If the moon's size is the same as the Earth's ,is life possible on both planets?
442996
THe main issue with the Moon being the same size as the earth is that the moon would no longer be pulled in by the earth's gravitional pull. The planets would either settle into seperate orbits or collide and kill us all.\n\nThat aside, the size of Earth is one factor determing wether or not life is supportable. Other important factors are the tilt (has to be within 3 degrees if I remeber correcctly) and it's distance from the sun. \n\nI have heard of the theory of an 'anti-earth', a tehrotical earth on the oppsite side of our orbit with the same chactersitics as our planet and therefore capable of life. This might be starying into the realm oif sci-fi though
410440
Assuming life on earth still existed and that water\ncould still be found (not all frozen), the tides \nwould be smaller, because the Moon influences the\ntides about 90% but the other 10% influence comes\nfrom the Sun's gravitational force... That's why\nthe tides are higher at New Moon and Full Moon, \nbecause both the Moon and Sun are pulling along\nthe same line, whereas at first quarter and last\nquarter Moon, the tides are relatively lower, \nsince the Sun and Moon's gravitation somewhat\ncancells each other out
370080
Finally a good question.\n\nThe Moon's apparent size being very similar to the Sun's apparent size is a coincidence. But the Moon doesn't always cover the Sun during an eclipse, look up annular eclipse (the looks smaller), and when it does cover it, it is usually a bit larger.\n\nBut now let's talk about the main question.\n\nWe always see the same side of the Moon because its during its full rotation around the Earth it also makes a full rotation around its axis. This is not a coincidence. There are several satellites in the solar system whose rotation is synchronized with their rotation around a planet (eg. Io around Jupiter, Charon around Pluto but also Pluto around Charon :-) etc. ).\n\nThe Earth's gravitation decreases with the distance from its center. So the Moon's opposite side (which is further away from the Earth) is attracted less by the Earth than the side which is closer. This results in the Moon being a little bit deformed along the Earth-Moon line.\nThe Moon is a little bit shaped like an egg: if it would rotate faster, it would not be elongated towards the Earth anymore, and the Earth's gravitation would try to turn it back. This is very difficult to explain without the opportunity to draw figures ... but anyway, search for tidal locking on the net, I hope you'll find a good, illustrated explanation.\n\n\nEDIT: In one answer someone said that Mercury is in a similar relation with the Sun ... this is not exactly true, as the ratio of period of its rotation and the period of its orbiting is 3/2.\n\nMercury also has an elongated shape: due to this 3:2 resonance, at its perihelion, the axis of its elongation is always parallel with the Sun--Mercury axis.\n\nEDIT2: As I said, the apparent size of the Moon is just a concidence. Other planents do get total eclipses. What does a total eclipse mean? It means that a moon casts a shadow on the planet: http://www.c-science.com/txt/images/1999/990428unssx2.jpg\n\nThere is a nice program calles Celestia, which can show you the eclipses caused by various moons on various planets (3D animations): http://www.shatters.net/celestia/
857828
1- yup, Earth\n2 - The sun is about 400 times the diameter of the moon, but is also about 400 times farther away\n3 - Cosmic rays ( a form of electromagnetic energy that would sterilize the surface of our planet within a few months if not blocked ), and meteors, thousands of which would hit us every hour.
736681
During my Time Travels I did do some Intergalactic Exploration. When I was in Grid 946 Quadrilateral 47, the solar system was similar to your solar system. Basically we ( my Friends and myself) observed than any planetary structure is protected from outside forces due to Gravity and Atmosphere. Moons, as you are accustomed to calling them lack those two important aspects, thus, any outside forces bombard those structures and they similar to the moon as larger structures with gravity and atmosphere are similar to Earth. It simple Physics according to Earth's Concept. Once your Scientist understand Dimensions, then you understand the many things you now consider mystery.
220501
Considering that we are of the same stuff that all other life on Earth is made of, it seems very unlikely.  Of course that does not eliminate the possibility that life on Earth was seeded from some outside source 2 billion years ago.
239488
Predictions suggest that the range will increase until the Earth and Moon become double synchronised, that is, both are tidally locked to one another. The Earth-Moon distance would then be about 550000km. This won't occur for something like 50 billion years. Before then, though, our Sun will have died, and both the Earth and Moon almost certainly won't even exist.\n\nThis website for answer confirmation and more info  -->http://www.madsci.org/posts/archives/apr2002/1020171327.As.r.html\n\nGod is spelled B-I-G B-A-N-G\nPBrax@netscape.com
1077788
Life on other planets is possible. Think about the billion other planets out there. Scientist have discovered that there are other planets capable of sustaining life, even if there weren't, plants can grow in space, therefore ecosystems can be built on other planets to produce oxygen. How long will it take us? As long as we realize we are all humans and we stop fighting over oil and money.
