Motion of J002E3: Captured Object's Orbit Around Earth

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In summary, J002E3 is an object that was captured into a chaotic orbit around Earth, with the Sun to the left in animations created by Paul Chodas and Ron Baalke. Some astronomers prefer to use the term "object" instead of "moon" to describe it, while others argue about the definition of "planet" and "moon" due to various factors such as lack of atmosphere (not always a defining characteristic), history, and lack of standardization.
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Ivan Seeking
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The motion of J002E3, showing how the object was captured into its current chaotic orbit around the Earth. The Sun is to the left in these animations. Animations created by Paul Chodas and Ron Baalke.

http://neo.jpl.nasa.gov/j002e3.html [Broken]


So is this still being called a moon?

http://news.bbc.co.uk/2/hi/science/nature/2251386.stm
 
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  • #2
NASA seems to be content with "object". Some astronomers object to calling every satellite in the solar system a "moon". They want to reserve Moon as a proper name for THE Moon.
 
  • #3
The meaning of the word "planet" seems to be a little subjective as well. I once read that the biggest difference between a planet and a moon is that a moon has no atmosphere. Don't a number of "moons" have atmospheres; and doesn’t at least one planet, Pluto, lack any atmosphere?
 
  • #4
Astronomers still consider the Earth to have 1 moon, even though there are a couple curious nearby objects like J002E3. Note that last paragraph in the second link..."Earth's second one is called Cruithne. It was discovered in 1986 and it takes a convoluted horseshoe path around our planet as it is tossed about by the Earth's and the Moon's gravity. "

Originally posted by Ivan Seeking
The meaning of the word "planet" seems to be a little subjective as well. I once read that the biggest difference between a planet and a moon is that a moon has no atmosphere. Don't a number of "moons" have atmospheres; and doesn’t at least one planet, Pluto, lack any atmosphere?

Lots of gray areas in astronomical definitions like this.

You are correct that that "no atmosphere" is a bad definition of a moon, but maybe presented in a certain context it can get you close enough (e.g., if speaking in general to little kids or if you needed to take a guess on a game show :smile:)

Saturn's moon Titan has quite an interesting atmosphere (which NASA will be sending a probe into soon...yippee!). The planet Mercury has no real atmosphere except for the temporary particles the sun blasts off it. Pluto's* thin atmosphere disappears during its "winter" (it freezes and snows down to the surface). Asteroids don't have atmospheres but they are not moons (ok, a few are, like my namesake). Comets have gases surrouding their icy/rocky cores, but they are not planets.

In general, planets are the large, non-star objects orbiting a star. Moons are the things orbiting the planets. I would guess that Cruithne and J002E3 are not called moons because they're too odd (non standard orbits around the planet).

* keeping that particular debate of planet-hood (planet-dom?) aside
 
  • #5
Is this a situation where the definitions have been forced to evolve due to having better information about these various types of bodies?
 
  • #6
Originally posted by Ivan Seeking
Is this a situation where the definitions have been forced to evolve due to having better information about these various types of bodies?
That's part of the reason; others include nostalgia (a.k.a. history - look at the fuss about whether Pluto is a planet or not), stickiness (also a.k.a. history - 'moon' vs 'satellite'), and the lack of a linguistic dictator (even though the IAU does a pretty decent job of standarisation, not every editor of every relevant peer-reviewed scientific journal is always consistent).
 

1. What is J002E3 and what is its motion around Earth?

J002E3 is a mysterious object that was first discovered in 2002. It was initially thought to be an asteroid, but was later confirmed to be the upper stage of the Apollo 12 Saturn V rocket. Its motion around Earth is an elliptical orbit, with a period of approximately 3 years.

2. How was J002E3 captured by Earth's gravity?

J002E3 was captured by Earth's gravity due to a complex series of gravitational interactions with the Earth, Moon, and Sun. This resulted in the object being pulled into Earth's orbit and becoming a temporary satellite.

3. What is the current location of J002E3?

As of 2021, J002E3 is no longer in orbit around Earth. In 2003, it had a close encounter with Earth and was flung out of Earth's orbit, becoming a temporary satellite of the Sun. It is currently in a heliocentric orbit, meaning it orbits around the Sun.

4. How does the motion of J002E3 differ from other objects in Earth's orbit?

J002E3's motion is unique because it is not a natural satellite of Earth, but rather a human-made object that was captured by Earth's gravity. Its orbit is also highly elliptical compared to the relatively circular orbits of most satellites. Additionally, its orbital period is much longer than most satellites, which typically orbit Earth in a matter of hours or days.

5. What can we learn from studying the motion of J002E3?

Studying the motion of J002E3 can provide insights into the dynamics of objects in Earth's vicinity and the effects of gravitational interactions. It also serves as a reminder of the history of human space exploration and the impact of space debris on Earth's environment. Additionally, tracking and observing J002E3 can aid in further understanding its future trajectory and potential impact with other objects in the solar system.

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