Earth Now Has a Trojan

Asteroid that is. I totally missed this yesterday but a loyal listener Dan brought it to my attention again. In a boing boing article Earth now joins an elite group of three other planets that are know to have Trojan companions. Trojans also share orbits with Neptune, Mars and Jupiter. Two of Saturn's moons share orbits with Trojans.

According to the Wiki article:

• ... the word trojan refers to a minor planet or natural satellite (moon) that shares an orbit with a larger planet or moon, but does not collide with it because it orbits around one of the two Lagrangian points of stability
• The Lagrangian points or L-points, are the five positions in an orbital configuration where a small object affected only by gravity can theoretically be stationary relative to two larger objects (such as a satellite with respect to the Earth and Moon).

It has been a long held belief that Earth has a Trojan companion, but until recently, none had been discovered.

Earth's Trojan asteroid was discovered by researcher’s using NASA’s Wide-field Infrared Survey Explorer project. From the article once more:

• The asteroid is roughly 1,000 feet in diameter (and) is about 50 million miles from Earth.

read complete Boing Boing article here

New Asteroids found in Neptune's Orbital "Dead Zones"

Here is some space trivia that I have always found fascinating. Every planet / sun combination has a few "weird" places in their orbits. These areas are for all intents gravity free zones. These places quite literally are gravity balanced places where the gravity attraction of the sun and the planet are canceled out. What is fascinating is there are not just one but five for every planet orbiting around the sun (and of course if there are moons, those too play into even more neutral areas) They exist several degrees ahead and behind the planet, 180 degrees or on the exact opposite side of the sun, between the sun and the planet and finally at a point out side the orbit of the planet where the planet and sun's gravity cancel each other out. These areas are called Lagrangian points or L points for short. The most studied are L4 just ahead of a planet and L5 behind, because they are the most stable.1 (L1 is between the planet and the sun, L2 is at the point outside the orbit with the sun & planet balancing and L3 is at 180 degrees)

L4 &5 ten to gather the most junk, but up to this point L4 & 5 points of Neptune's orbit have been very difficult to study as they are so very far away and Neptune's L5 is on direct line of sight with the bright center of our galaxy.

Scientist's have been persistent and with the recent blocking of the light from the galaxy center being blocked by dust have discovered a bonanza of large objects in Neptune's L5. These "Trojan" asteroids are about 100 kilometers in size and that there are about 150 Trojans of similar size. These Lagrangian points as so stable that these objects were most likely captured during the formation of our solar system.

What makes this discovery particularly noteworthy is best described by the article on IO9

• (the Trojan objects were likely captured)...before planets were brought onto a single orbital plane and Neptune itself revolved around the Sun in an orbit similar to that of the asteroids today. As the planets eventually locked into their current orbits, the asteroids were "frozen" in place at the points, but their eccentric orbits remained as evidence of a more chaotic time in the history of the solar system.

Now that is what I call cool stuff. Because up to this time I had assumed that there had always been a single orbital plane and the planets just cleaned up around them......Now we find that not only did some of the planets orbit off the plane but may have had non keplerian orbits to boot! Good stuff!

read complete IO9 article here