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zarcyb
Radio Wave
United Kingdom
1 Posts |
 Posted - 02/20/2003 : 11:15:17
I've been looking all over the internet for information but I can't find any. What would happen if the moon exploded, and what would the effects on Earth be? What would be the causes of different magnitudes/locations of explosions on the moon? Any help would be great :) Thanks.
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ObsessiveMathsFreak
Infrared Wave
Burkina Faso (Upper Volta)
282 Posts |
 Posted - 02/20/2003 : 11:23:35
The earth would fly off into outer space.Seroiusly. Remember that the moon is spinning around the earth but the earth is also spinning around the moon. Think two people holding hands and spinning in a circle. One of them lets go. The other goes .... "wheeeeee...." .
"May the maths be with you"
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screwball
Radio Wave
USA
15 Posts |
Posted - 02/20/2003 : 17:10:40
or a better question is why or how would the moon explode?
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lbooda
Gamma Wave
USA
2030 Posts |
Posted - 02/20/2003 : 18:39:35
Green cheese cannot explode.http://www.quantumdream.net
Phase reality!
{^,^}
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Mentat
X-Ray Wave
USA
1269 Posts |
Posted - 02/20/2003 : 19:01:20
If the Earth somehow managed to stay in orbit, then we would get a temporary ring (it couldn't last very long (geologically) because we don't have shepherd moons to keep it in place). I also, think there would be a powerful affect on tides. BTW, the moon is supposed to be leaving Earth, at a constant rait (please correct me if I'm wrong about this), so it doesn't have to explode, in order for us to experience the affects of it's being gone. Welcome to the PFs, zarcyb  .
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BoulderHead
Gamma Wave
Canada
2364 Posts |
Posted - 02/20/2003 : 19:08:36
quote:
BTW, the moon is supposed to be leaving Earth, at a constant rait (please correct me if I'm wrong about this), so it doesn't have to explode, in order for us to experience the affects of it's being gone.
I don't think I can wait long enough to experience that. I say we blow that piece of green cheese! 
The moon does a pulling manuever on the oceans, it it were gone I'd guess there would be alot less tidal action taking place. I've forgotten how the rotation of the Earth acts upon the water. Perhaps someone knows?
Conservative, n. A statesman who is enamored of existing evils, as distinguished from the liberal, who wishes to replace them with others.
-- Ambrose Bierce
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FZ
Gamma Wave
United Kingdom
2222 Posts |
Posted - 02/20/2003 : 21:22:37
By explode, do you mean literally explode or just disappear?If the moon explodes literally, a lot of earth would be bombarded by little bits of moon rock and the dust cloud would have a nuclear winter effect. Then again, it might cancel out global warming.  But if the moon just disappears, we will lose the lunar tides more or less instantly. We would also see widespread ecological issues with nocturnal creatures. It might have a bad effect on the earth's orbit, but I think this should stabilise eventually. Until it does, we should see quite some changes of climate. I think the mass of the earth is large compared to the moon enough not to make us go into space. (BTW, the leaving of the moon by tidal friction should take billions of years. Don't worry about it) Why would the moon explode? Dunno. Maybe renewed volcanic activity? But that shouldn't do much. Human action? I don't think we have the firepower yet. A major asteroid collision? Must be VERY big.... -------------
"....this will be one battle we will regret. Mark my words..."
FZ 11/14/2002
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Kerr_plunk
Micro Wave
USA
127 Posts |
Posted - 02/20/2003 : 21:40:34
quote:
BTW, the moon is supposed to be leaving Earth, at a constant rait (please correct me if I'm wrong about this), so it doesn't have to explode, in order for us to experience the affects of it's being gone.
If I remember correctly, there will be a point someday when the the earth and moon fall into synchronous rotation and the moon will stop moving away from the earth. Don't know how far it will be when that happens, though.
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Janus
PF Mentor
USA
1086 Posts |
Posted - 02/21/2003 : 00:51:12
quote:
Originally posted by FZ:
By explode, do you mean literally explode or just disappear?If the moon explodes literally, a lot of earth would be bombarded by little bits of moon rock and the dust cloud would have a nuclear winter effect. Then again, it might cancel out global warming.