809106
No because no planet has exactly the same living conditions which ours provide. And we know thtat any slight change in the composition of gases or the distance of the sun in relation to the earth can have a darmatic impact if not fatal one on our lives
336486
No.  \nHere is why: Although the list of known extra-solar planets is growing, to my knowledge, none have been described where there are two in the same orbit.  In terms of solar planets (ie us) although it is true that two planets in our solar system cross orbits, this is not 'sharing' the same orbit (at least in the sense of your question I think).  It seems possible enough, but has not yet been described.
82957
Maybe. It seems that in a universe filled with billions of galaxies, each with billions of stars, each with a potential to have a planet with life around it, that at least a few other planets would have to have life. It is not reasonable to suppose this is the only one where this ever happened. \n\nHowever, you asked about "creatures like humans". This is possible, but no where near as likely as there simply being "life" on other planets. The forces of natural selection ("evolution") can develop life in a myriad of possible shapes, and there is no guarantee that human-like lifeforms will evolve anywhere else. By some points of view, it is virtually impossible since a great many events happened over billions of years that resulted in us looking like we do. There might be life out there, and even intelligent life, but it is probably very different from us. \n\nHowever, another way to look at it finds the possibility that there is life like humans out there. Think about this: how many ways are there to get around: swimming, crawling, brachiating (swinging from trees), flying, walking. Maybe there are a few more that we don't see on Earth. Legs are one of the best ways of getting around, so it seems likely that, if there are many different worlds with life, a large proportion of those worlds have creatures with legs. This same logic applies to arms and hands--how many effective ways are there for manipulation of objects? Tentacles, cilia-like graspers, lobster claws, hands, and probably more. Still, something like hands at the end of flexible or jointed extensions like arms is a very good means of allowing a creature to grab things and shape them, so it seems likely that something hand-like will also appear. And then there are the obvious advantages of having the head on top of the body, for standing upright, for having two eyes set horizontally, etc... \n\nWhat I am getting at here is that there might be a million million ways that lifeforms can be shaped, but perhaps there are only a limited number of forms capable of inventing and building cities or ships or plows etc... Since the ability to create these things have such obvious advantages, life might often be "channeled" by the force of natural selection into the forms that allow technology, and therefore a human-like form might be seen more than just here on Earth.
704661
Yes. The moon is a satellite of the earth and it, along with all the other planets and moons in our planetary system go about  making up our solar system.\n\nSolar system meaning our planetary system rotating around our sun and our sun being referred to as sol, thus becomes our solar system. \n\nGood question, \n\nDarryl S.
285815
The probability of life on other planets (or moons) is certainly given. Just the other day a spacecraft found liquid water and volcanic activity on Saturn's moon Enceladus. So it's quite possible there could be life, in a primitive form at least, as near as Saturn's environment.\nAs to other galaxies, we'll never know. It's too far away - we're talking millions and billions of light-years. So even if there was life in other galaxies, the information to reach us would take millions and billions of years.\nGoing there is out of the question. Mass can't even reach the speed of light, meaning that to go to the nearest star, Alpha Centauri (four light-years away), would take very long. With a Space Shuttle, you can go at 28000 kph (17,500 mph). Light travels at 300000 kilometres per second (186,000 miles per second)! This equals 1080000000 kph (675,000,000 mph).\nSo given today's technology it would take slightly more than  150,000 years only to reach Alpha Centauri.\nBetter make sure to have a good book on board with you.
519780
I think would would see all phases of the Earth if you was on the moon. Just opposite from the way it is on Earth.
1139974
It may well be!\n\nThe problem is that we haven't really looked. It's true that the probes we've sent around our own solar system have drawn a blank when it comes to life. Life as we know it seems to prefer a certain range of temperatures and habitats, and those conditions aren't all that common. But they do exist, both here in our solar system and (almost certainly) in other solar systems as well.
205427
It is very likely that the Moon was formed out of Earth. The Moon and Earth are composed of the same material suggesting that they were formed out of the same object meaning it is far less likely that the moon formed elsewhere in the solarsystem and was later captured by earth. Also such a large body would not allow itself to be captured. \n\nCould the Moon and Earth have simply formed at the same time by the same debris (as statetd below)? Also very unlikely as this would mean the Moon should have the same amount of heavier elements that Earth has. But the Moon is only composed of lighter materials, the same stuff the earths crust is made out of. \n\nThe only way the Moon could have been formed out of Earths crust is by the collision of another body the size of Mars. If the protoearth would have suffered such an impact in its youth at the right angle, a portion of Earths crust could have been thrown into space with most of it falling back down (this has also been confirmed as a viable theory from supercomputer simulations). A smaller portion would then have remained in an orbit to form the Moon. This collision-ejection theory is the only one that can explain for the other characteristics of the Moon such as the fact that the Moon is absolutely bone dry while Earth has loads of minerals with a large water component.
602526
No body know for certain. However, the universe is so vast, with so many celestial bodies that it seems rather improbable if the only place in the whole mutiverse that harbors life is planet Earth.