Rubin Planetarium Video - Jupiter Trojans

The Jupiter Trojans are asteroids that orbit the Sun at roughly the same distance and in the same direction as Jupiter. They are so named because of the Trojan War from Greek mythology. They are clustered around the L4 and L5 Lagrangian points, which are located 60° ahead and 60° behind Jupiter. These points are locations where an object can orbit the Sun at that distance without its orbit being disrupted by Jupiter. Jupiter Trojans located ahead of Jupiter (meaning they are leading Jupiter in its orbit) are known as the “Greek camp.” Those located behind Jupiter are in the “Trojan camp.” 65% of known trojans are in the Greek camp (leading group), while 35% are in the Trojan camp (trailing group). Other planets and even moons can have Trojan asteroids, but there are few. For example, there are 22 known Neptune Trojans. And Earth is known to have only one.

Currently, about 7000 Jupiter Trojans are known to exist. Over ten years of operation, it is expected that LSST will find nearly 300,000 more. By tracking the motions of the Jupiter Trojans, LSST will calculate the sizes and shapes of their orbits. LSST will also measure the brightness of each asteroid so that its size can be calculated (larger asteroids reflect more sunlight and therefore appear brighter.) And by measuring an asteroidʼs brightness in six filters, LSST will be able to determine its color and composition. The orbital parameters, size, and composition of all the Trojans will give astronomers information about the formation and history of the Solar System.


This journey starts close to a hypothetical Trojan asteroid. Pivoting around and pulling away from the Trojan establishes the 3D distribution of these objects with respect to the orbits of Jupiter and the other planets.


We begin orbiting around a Trojan asteroid, with the Sun and Milky Way visible in the distance. A distant population of other Trojans is visible in the distance, seen as a cloud of points projected against the stars. Note that the brightness of nearby asteroids has been greatly exaggerated to make them visible. If you were actually near a Trojan asteroid you would not be able to see the others with your eyes.


We pull away from the asteroid, and in so doing see the extended population of nearby Trojans. Again, their brightness has been exaggerated so they are visible here.


Pulling out of the ecliptic plane the orbits of the planets become visible, establishing the relative location of Trojan orbits. The two distinct populations of Trojans become visible on either side of Jupiter, at the L4 and L5 Lagrange points.


We shift our viewing angle back down into the plane of the Solar System, viewing the Trojans from the opposite side of the Sun from Jupiter. Settling down finally into the ecliptic plane, the vertical distribution of the Trojan family becomes apparent. Notice that the Trojans are not all in the same plane as the orbits of the planets.

Additional References


Caltech-IPAC/LSST Project/NSF/AURA

Special Recognition

Data to Dome initiative

About the Video

Release date:April 10, 2023, 8:43 a.m.
Duration:01 m 30 s
Frame rate:30 fps

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