Posted on 12/21/2005 7:26:35 AM PST by John Semmens
DAMMIT!!!
OK. Try Again.
650,000,000KM six hundred and fifty million km. There.
Need more cofee
Almost had me believing this was real!
That article confirmed what I have been saying. Simply that Jupiter protects the inner planets.
I am just stating what I have read and what I have been taught.
Jupiter can only protect a small, very, very small area of the sky at a time. What protects the other huge area when it's not there and is somewhere else in the orbit. I don't think you understand the scope of the size of space we are talking about...
Jupiter is 778,330,000 km (5.20 AU) from the Sun. That is over 5 times the distance that we are from the Sun. To put that in scale, we are 149,600,000 km from the Sun. You mention Saturn... well, Saturn is 1,429,400,000 km (9.54 AU) from the Sun. AU mean Astronomical Units which = 149,597,870.691 km; the average distance from the Earth to the Sun. 1 AU is a long way -- at 100 miles per hour (160 kph) it would take over 100 years to go 1 AU.
That leaves a LOT of area that Jupiter cannot protect at any one time. It is no stretch to think that a rock the size of a small mountain could slip in across our path. It has happened on many occasions and several very recently.
Mike
Numbers to go along with your graphic. (the graphic does show Jupiter closer than it should BTW):
All planets move in ellipses. A planet that moves in a perfectly circular orbit is actually an ellipse with its eccentricity (e) = 0, a parabola has e = 1 and a hyperbola the e > 1. So the closer to zero the planets eccentricity, the more circular its orbit.
For the planets, the furthest point from the sun in its orbit is called aphelion and the closest is called perihelion.
All of the planetary distances from the Sun are measured in Astronomical Units (AUs). One AU is the average distance from the Earth to the Sun, which is approximately 93,000,000 miles.
Mercury: e = 0.2056 and its AU = .39
Venus: e = 0.0068 and its AU = .72
Earth: e = 0.0167 and its AU = 1
Mars: e = 0.0934 and its AU = 1.52
Jupiter: e = 0.0483 and its AU = 5.20
Saturn: e = 0.0560 and its AU = 9.54
Uranus: e = 0.0461 and its AU = 19.18
Neptune: e = 0.0097 and its AU = 30.06
Pluto: e = 0.2482 and its AU = 39.44
If you notice only two planets have a high eccentricity; Mercury and Pluto. Only one of them cross the mean distance of another planet from the Sun and that is Pluto and Neptune. Briefly Pluto is closer to the Sun than Neptune when its orbit is at perihelion.
The eccentricity of our planet's orbit is mild; aphelion and perihelion differ from the mean Sun-Earth distance by less than 2%. In fact, if you drew Earth's orbit on a sheet of paper it would be difficult to distinguish from a perfect circle and that is with e = 0.0167.
First, the asteroid belt has an estimated total combined mass of less than 1 tenth of the Earths moon. Second, Jupiter has a profound effect on the asteroid belt.
Since Jupiter has a semimajor axis of 5.2 AU (I AU is the distance from the Sun to the Earth) it ends up with an orbital period of 11.86 years. Since the asteroids are not all at the same distance from the sun, their orbital periods will differ in a direct relationship to their distance from the sun. This will result in some of them having an orbital period of one half of Jupiter. This puts those particular asteroids in a 2:1 orbital resonance with Jupiter. The result of this resonance is gaps called Kirkwoods gaps.
The rub is why did not this asteroid belt form a small planet? The reason is the gravitational force of Jupiter. It perturbs the asteroids giving them random velocities relative to each other.
Another effect of both Jupiter and the Sun on the asteroid belt is a group of asteroids that both precede and follow Jupiter in its orbit by 60 degrees. These asteroids are known as the Trojans.
The Planetary Report article from last summer, outlining the problem and explaining why we may need a mission to it in the next decade to determine if it is really a problem in time to prevent a disaster, is finally online here.
Impact Probability: 1.8e-03
0.180000000% chance of Earth impact or 1 in 556 chance or 99.82000000% chance the asteroid will miss the Earth |
Send some politicians in a spacecraft to the dangerous asteroid. They will ruin it before it hits our Mother Earth!!!
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