Quote:
Originally posted by mika
No offense, but I felt like answering a challenging Trivial Pursuit question only to find out that the company who made that question didn't know the correct answer themselves.
http://www.astro.queensu.ca/~wiegert/3753/faq.html
The question itself (about that asteroid) was interesting, though :thumbsup
|
Dude, you're criticizing me, and patting me on the back at the same time. :1orglaugh
When I made the post, I read that this moon was categorized as a moon. Is it now? According to your article... no. Take a look at this:
http://www.space.com/scienceastronom...on_991029.html
To quote a bit of this:
Quote:
"Eventually these same channels provide the moons with escape routes. So the main difference between the moon (we?ve always known) and ?the new moons? is that the latter are temporary -- they come and go, but they stay for a very long time before they leave."
|
Quote:
"A moon typically is defined as an object whose orbit encompasses a planet, say, the Earth, rather than the sun, said Carl Murray, who worked with Namouni and Christou on the research.
But it?s hard to say what a "true" moon is, he said.
In his view, there are three classes of moons ? large moons in near-circular orbits around a planet, having formed soon after the planet; smaller fragments that are the products of collisions; and outer, irregular moons in odd orbits, or captured asteroids like Cruithne. In the past year, astronomers have reported finding such objects around Uranus."
|
Quote:
"At some stage you have to consider the definition of ?moon,?" he said. "Is a dust particle orbiting the Earth a ?moon? of the Earth?"
|
- very interesting because, as I said before, there is no minimal size of a satellite.
Quote:
"As for Cruithne, Namouni said it?s not really a "moon" because it moves around the Earth at this time but may not forever. Earth is causing Cruithne?s present trajectory, but it could eventually escape.
So it?s not a moon of Earth, but it might become one."
|
It appears that they have to define "moon" more precisely than just "a natural satellite that orbits the earth. I guess this is ok; what they really have to define is "orbit"... if he object does not appear to "orbit" the planet, then it cannot be a moon. This object does not appear to, so it is not a moon. The Moon appears to, so it is a moon. The problem lies in that the gravity of all objects effect all others, so when does a 3 mass system (such as the Sun, Earth, and Moon) make a planet-moon system going around the sun, and when does it be just 2 objects orbiting the Sun (which appears to be the case with the Sun, Moon, and Cruithne.
And dude... I could not possibly know the "correct answer" if the party who defines the answer changes their mind.
Nevertheless, this is an interesting thing that not many people knew about... so I thought I'd bring it up. There is nothing wrong with enlightening some people with some information that they knew nothing about which is so close to home (astronomically, anyway). :)
Btw, isn't this cool:
http://a52.g.akamaitech.net/f/52/827...rogan_01,1.jpg
Showing a camera view in which the Earth and Sun remain fixed, it shows the moon. Notice that it flies around the Lagrange points of the Sun-Earth system... it would be impossible to categorize this 'moon' as a simple orbit around the Sun by itself when it is so tied to Earth's orbit (just as the many Trojan Asteroids orbit in the Lagrange points around Jupiter).
Definition:
Lagrange points: Lagrange Points mark positions where the gravitational pull of the two large masses precisely cancels the centripetal acceleration required to rotate with them.
http://www.physics.montana.edu/facul.../lagrange.html