? | Such a project is beyond the knowledge that our civilization has reached. I would even assume that if we were able to do something similar, we would then be able to take better care of our own planet! |
| May 4, 2010 | Judith | A couple of years ago someone sent me a Powerpoint presentation of the Universe, going outwards to larger views, then coming inwards down to a seed on Earth (I think). If you know of this presentation, please could you let me know the site, or put a link to it on your site? | I have seen several of these presentations. I especially like this one, and this one. You can also see a "scale" presentation on our web page A Matter of Scale. |
| May 3, 2010 | Tumelo (South Africa) | which fault is not one of the three types of boundaries between lithospheric plates? | Plate boundaries are found at the edge of the lithospheric plates and are of three types, convergent, divergent and conservative. However, not all plate boundaries are easily defined. One example would be the Mediterranean-Alpine boundary, which involves two major plates and several micro plates. |
| May 3, 2010 | Huma (South Africa) | Where does the majority of earthquakes and volcanoes occurs? | Most earthquakes happen at or near the boundaries between Earth’s tectonic plates because that’s where there is usually a large concentration of faults. Some faults crack through the Earth because of the stress and strain of the moving plates. Other, large faults are the boundary between plates, such as the San Andreas Fault on the North American west coast. See our web page Where Do Earthquakes Happen? for more information. |
| May 3, 2010 | Scott (Utah, U.S.A.) | I was wondering if there was a chance that Pluto could collide with Neptune, when Pluto enters Neptunes Orbital Patern? | Not really, when Pluto is closest to the Sun, and hence closest to Neptune's orbit as viewed from above, it is also the farthest above the ecliptic. |
| May 3, 2010 | Albie (Indian) | suppose a Blackhole appeared just 1cm from Earth,will Earth be safe or will Earth be sucked into the Blackhole? | Black holes are formed as the result of the collapse of a very massive star at its death. They can´t "appear" from nowhere. But let´s assume that they do, then the huge gravitational field of the black hole would surely atract the Earth towards the black hole. |
| May 3, 2010 | Narayanan (India) | Black hole absorbs everything into it.Mass cannot be destroyed.So where do it go?Why don't we think of a star evolving from a black hole? | Black Holes may form as the result of the collapse of a very massive star at its death. All the matter of the star's core is crushed to an infinitely small point, a singularity. Now, although it is true that mass can't be destroyed, it can be transform into energy (that's the meaning of the famous equation E = mc2). Black holes may be an important source of gravitational waves, and may also be important for helping other stars to form. For example the gravity of black holes (like other large stellar objects) may promote nebulae to form stars. |
| May 3, 2010 | KEVIN (INDIA) | why solar cell produce dc supply not ac supply. | The basic principle is that when a photon is absorbed, its energy is given to an electron in the crystal of which the cell is made of. The "hole" left by the electron is occupied by another electron, which now leaves a new hole behind, and so on. This is basically, a direct current being generated. (The whole explanation requieres a lot more space. See, for example, this article for more details. |
| May 3, 2010 | Huma | what is an electro-magnactic spectrum? | The electromagnetic spectrum is defined as the broad range of wavelengths of radiation extending from very short wavelength cosmic rays to the very long wavelength radio waves, and travel through a vacuum at the speed of light. The visible light for humans is just a small fraction of the spectrum. |
| April 27, 2010 | jahnavi.s (india) | is 2012 the movie is true the earth is going to blast on 2012 can u pl answer this ouestion? | There is no scientific fact to support such a catastrophe. Our planet has many more centuries to go. |
| April 26, 2010 | Madison (Nebraska) | What causes differences in the salinity of ocean water in different areas? | There are two important factors to consider: (1) Evaporation increases concentration, so in areas where it is hot evaporation can increase salinity of the surface seawater. (2) Adding water to a solution decreases concentration, so, in areas where it rains frequently and in significant amounts, the salinity of surface seawater decreases. |