This depends upon the size of explosion. If the velocity of the particles left after they overcome their own mutual gravitational attraction is much less than 1 km/sec, they won't overcome the Moon's own orbital velocity enough to fall into a low enough orbit to hit the Earth. quote:
But if the moon just disappears,... It might have a bad effect on the earth's orbit, but I think this should stabilise eventually. Until it does, we should see quite some changes of climate. I think the mass of the earth is large compared to the moon enough not to make us go into space. (BTW, the leaving of the moon by tidal friction should take billions of years. Don't worry about it)
Actually, the effect on the Earth's orbit would be very small. The Earth and Moon orbit around their common center of gravity which lies a little below the Earth's surface. This means that the Earth's center of gravity moves in a little circle of about 40,000 km, and takes around 28 days to do so. This amounts to a speed of about 16 meters/sec. It is this speed that would be combined with the Earth's orbital speed (30 km/sec) to determine the new orbit. This would produce a change in Earth's orbit of no more than 320,000 km. (compared to the 4 million km it already varies over the course of a year due to its orbital eccentricity, and which we don't notice) Exactly what effect it has will depend upon where the Earth is in its orbit and the Moon is in its. If the moon was on the Sunward side while the Earth was at Perihelion, the effect would be to increase the distance of Aphelion. If the Earth was at Aphelion and the moon at the same position, the result would be to increase the distance of Perhelion (decreasing the eccentricity of the Orbit.) Conversely, with the moon on the outward side of the Earth, the effects would be to reduce Aphelion and reduce Perhelion respectively. But in any case, the amount of change would be too small to make any real difference. Janus "Haec immatura a me iam frustra leguntur. o y"
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Phobos
PF Mentor
USA
1417 Posts |
Posted - 02/21/2003 : 14:37:06
humorous and informative additional information....
http://www.straightdope.com/columns/001027.html--------------------------
In the fabric of space and in the nature of matter, as in a great work of art, there is, written small, the artists signature. (from Sagan's "Contact")
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voyeur
Visible Light Wave
USA
577 Posts |
Posted - 02/22/2003 : 04:55:23
From what I seem to recall the lack of tides would be very bad but I can't remember why. We would also lose a radiation shield and meteor shield. I also recall that the moon will slip away, not stabilize. I don't claim to be absolutely certain of this stuff being true, but I have heard it somewhere.The moon is made of blue cheese, not green, hence the term 'once in a blue moon'
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FZ
Gamma Wave
United Kingdom
2222 Posts |
Posted - 02/22/2003 : 20:05:26
quote:
I also recall that the moon will slip away, not stabilize. I don't claim to be absolutely certain of this stuff being true, but I have heard it somewhere.
That's not right. The reason the moon is receding is because the lunar orbit is of a much lower frequence than the rotation of the earth. So we have friction in terms of tides, which slowly increases the angular velocity of the moon. This increases the radius of the orbit. Once the length of a month equals a day, and we are tidally locked, it should stop receding and the orbit should stabilise.-------------
"....this will be one battle we will regret. Mark my words..."
FZ 11/14/2002
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J-Man
Visible Light Wave
USA
744 Posts |
Posted - 02/24/2003 : 22:27:07
There was a special on either Discovery Channel, The Learning Channel, or Discovery Science Channel about this back in October 2002.
Apparently the moon plays a much greater role in environmental stability than simply the tides. I don't recall all the specifics, but if we had no moon the results would probably be devestating to all life on the planet.You might find info on Discovery or TLC websites.
This message was written entirely with recycled electrons.
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russ_watters
Radio Wave
USA
53 Posts |
Posted - 02/26/2003 : 16:05:29
quote:
The reason the moon is receding is because the lunar orbit is of a much lower frequence than the rotation of the earth. So we have friction in terms of tides, which slowly increases the angular velocity of the moon. This increases the radius of the orbit. Once the length of a month equals a day, and we are tidally locked, it should stop receding and the orbit should stabilise.
