However some properties have so far gone unexplained, like the Thebe Extension, which may be due to unseen bodies outside Thebe's orbit, and structures visible in the back-scattered light. One possible explanation of the Thebe Extension is influence of the electromagnetic forces from the Jovian magnetosphere. When the dust enters the shadow behind Jupiter, it loses its electrical charge fairly quickly. Since the small dust particles partially corotate with the planet, they will move outward during the shadow pass creating an outward extension of the Thebe gossamer ring. The same forces can explain a dip in the particle distribution and ring's brightness, which occurs between the orbits of Amalthea and Thebe. The peak in the brightness just inside of the Amalthea's orbit and, therefore, the vertical asymmetry the Amalthea gossamer ring may be due to the dust particles trapped at the leading (L4) and trailing (L5) Lagrange points of this moon. The particles may also follow horseshoe orbits between the Lagrangian points. The dust may be present at the leading and trailing Lagrange points of Thebe as well. This discovery implies that there are two particle populations in the gossamer rings: one slowly drifts in the direction of Jupiter as described above, while another remains near a source moon trapped in 1:1 resonance with it. Himalia ring In September 2006, as NASA's New Horizons mission to Pluto approached Jupiter for a gravity assist, it photographed what appeared to be a faint, previously unknown planetary ring or ring arc, parallel with and slightly inside the orbit of the irregular satellite Himalia. The amount of material in the part of the ring or arc imaged by New Horizons was at least 0.04 km3, assuming it had the same albedo as Himalia. If the ring (arc) is debris from Himalia, it must have formed quite recently, given the century-scale precession of the Himalian orbit. It is possible that the ring could be debris from the impact of a very small undiscovered moon into Himalia, suggesting that Jupiter might continue to gain and lose small moons through collisions. Exploration The existence of the Jovian rings was inferred from observations of the planetary radiation belts by Pioneer 11 spacecraft in 1975. In 1979 the Voyager 1 spacecraft obtained a single overexposed image of the ring system. More extensive imaging was conducted by Voyager 2 in the same year, which allowed rough determination of the ring's