| April 26, 2010 | trina (bangladesh) | what will be the fate of a glass of water while pouring it into another glass during staying in moon? | The same question was asked to Planetary Astronomer Mike here, who offered the following answer: "If you pour out water on the Moon, something special will happen. It won't stay liquid water -- it will break up into a fine ice dust. Because there's no air pressure, it boils at room temperature, in other words, it evaporates right away, because there's no pressure keeping the water inside itself. The water molecules are all bouncing around, and now they are free to bounce away in all directions. But the water also freezes as it boils, because its surface area increases so much (it's just little tiny specks of water now) that it radiates all its heat and turns to ice. So boiling and freezing can happen at the same time, when there's no air." |
| April 26, 2010 | isacc (florida) | is their any other planet out there | With the new clasification of Dwarf Planets, there a list of new planets that keeps growing. There are also extrasolar planets, or planets found orbint a different star than our sun. |
| April 26, 2010 | Luis (Florida) | Why isn't Sedna listed as one of the dwarf planets? | 90377 Sedna is a trans-Neptunian object and a likely dwarf planet discovered by Michael Brown (Caltech), Chad Trujillo (Gemini Observatory) and David Rabinowitz (Yale University) on November 14, 2003. Sedna currewntly is a dwarf planet candidate. Visit our web page New planetoid named Sedna discovered for more information. |
| April 26, 2010 | ASIF (pakistan) | I want to ask why everybody thinks STRING THEORY is correct,Is there any other approach to consider, to unify these four forces? | Not everyone. The String Theory is still under a heated discussion among the theoretical physicists. Visit this forum for a taste of the discussion. |
| April 26, 2010 | Amatullah (Pennsyvania) | Why do the planets have symbols? | The planetary symbols, along with symbols for the Moon, Sun, and even constellations, were developed for use in astronomy and astrology, and are of very ancient origin. Early versions of the planetary symbols were already used in Bianchini's planisphere, from around the 2nd century. |
| April 23, 2010 | Pearl (Canada) | Can you please explain to me the effects of the Atlantic Thermohaline Circulation and what would happen if it got thrown off or stalled as the level of salinity changed | Our web pages Thermohaline Circulation: The Global Ocean Conveyor and Thermohaline Ocean Circulation describe and discuss in detail this topic. |
| April 23, 2010 | julia (finland) | how and why do day lengths change across europe with latitude and season? | Seasons and the lenght of the day are related with the tilt of our planet axis. It is known that the length of a day varies throughout the year, and depends upon latitude. This variation is caused by the tilt of the Earth's axis of rotation with respect to the vertical. At solstices (June and December 20-22), one of the poles is tilted toward the sun. The hemisphere that is tilted toward the sun has days ranging in duration from just over 12 hours around the equator to 24 hours in the polar circle, while the opposite hemisphere has days ranging in duration from just under 12 hours around the equator to zero in the polar circle. At the equinox (about September 22-23) the poles are neither tilted toward nor away from the sun, and the duration of a day is generally about 12 hours all over the earth. |
| April 23, 2010 | divya (india) | is there any mathematical proof of "the time period of moon's revolution around earth is equal to its period of rotation" | See, for example, Almost Periodic Functions and Hill's Theory of Lunar Perigee. Aurel Wintner. American Journal of Mathematics, Vol. 59, No. 4 (Oct., 1937), pp. 795-802. |
| April 23, 2010 | Julia (USA) | What are the Major Missions to Venus? | Our web page Missions to Venus offers the information you need. |
| April 23, 2010 | Katie (IL,USA) | what is Jupiter's diameter? | Jupiter's diameter is 142,800 km (88,736 miles) |
| April 23, 2010 | Christopher (NC) | What is the spot on neptune is it a storm or a hole or something, what is it? | Unlike Jupiter's Great Red Spot, the Great Dark Spot of Neptune is thought to be a hole, similar to the hole in the ozone layer on Earth, in the methane cloud deck of Neptune. More information on our web page Neptune's Great Dark Spot of 1989. |
| April 23, 2010 | robert (new york) | when can we see neptune at night in new york | Neptune will spend almost all of 2010 in Capricornus, south of the celestial equator. Neptune will never get very high in the sky for people at mid-northern latitudes. Ask for an adult help to use this chart to locate Neptune in the night sky. |
| April 23, 2010 | Rahul (India) | why are galaxies moving from each other | The most accepted theory about the origin of the universe is the Big Bang. This explains why the galaxies move away from each other as a result of the Expanding Universe. |
