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Archive 1 | Archive 2 | Archive 3 | Archive 4 | Archive 5 |
This is Archive 2 covering 2004.
How did the Earth form? What aspect of the Earth or its location do astrobiologists hypothesize as having been crucial to the development of its most idiosyncratic feature-- life. How did life emerge and when. Have there been any noteworthy biological events since the appearance of the first cell? How does the emergence and history of life relate to geological and climate evolution? How often is Earth hit by asteroids? What have been the consequences? Do we expect more?
How did scientists determine the average density of the earth? - The average density is Mass divided by Volume. To find the volume you need the radius which you can find by measuring the curvature of the Earth like Eratostenes did about 230BC. Then you know the volume of the Earth (assuming it is sufficiently spherical). To measure the mass you need to know the gravitational constant which was measured sometime I believe sometime in the 18th century. You apply Newton's law for gravity (the one with inverse-square radius) and you have the mass.
How many human-made satellites are there and when did the first one ( sputnik) go up? If you count every single piece of manmade debris - millions. Sputnik - October 4th 1957.
How do people study the Earth? What kind of scientists study it? What questions plague us, if any? What are predicted fates of the Earth? What about the ozone hole? What about the Kyoto protocol? What about geomagnetic reversals? 168... 05:22, 17 Jan 2004 (UTC)
Nearly all humans live on Earth: 6,327,152,352 inhabitants (November 1, 2003 est.)
User:Cantus has twice removed this statement from the intro paragraph: "the largest terrestrial planet in the solar system." I disagree with the reasons he's stated in the edit summaries (first that Jupiter's core might be larger, and then that it was "anecdotal"), and think it is a totally reasonable thing to say in the intro. Cantus, could you explain in greater detail why you think it should be removed? Bryan 04:27, 25 Mar 2004 (UTC)
I don't think there's any credible evidence of any terrestrial planet our solar system that is larger than earth. Cantus' objections are absurd. I say if it gets removed in the future, that should be considered vandalism unless there's a damn good explanation. -- Doradus 01:45, Sep 23, 2004 (UTC)
Bryan Derksen, where are you getting that mean temperature from? Averaging the min and max gives 258, not 282... If that average temp. was obtained thru a different method, care to mention the source? -- Cantus 06:00, 25 Mar 2004 (UTC)
the moon is not the only "natural satellite". E.g. the earth has captured an asteroid named Cruithne.
about mentioning the moon in a short article about earth: it's important. On this level, the earth is nothing than a planet among 9 others. The number of moons is characteristic and has to be meantioned.
I get 365.25636 / 365.2422 ≈ 1.00003877. Fredrik (talk) 19:25, 16 Jun 2004 (UTC)
The planet is big enough to have the core differentiated into a liquid outer core, which gives rise to a weak magnetic field due to the convection of its electrically conductive material, and a solid inner core.
It is generally believed that the rotation of the inner core (which is primarily composed of iron) creates the Earth's magnetic field. It is not known, exactly, why this occurs.
I think this is confusing. What is causing the magnetic field - inner or outer core? Are there two components of the field? This needs to be clarified. Paranoid 11:02, 23 Jun 2004 (UTC)
Does this need to be in this article? Do we even have a source for it? Edward 10:01, 25 Jun 2004 (UTC)
Inclination of Earth's orbit is given as 0.00005 degrees. Since this is the inclination to the Ecliptic, shouldn't this be 0 by definition? If the value given is related to some other plane, shouldn't that be made clear? Thanks. Amorim Parga 04:21, 17 Jul 2004 (UTC)
Shouldn't the entry say "Mostly harmless." ?? Just drooling. ;-)
Someone attempted to add a comparison of the torques felt on the Earth by different astronomical objects in order to explain why the moon has a stabalizing effect on the axis of the Earth. For one thing, this is rather technical information and might not fit very well into this page, but worse than that, the numbers quoted were simply very wrong. It is clear from the scale of the numbers stated that the author was merely comparing the force exerted on the Earth from various astronomical objects. However the force is not the same as the torque. The torque depends not on the total force but on the difference in the force applied to one side of the equatorial bulge rather than the other. Because it is so close, the moon has the largest gravitational gradient across the Earth of any astronomical object (followed shortly thereafter by the sun). Hence, the Moon exerts the largest torque on the Earth and that is why the moon acts to stabilizes the Earth's axial tilt.