How can tidal friction increase the angular velocity of the moon? Tidal friction is decreasing the rotation rate of the earth, but the biproduct of friction is HEAT. There isn't any energy being transferred to the moon (at least not anymore since the rotation rate has been slowed to equal the orbital period). Also, doesn't angular velocity doesn't DECREASE as an orbit gets larger? The distance it has to travel at the same linear speed is larger, therefore the orbital period (and angular rate) are lower. It is my understanding that the moon is pulling away simply because its LINEAR velocity is too high: its above escape velocity. And since the moon is not rotating (or rather is rotating at a rate equal to its orbital period) and has nothing moving on its surface, there is nothing to absorb the extra energy and keep it from escaping.
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FZ
Gamma Wave
United Kingdom
2222 Posts |
Posted - 02/26/2003 : 18:50:20
quote:
How can tidal friction increase the angular velocity of the moon? Tidal friction is decreasing the rotation rate of the earth, but the biproduct of friction is HEAT. There isn't any energy being transferred to the moon (at least not anymore since the rotation rate has been slowed to equal the orbital period).
Hmm... I meant angular momentum...
This is due to the conservation of angular momentum. Angular momentum being equal to mvr, where m is the mass, v is the velocity (not angular velocity) and r is the radius of the orbit. This law states that in any system of rotating bodies, the total angular momentum of the objects remain constant. Applied to the earth moon system, the result is that any decrease in the angular momentum of the earth must increase the angular momentum of the moon.
quote:
Also, doesn't angular velocity doesn't DECREASE as an orbit gets larger? The distance it has to travel at the same linear speed is larger, therefore the orbital period (and angular rate) are lower.
Here comes the clever bit. If we combine the gravitational force equation and the centripetal acceleration equation, we have GMm/r^2 = mv^2/r
which simplifies to GM/r = v^2
Now, if we factor in angular momentum (mvr) , we will derive:
r = I^2/GMm^2 and v = GMm/I
This shows that an increase in angular momentum of the moon must mathematically result in an increase of the radius of the orbit and the linear velocity of the moon.-------------
"....this will be one battle we will regret. Mark my words..."
FZ 11/14/2002
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lbooda
Gamma Wave
USA
2030 Posts |
Posted - 02/26/2003 : 19:44:39
What would happen if the moon instead collapsed to a black hole?http://www.quantumdream.net
Phase reality!
{^,^}
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njorl
Visible Light Wave
USA
725 Posts |
Posted - 02/26/2003 : 20:03:37
What if it moved into the seventh house, and Jupiter aligned with Mars?Njorl "Deceive everyone under 30!" -- um, Me
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lbooda
Gamma Wave
USA
2030 Posts |
Posted - 02/26/2003 : 21:17:14
Then peace would guide the planets, and love would steer the stars.http://www.quantumdream.net
Phase reality!
{^,^}
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Mentat
X-Ray Wave
USA
1269 Posts |
Posted - 02/26/2003 : 21:18:08
quote:
Originally posted by lbooda:
What would happen if the moon instead collapsed to a black hole?http://www.quantumdream.net
Phase reality!
{^,^}
Is this possible?
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lbooda
Gamma Wave
USA
2030 Posts |
Posted - 02/26/2003 : 22:42:11
How about "were collapsed" rather then "collapsed."http://www.quantumdream.net
Phase reality!
{^,^}
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Ben-CS
Radio Wave
USA
46 Posts |
Posted - 02/26/2003 : 22:50:19
By itself, the moon could not collapse into a black hole. However, the moon could capture a small black hole and subsequently collapse (at a very slow rate) into that.All said, if the moon imploded, nothing particulary interesting would happen, save for the loss of moonlight and the occasional Einstein ring. We would still have tides and all. As long as our tiny dark satellite did not stray to close, it would pretty much be business as usual. Now, if the moon exploded, the side of Earth facing the moon would be hit by the initial blast. Part of the debris would remain in orbit. The debris orbiting within Earth's Roche limit would eventually fall to Earth in the ultimate meteor shower. The chunks that made it to the surface would cause the expected damage; the bits that did not make it to the surface would generate large amounts of dust. +++++++++++++++++ Extremes in politics are dangerous and should be avoided. Remaing neutral on all subjects is an extreme. +++++++++++++++++
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