| April 23, 2010 | simi (ON) | which scientist has work associated with the sun(full name plese)and which was the first spacecraft to observe the sun | Pioneers 6,7,8, and 9 (respectively launched on 16 December 1965, 17 August 1966, 13 December 1967, and 8 November 1968) were the world's first solar monitoring network and provided warnings of increased solar activity which could affect Earth orbiting satellites and ground systems |
| April 23, 2010 | alice (washington) | is it possible to have a thermometer shatter when it gets to hot | Yes! Be careful when handly thermometers, they can shatter when the temperature rises beyond the thermometer limit. |
| April 23, 2010 | Bradley (wv) | do magnets affect plant growth? | Yes, as early as 1862, Louis Pasteur discovered that magnetism affects plant growth when he was experimenting on the fundamentals of fermentation. See this intereting article for more information on this topic. |
| April 22, 2010 | Tony (England) | SIR What is causing the blue ring on the moon as viewed fromthe UK. | The scientific explanation is that the blue ring is caused by tiny ice particles in the upper layers of the atmosphere, which give some credibility to the legend that the blue ring will be followed by snow or rain. |
| April 22, 2010 | conner (noeth corlina) | how to live on jupiter | Jupiter is one of the gas planets, with temperatures at cloud tops of about -150oC (-101oF). Jupiter's interior composition is primarily that of simple molecules such as hydrogen and helium, which are liquids under the high pressure environments found in the interiors of the outer planets, and not solids. As you can see, it would be very hard to live there! |
| April 22, 2010 | angela (ohio) | why is it called the gas planet | The interior or rocky planets (Mercury, Venus, Earth, and Mars)are mostly made up of rock and metal. These planets are very heavy and move slowly. The giant, jovian or gas planets (Jupiter, Saturn, Uranus, and Neptune) are composed primarily of hydrogen and helium and generally have low densities, rapid rotation, deep atmospheres, rings and lots of satellites. |
| April 22, 2010 | gabby (california) | who discovered the first nebula? | I believe it was the Crab Nebula was before observed by John Bevis in 1731; it corresponds to a bright supernova recorded by Chinese and Arab astronomers in 1054. It was cataloged by Charles Messier in 1758 as M1. |
| April 21, 2010 | Krista (Texas) | What are the temperature ranges for the moon? | The temperatures on the Moon are extreme, ranging from 100° C at noon to -173° C at night. More information on our web page The Earth's Moon. |
| April 21, 2010 | Krista (USA) | What is the diameter of the Moon in miles? | Moon's diameter is 3 474 km or about 2 160 miles. |
| April 21, 2010 | Taylor (USA) | Which takes the most amount of time? Earth rotates once or Earth revolves once or The moon revolves once or All take the same amount of time. | Our planet Revolution Period about the Sun (Length of a Year) is 365 days 5 hrs, and its Rotation Period with respect to Sun (Length of Day) is 24 hrs. It takes the Moon the same amount of time, 27.322 days, to rotate around once as it does for the Moon to go around the Earth once. |
| April 21, 2010 | carl (england) | if i have the weight of a object and know the speed per min how do i work out the newton force on the ground | From your question it seems the object in question is free falling under the attraction of the gravitational field, and the value of the acceleration (rate of change of the velocity) is given (in our planet, at sea level, it is g = 9.8 m/s2). Using Conservation of energy and assuming the object started moving from rest: Potential energy at the highest point P = mgh, (mass times acceleration of gravity times height), while kinetic energy K = ½ m v2 (1/2 mass times velocity square) = 0 At the instant before the impact, P = 0 (because h = 0), and K = ½ m V2, which means that all the potential energy was converted to kinetic energy. So, Initial P = Final K, or mgh = ½ m V2 From here, the final or impact velocity just before the impact Vf = square root(2gh). Now, from the work-energy theorem, work = force times distance = change of kinetic energy, W = F.d = ½ m Vf2 - ½ m Vi2, but Vi = 0 , then, Fimpact = (½ m Vf2)/d |
| April 20, 2010 | Jackson (Va Beach) | What is acid snow and what is it's scientific name? | Acid snow, as acid rain is a form of precipitation unusually acidic. It can have harmful effects on plants, aquatic animals, and infrastructure. |
| April 20, 2010 | Joshua (CA) | What would happen to the Earth's moon if inertia went away? | Although inertia is an inherent property of all bodies (and therefore the case you are asking about is not possible in nature), we still can imagine what would happen. Just tie a small object to the end of a string and start moving it in circles, then, being careful, release it. You will see that the object will fly away in a tangential direction to the circles. The same would happen to any body moving on a circular path that is suddenly released! |