However, other factors are also important. For example, relatively constant torques, such as from the Moon and Sun tend to cause axial precession and not nutations or axial tilts. For other planets (e.g. Mars) the total torques exerted depend more significantly on where it is in its orbit with respect to its nearest neighbors (e.g. Earth and Jupiter). It is when such time varying torques are a significant component of the total torque that one tends to promote chaotic shifts in the planet's axis.
Dragons flight 18:56, Sep 11, 2004 (UTC)
Seems that the complex and as stated controversial subject of chaotic instability of Earth's axial tilt under moon should be moved to another article, maybe to axial tilt, rather than in this long general article. - Vsmith 01:49, 17 Oct 2004 (UTC)
Cantus wrote: Encyclopedias are not written for aliens or animals. So what's wrong with aliens (or animals) reading Wikipedia? — Monedula 11:55, 12 Sep 2004 (UTC)
Can we remove the specific number and round to the nearest 10,000? I'm pretty sure we haven't been able to get even that accurate as it is. Oberiko 17:10, 17 Sep 2004 (UTC)
An anonymous user changed the surface area very slightly. I haven't done any calculations, but the change may even be within the error margin. However, I feared that this was one of the slashdot-inspired changes designed to evaluate the efficiency of Wikipedia peer review, so I'd like to find a recent supporting source for one of the numbers. However, my efforts of googling something up have been unsuccessful. Help? — David Remahl 20:32, 22 Sep 2004 (UTC)
I can contribute some calculations. Hopefully it's good enough to assume an oblate spheroid with polar radius 6356.78km and equatorial radius 6378.14km, which are taken from our own Earth page (but which are more precise than the values listed in NASA's planetary fact sheet).
First, the eccentricity is defined by:
Solving for eccentricity e:
Plugging into the formula for the area of an oblate spheroid:
This is evidently the calculation performed by the anonymous editor. However, carrying it to the nearest square kilometer is excessive, since (for instance) that implies that the radius figures are accurate to the nearest centimeter (!!), and is also far beyond the accuracy of the oblate spheroid approximation. Certainly 510,067,000km² is more than enough precision. -- Doradus 02:48, Sep 23, 2004 (UTC)
An unimportant point regarding the surface area of the Earth: the actual surface area of the Earth is slightly smaller than the surface area as calculated from its radius. This is due to the Earth's gravitational warping of space-time, and the difference is about an acre (about half a hectare).-- B.d.mills 11:06, 29 Oct 2004 (UTC)
I recently read a rather interesting article in Science News or in New Scientist about a theory that the Earth may have a Uranium core deep inside our Iron core. The main thesis of this theory is that it accounts for otherwise inexplicable levels of energy.
Unfortunately I don't have the citations at hand and I'd be reluctant to add references to this theory without some discussion of it's merits. (In any event it would be posed only as a short counterpoint paragraph to the comment about the core's putative lack of heavier elements, especially uranium.
Here's one older link: Discover, August, 2002. (Normally I wouldn't consider Discover to be a compellingly credible source --- but I'm sure I read this elsewhere and was impressed with the logic of the theory).
JimD 20:11, 2004 Sep 26 (UTC)
Where it says on the first line "Earth, the planet on which we live", that may be incorrect if aliens from another planet grasp satelite signals from our planet. In that case, we may offend them and they could sue Wikipedia for irrelevant information. I therefore feel we should change it to "Earth, the planet on which humans live". It's important that our information be as relevant as possible, and that is why we should change the first line.
I removed the word "billion" in the second most recent edit as of when this edit to the talk page was made, but then someone started to include both forms?? Any comments about whether the word "billion" should be kept?? 66.245.126.161 15:47, 9 Oct 2004 (UTC)
Billion re-inserted along with scientific notation for clarity (for those who understand sci. not.). Billion is also used in several other places within the article and I inserted sci. not. with them also. May have missed some. Also did some more cleanup on this hodge-podge article at the same time. I'm the someone referred to in your note. Who are you? - Vsmith 16:40, 9 Oct 2004 (UTC)
Earth is almost never called Sol III. Google hits:
The latter is almost exclusively science-fiction. It is not enough to be featured in the first line in the article about Earth. An obscure SF-term is not notable enough for that! Gerritholl 09:47, 16 Oct 2004 (UTC)
( SEWilco 05:54, 13 Apr 2005 (UTC))
Does anyone have any opinions about whether permanent human life outside earth can become possible?? Where in the universe is this?? (This question was brought to my attention based on something that Louis Epstein wrote a while ago about people living thousands of years, which he says advanced technology makes possible, but which can't become useful with human life staying completely on earth because earth will become too crowded.) (Also, if you have any external links that talk about doing so, feel free to include them.) 66.245.26.209 14:49, 23 Oct 2004 (UTC)
I've seen no mention of the number of artificial satellites orbiting Earth. I think it is definitely worth noting that our planet has thousands of bits of metal that we put up there ourselves orbiting it, even if only from an astronomical standpoint. -- Jacius 22:30, 24 Oct 2004 (UTC)
It would be good to link the various moon navigator's together, and provide a small page explaining them(it could be called Wikipedia:moon navigator). Right now, it's not obvious what purpose it serves. I don't have time to do it right now, but I'll do it if no one else gets to it. JesseW 13:39, 29 Oct 2004 (UTC)
The template seems to have been corrupted. I don't know how to access it so I copied the infobox from before the template move (11-4) and pasted it back into the article. - Vsmith 01:00, 14 Nov 2004 (UTC)
Rather large for an article don't you think?
http://commons.wikimedia.org/upload/f/f4/The_Earth_seen_from_Apollo_17.png
Zen Master 05:15, 19 Nov 2004 (UTC)
I've heard talk about a hollow Earth theory.. and I've done little research on it with Google. I'm not sure if it's complete bogus or if it's true, but some people seem to believe the theory (and some claim to have traveled inside Earth). Shouldn't something about this theory about Earth be included? -- Mike 07:43, 21 Nov 2004 (UTC)
![]() | This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 | Archive 2 | Archive 3 | Archive 4 | Archive 5 |
This is Archive 2 covering 2004.
How did the Earth form? What aspect of the Earth or its location do astrobiologists hypothesize as having been crucial to the development of its most idiosyncratic feature-- life. How did life emerge and when. Have there been any noteworthy biological events since the appearance of the first cell? How does the emergence and history of life relate to geological and climate evolution? How often is Earth hit by asteroids? What have been the consequences? Do we expect more?
How did scientists determine the average density of the earth? - The average density is Mass divided by Volume. To find the volume you need the radius which you can find by measuring the curvature of the Earth like Eratostenes did about 230BC. Then you know the volume of the Earth (assuming it is sufficiently spherical). To measure the mass you need to know the gravitational constant which was measured sometime I believe sometime in the 18th century. You apply Newton's law for gravity (the one with inverse-square radius) and you have the mass.
How many human-made satellites are there and when did the first one ( sputnik) go up? If you count every single piece of manmade debris - millions. Sputnik - October 4th 1957.
How do people study the Earth? What kind of scientists study it? What questions plague us, if any? What are predicted fates of the Earth? What about the ozone hole? What about the Kyoto protocol? What about geomagnetic reversals? 168... 05:22, 17 Jan 2004 (UTC)
Nearly all humans live on Earth: 6,327,152,352 inhabitants (November 1, 2003 est.)
User:Cantus has twice removed this statement from the intro paragraph: "the largest terrestrial planet in the solar system." I disagree with the reasons he's stated in the edit summaries (first that Jupiter's core might be larger, and then that it was "anecdotal"), and think it is a totally reasonable thing to say in the intro. Cantus, could you explain in greater detail why you think it should be removed? Bryan 04:27, 25 Mar 2004 (UTC)
I don't think there's any credible evidence of any terrestrial planet our solar system that is larger than earth. Cantus' objections are absurd. I say if it gets removed in the future, that should be considered vandalism unless there's a damn good explanation. -- Doradus 01:45, Sep 23, 2004 (UTC)
Bryan Derksen, where are you getting that mean temperature from? Averaging the min and max gives 258, not 282... If that average temp. was obtained thru a different method, care to mention the source? -- Cantus 06:00, 25 Mar 2004 (UTC)
the moon is not the only "natural satellite". E.g. the earth has captured an asteroid named Cruithne.
about mentioning the moon in a short article about earth: it's important. On this level, the earth is nothing than a planet among 9 others. The number of moons is characteristic and has to be meantioned.