| April 20, 2010 | carol (south carilina) | how many mercury's fit in one earth? | The diameter of ou planet is 12 753 km (7,926 miles). The diameter of Mercury is 4 878 km (3,030 miles), or about three times smaller. So, for covering the face of Earth a little less than 3 mercuries would be lined end to end. Now, if we want to fit mercuries inside our planet, like marbles inside a bowl, then we will have to stretch the marbles in the bowl, or the mercuries in the earth, in three directions; up-down, in-out and left-right, or 3 x 3 x 3 = 9 (remember that it actually is less than 3 mercuries side by side, so the actual result is less than 9.) |
| April 20, 2010 | Sam (NJ) | Can you please tell me the Apparent magnitude, Absolute magnitude, Surface Temperature, Class, Distance from Earth, and what is it named, for the constellation HERCULES? | The questions you asked apply to stars. For example, Mu Herculis is a nearby star system (about 27.4 light years from Earth) in the constellation Hercules with the following characteristics: Apparent magnitude (V) 3.42/10.35/10.80 Absolute magnitude (MV) 3.80/10.73/11.18 Mass 1.1/0.31/0.31 M¨‘ Radius 1.8/0.48/0.4 R¨‘ Luminosity 2.2-2.7/0.005/0.003 L¨‘ Temperature 5,500 K Spectral type G5 IV/M3.5 V/M4 V Hercules constellation is named after Hercules, the Roman mythological hero. |
| April 20, 2010 | Zoe (Ilinois) | What happens if you go in a black hole? | From our web page Black Holes: What would it be like to enter a black hole? Not pleasant. First, as you approach the black hole the difference in the gravitaional pull on your head compared to your feet (known as tidal forces) would rip you apart. But suppose you survived that. Once you cross the event horizon there is no turning back. Then the only thing to do is avoid the black hole itself at all costs. If you run into that singularity it will crush your body right out of existence. If people from Earth were watching your journey into a black hole they would never see you cross the event horizon. Albert Einstein's theory of General Relativity says that as you approach a black hole your time slows down. The closer you get to the black hole the more you appear to be in slow motion as seen by Earth. Eventually you appear to be frozen in time as you cross the event horizon. You would notice nothing different whatsoever. If you were to change your mind right before crossing the event horizon and return to Earth you would find it in the very distant future. You've become a time traveler! |
| April 20, 2010 | Albie (India) | What is a Light-year | A light-year is a unit of distance. It is the distance that the light travels in a year (assuming it is moving in a vaccum). 1 light year = 9.4605284 × 1015 meters or 9 460 528 400 000 km. |
| April 20, 2010 | Albie (India) | where does electricity come from? | In the most simple definition, electricity is just the motion or flow of charged particles (of which all substances are made of) between two points. |
| April 2, 2010 | aiman (pakistan) | what is ridge made of | A ridge is a continuous elevational crest for some distance. There are several types of ridges, one of them is the oceanic spreading ridge, in tectonic spreading zones such as at the Mid-Atlantic Ridge, where the volcanic activity forming new plate boundary forms volcanic ridges at the spreading zone. |
| April 2, 2010 | aiman (pakistan) | name the plates that lies on each side of the ridge | The main force that shapes our planet’s surface over long amounts of time is the movement of Earth's outer layer by the process of plate tectonics. |
| April 2, 2010 | lauren (canada) | how long will it take you to get from the earth to saturn | Let's take a look at the missions to Saturn as they arrived: 1st mission: Pioneer 11. Launched: April 5, 1973, arrived: September 1, 1979. Total flight time: almost 6 years and 5 months. 2nd mission: Voyager 1. Launched: September 5, 1977, arrived: November 12, 1980. Total flight time: 3 years and 2 months. 3rd mission: Voyager 2. Launched: August 20, 1977, arrived: August 26, 1981. Total flight time: of just over 4 year. 4th mission: Cassini. Launched: October 15, 1997, arrived: July 1, 2004. Total flight time: of around 6 years and 9 months (the delay of this mission was due to several flybys of other planets to gain additional velocity). Fastest mission: New Horizons. Launched: January 19, 2006, passed the orbit of Saturn: June 8, 2008 Total flight time: 2 years and 4 months. |
| April 2, 2010 | Albie (Kerla/India) | What is a Nebule? please explain | A nebula (pural nebulae) is an interstellar cloud of dust, hydrogen gas, helium gas and plasma. |
| April 2, 2010 | deborah (san bernardino, CA) | why we can not see the planets move in a telescope. | They are very far from us. But you should be able to see their change of position for day to day! |