I get 365.25636 / 365.2422 ≈ 1.00003877. Fredrik (talk) 19:25, 16 Jun 2004 (UTC)
The planet is big enough to have the core differentiated into a liquid outer core, which gives rise to a weak magnetic field due to the convection of its electrically conductive material, and a solid inner core.
It is generally believed that the rotation of the inner core (which is primarily composed of iron) creates the Earth's magnetic field. It is not known, exactly, why this occurs.
I think this is confusing. What is causing the magnetic field - inner or outer core? Are there two components of the field? This needs to be clarified. Paranoid 11:02, 23 Jun 2004 (UTC)
Does this need to be in this article? Do we even have a source for it? Edward 10:01, 25 Jun 2004 (UTC)
Inclination of Earth's orbit is given as 0.00005 degrees. Since this is the inclination to the Ecliptic, shouldn't this be 0 by definition? If the value given is related to some other plane, shouldn't that be made clear? Thanks. Amorim Parga 04:21, 17 Jul 2004 (UTC)
Shouldn't the entry say "Mostly harmless." ?? Just drooling. ;-)
Someone attempted to add a comparison of the torques felt on the Earth by different astronomical objects in order to explain why the moon has a stabalizing effect on the axis of the Earth. For one thing, this is rather technical information and might not fit very well into this page, but worse than that, the numbers quoted were simply very wrong. It is clear from the scale of the numbers stated that the author was merely comparing the force exerted on the Earth from various astronomical objects. However the force is not the same as the torque. The torque depends not on the total force but on the difference in the force applied to one side of the equatorial bulge rather than the other. Because it is so close, the moon has the largest gravitational gradient across the Earth of any astronomical object (followed shortly thereafter by the sun). Hence, the Moon exerts the largest torque on the Earth and that is why the moon acts to stabilizes the Earth's axial tilt.
However, other factors are also important. For example, relatively constant torques, such as from the Moon and Sun tend to cause axial precession and not nutations or axial tilts. For other planets (e.g. Mars) the total torques exerted depend more significantly on where it is in its orbit with respect to its nearest neighbors (e.g. Earth and Jupiter). It is when such time varying torques are a significant component of the total torque that one tends to promote chaotic shifts in the planet's axis.
Dragons flight 18:56, Sep 11, 2004 (UTC)
Seems that the complex and as stated controversial subject of chaotic instability of Earth's axial tilt under moon should be moved to another article, maybe to axial tilt, rather than in this long general article. - Vsmith 01:49, 17 Oct 2004 (UTC)
Cantus wrote: Encyclopedias are not written for aliens or animals. So what's wrong with aliens (or animals) reading Wikipedia? — Monedula 11:55, 12 Sep 2004 (UTC)
Can we remove the specific number and round to the nearest 10,000? I'm pretty sure we haven't been able to get even that accurate as it is. Oberiko 17:10, 17 Sep 2004 (UTC)
An anonymous user changed the surface area very slightly. I haven't done any calculations, but the change may even be within the error margin. However, I feared that this was one of the slashdot-inspired changes designed to evaluate the efficiency of Wikipedia peer review, so I'd like to find a recent supporting source for one of the numbers. However, my efforts of googling something up have been unsuccessful. Help? — David Remahl 20:32, 22 Sep 2004 (UTC)
I can contribute some calculations. Hopefully it's good enough to assume an oblate spheroid with polar radius 6356.78km and equatorial radius 6378.14km, which are taken from our own Earth page (but which are more precise than the values listed in NASA's planetary fact sheet).