| April 1, 2010 | emily (north carolina) | what percent of raditation is lost before reaching earths surface? | Less than 20 percent of the solar radiation reaching Earth is absorbed by atmospheric gases and clouds, 50% is absorbed by Earth's surface--mostly the ocean, and 31% is reflected back to space. |
| April 1, 2010 | gianelli (philippines) | why do galaxies' shapes differ? | Just very recently, astronomers have explained the diversity of galaxy shapes seen in the universe. The scientists, Dr Andrew Benson of the California Institute of Technology (Caltech) and Dr Nick Devereux of Embry-Riddle University in Arizona, tracked the evolution of galaxies over thirteen billion years from the early Universe to the present day. This article describes in more details their research, but in short, their model suggests that the number of mergers between very large haloes of dark matter and the galaxies they surround, drives the final outcome—elliptical galaxies result from multiple galaxy mergers whereas disc galaxies have seen none at all. |
| April 1, 2010 | Albie (India) | who was the first scientist? what was his name? what did he find? | Some people consider Galileo Galilei to be the first scientist because his spectacular work in the sixteenth century, but Roger Beacon already advocated experimentation in the thirteenth century (one of Bacon's books, Perspectiva (Optics) includes several experiments with all the steps of the scientific method). Yet other people consider Ibn al-Haytham (born in Basra, in what is now Iraq) in 965, to be the first scientist. He wrote more than 200 books and treatises on a wide range of subjects. He was the first person to apply algebra to geometry, founding the branch mathematics known as analytic geometry. |
| April 1, 2010 | Albie (India) | I have heard that "after the Earth was made,thunderstorms came to start life'' Is It true? if yes,please Explain. | The most common hypothesis in the scientific community is that life began approximately 3.5 billion years ago as the result of a complex sequence of chemical reactions that took place spontaneously in Earth's atmosphere. In the 1950's, two biochemists conducted an experiment which showed that certain molecules of life (amino acids) could form spontaneously when the conditions of Earth's early atmosphere were recreated in the lab. It is assumed that over time, these molecules interacted with one another eventually leading to the earliest forms of life. More information on our web page The Origin of Life on Earth . |
| March 30, 2010 | Sam (USA) | What is the rotational relationship between the earth and the sun that causes day and night? | The main reason for the day-night sequence is the rotation of our planet on its own axis. It takes near 24 hours to complete a full rotation, and during this period, the planet shows different parts to the Sun. The side of the planets facing the Sun will be day, the opposite, night. |
| March 30, 2010 | ayisha (oman) | why does meteorites not fall on earth/ | But they do! A meteorite is a natural object originating in outer space that survives impact with the Earth's surface. |
| March 30, 2010 | Albie (India) | How did the Solar System Begin?How will it end? | You can find the answer to your question in our page Solar System Formation. |
| March 30, 2010 | mauricio (mexico, sinaloa) | caracterisar el conseptode precion. interpretarlo con el punto de viste microscopico y dar algunos valores caracteriticos. | En física y disciplinas afines, la presión es una magnitud física que mide la fuerza por unidad de superficie. Por ejemplo,la presión atmosférica al nivel del mar, la fuerza por unidad de área debida al peso de la atmósfera, es de 760 mmHg o 101300 pascales (101.3 kPa). |
| March 30, 2010 | mauricio (mexico, sinaloa) | explicar el origen de la fluides y gases | Un fluido es una sustancia que esta en estado líquido, gaseoso, o plasma, y que debido a su poca cohesión intermolecular, carece de forma propia y adopta la forma del recipiente que lo contiene. |
| March 30, 2010 | Emily (Michigan) | Please explain which Domain is the Kingdom of Monera in and how it fits in with the Eukaryota Domain. Thank you! | The Monera kingdom included most organisms with a prokaryotic cell organization (no nucleus). For this reason, the kingdom was sometimes called Prokaryota or Prokaryotae. Under the three-domain system of taxonomy established in 1991, the organisms formerly within Monera have been divided into two domains, Archaea and Bacteria (with Eukaryote as the third domain). |
| March 29, 2010 | hanah (california USA) | How come Earth has oxygen and other planets do not? | The Earth receives most of its oxygen from photosynthetic activity, the process by which plants convert water, carbon dioxide, and solar energy into sugars and oxygen. There are no known plants on other planets, therefore, no production of oxygen by photosynthesis. |
| March 29, 2010 | Philip (Great Britain) | Why was the moon's orbit seem to be in a north/south orbital direction | The Moon's apparent orbit is in the east-west direction. The Moon appears to move completely around the celestial sphere once in about 27.3 days as observed from the Earth. Since the Moon must move Eastward among the constellations enough to go completely around the sky (360 degrees) in 27.3 days, it must move Eastward by 13.2 degrees each day. Thus, with respect to the background constellations the Moon will be about 13.2 degrees further East each day. More information here. |
| March 29, 2010 | jennifer (canada) | Is there 100 year old storm on jupiter? | Jupiter's Great Red Spot is a storm that has been present for centuries, first observed by Galileo 400 years ago. The storm lies in the southern hemisphere and is about 30,000 kilometers by 14,000 kilometers, much larger than the planet Earth! |
| March 29, 2010 | Brian (New york) | Who found Saturn & its rings? I am in a rush so please answer. | Like the inner planets and Jupiter, Saturn is clearly visible in the night sky. The ancient Greeks named the planet after the god of agriculture and time. It wasn't until 1655, however, that we knew Saturn had rings. Galileo saw two lumps on either side of Saturn, be he didn't know what they were. The astronomer Christian Huygens later found out they were rings. |
| March 29, 2010 | Natalie (USA) | Witch star is the farthest away from earth? | With the Hubble telescope and using an exposure time of several hours, one can see stars to about 30th magnitude. This is about 10 billion times fainter than our Sun, if it were 32.6 light years away. Since there are 1020 or more stars within the visible universe, it is almost impossible to identify which one is farthest. |
| March 29, 2010 | Nicole (California) | is it fun going to space? | Read this interview with astronaut Chris Hadfield. I am sure you will agree with me that they have lots of fun! |
| March 26, 2010 | Elaine (PHILIPPINES) | WHY DO MOST EARTHQUAKES OCCUR ALONG A FAULT LINE? | When the giant blocks of rock that make up the Earth's crust are moved by plate tectonics, they are bound to bump into each other sometimes. These blocks of rock come in contact at faults. Sometimes they slide smoothly past each other. Other times the rocks get stuck - the rough surfaces of rock snag and they can't move along the fault. That might lead to an earthquake. MOre information on our web page Why Do Earthquakes Happen?. |
| March 26, 2010 | Delilah (NM) | Dose pluto have an atmosphere? | It may seem hard to believe that Pluto could have an atmosphere because it is so cold at 39 AU, where Pluto is found, but it does. Because there are times when Pluto is closer to the sun than is Neptune (making it the 8th planet for roughly 20 years at a time), ices on Pluto's surface evaporate and form an atmosphere. It is continually produced and lost again as long as Pluto is inside Neptune's orbit. |
| March 26, 2010 | EL (PHILIPPINES) | HOW WERE THE CONSTELLATION OF THE ZODIAC CHOSEN? | A probable cause for being chosen as the zodiac signs would be that they fall within the plane of the ecliptic. |
| March 26, 2010 | veronica (philippines) | who was the first scientist? | Some people consider Galileo Galilei to be the first scientist because his spectacular work in the sixteenth century, but Roger Beacon already advocated experimentation in the thirteenth century (one of Bacon's books, Perspectiva (Optics) includes several experiments with all the steps of the scientific method). Yet other people consider Ibn al-Haytham (born in Basra, in what is now Iraq) in 965, to be the first scientist. He wrote more than 200 books and treatises on a wide range of subjects. He was the first person to apply algebra to geometry, founding the branch mathematics known as analytic geometry. |
| March 26, 2010 | carl (canada) | hi, i was wondering if you could help me i have to do a expermient on the solar system , for a grade 3 science fair can you help me | Look, for example, at our A Solar System Model Builders Guide for directions to build a scale model of the solar system. |
| March 26, 2010 | Albie (kuwait) | does life exist in KBO? | No life has not been found at any of the Kuiper Belt objects. Actually, life has not been found anywhere outside Earth. |
| March 26, 2010 | Mike (Oklahoma/USA) | Why are there no new natural species animals or plants occuring on the earth? | Each year the Arizona State University's International Institute for Species Exploration (IISE) announces a list of the Top 10 New Species discovered the preceding calendar year. The Top 10 New Species described in 2008, are listed here with links to additional details about each species. |