First, the eccentricity is defined by:
Solving for eccentricity e:
Plugging into the formula for the area of an oblate spheroid:
This is evidently the calculation performed by the anonymous editor. However, carrying it to the nearest square kilometer is excessive, since (for instance) that implies that the radius figures are accurate to the nearest centimeter (!!), and is also far beyond the accuracy of the oblate spheroid approximation. Certainly 510,067,000km² is more than enough precision. -- Doradus 02:48, Sep 23, 2004 (UTC)
An unimportant point regarding the surface area of the Earth: the actual surface area of the Earth is slightly smaller than the surface area as calculated from its radius. This is due to the Earth's gravitational warping of space-time, and the difference is about an acre (about half a hectare).-- B.d.mills 11:06, 29 Oct 2004 (UTC)
I recently read a rather interesting article in Science News or in New Scientist about a theory that the Earth may have a Uranium core deep inside our Iron core. The main thesis of this theory is that it accounts for otherwise inexplicable levels of energy.
Unfortunately I don't have the citations at hand and I'd be reluctant to add references to this theory without some discussion of it's merits. (In any event it would be posed only as a short counterpoint paragraph to the comment about the core's putative lack of heavier elements, especially uranium.
Here's one older link: Discover, August, 2002. (Normally I wouldn't consider Discover to be a compellingly credible source --- but I'm sure I read this elsewhere and was impressed with the logic of the theory).
JimD 20:11, 2004 Sep 26 (UTC)
Where it says on the first line "Earth, the planet on which we live", that may be incorrect if aliens from another planet grasp satelite signals from our planet. In that case, we may offend them and they could sue Wikipedia for irrelevant information. I therefore feel we should change it to "Earth, the planet on which humans live". It's important that our information be as relevant as possible, and that is why we should change the first line.
I removed the word "billion" in the second most recent edit as of when this edit to the talk page was made, but then someone started to include both forms?? Any comments about whether the word "billion" should be kept?? 66.245.126.161 15:47, 9 Oct 2004 (UTC)
Billion re-inserted along with scientific notation for clarity (for those who understand sci. not.). Billion is also used in several other places within the article and I inserted sci. not. with them also. May have missed some. Also did some more cleanup on this hodge-podge article at the same time. I'm the someone referred to in your note. Who are you? - Vsmith 16:40, 9 Oct 2004 (UTC)
Earth is almost never called Sol III. Google hits:
The latter is almost exclusively science-fiction. It is not enough to be featured in the first line in the article about Earth. An obscure SF-term is not notable enough for that! Gerritholl 09:47, 16 Oct 2004 (UTC)
( SEWilco 05:54, 13 Apr 2005 (UTC))
Does anyone have any opinions about whether permanent human life outside earth can become possible?? Where in the universe is this?? (This question was brought to my attention based on something that Louis Epstein wrote a while ago about people living thousands of years, which he says advanced technology makes possible, but which can't become useful with human life staying completely on earth because earth will become too crowded.) (Also, if you have any external links that talk about doing so, feel free to include them.) 66.245.26.209 14:49, 23 Oct 2004 (UTC)
I've seen no mention of the number of artificial satellites orbiting Earth. I think it is definitely worth noting that our planet has thousands of bits of metal that we put up there ourselves orbiting it, even if only from an astronomical standpoint. -- Jacius 22:30, 24 Oct 2004 (UTC)
It would be good to link the various moon navigator's together, and provide a small page explaining them(it could be called Wikipedia:moon navigator). Right now, it's not obvious what purpose it serves. I don't have time to do it right now, but I'll do it if no one else gets to it. JesseW 13:39, 29 Oct 2004 (UTC)
The template seems to have been corrupted. I don't know how to access it so I copied the infobox from before the template move (11-4) and pasted it back into the article. - Vsmith 01:00, 14 Nov 2004 (UTC)
Rather large for an article don't you think?
http://commons.wikimedia.org/upload/f/f4/The_Earth_seen_from_Apollo_17.png
Zen Master 05:15, 19 Nov 2004 (UTC)
I've heard talk about a hollow Earth theory.. and I've done little research on it with Google. I'm not sure if it's complete bogus or if it's true, but some people seem to believe the theory (and some claim to have traveled inside Earth). Shouldn't something about this theory about Earth be included? -- Mike 07:43, 21 Nov 2004 (UTC)