Rubin Planetarium Video - Minor Planets

Minor planets in our Solar System can be discovered by taking multiple images of the same star field and looking for objects that move between exposures. Generally, objects that are farther out in the Solar System, such as Trans-Neptunian Objects will move more slowly than objects nearby. We can determine the object's orbital parameters measuring its position in each image relative to background stars.

For centuries, astronomers have located minor planets throughout our Solar System by watching how these nearby neighbors move relative to background stars over the course of the night. LSST will provide unprecedented sky coverage that will accelerate the discovery and mapping of minor planets. The first asteroid Ceres, was discovered in 1801. Since then 800,000 asteroids have been discovered. It is estimated that LSST will discover about 5.5 million more. In fact, after the 10 years of LSST's survey there will be few asteroids larger than 140 meters left to discover. LSST will find nearly all of them.


  • Duration: 1:30 minutes
  • Format: 4k dome master PNG frame sequence, 2k preview in H.264
  • Audio: (none)



This animation focuses on determining the orbits of Trojan Asteroids in orbits near to Jupiter and trans-Neptunian Objects (TNOs) out past Neptune.


This animation shows two sets of images being taken by a telescope like LSST. Each set involves three images taken at different times of a given night.


If we assign each of the three images a different color - one red, one blue, and one green - and then combine them, stars (which are stationary relative to one another) appear as white objects and any objects that moved over the course of the three exposures will appear as red, green, and blue dots. Each dot corresponds to where the object was when each image was taken. Notice that the object to the east (left) moved a smaller angular distance during the three exposures than the object to the west (right). This relative motion is due to the fact that the two objects shown are at different distances from Earth and are moving at different speeds.


We are now going to leave Earth and hover over the Solar System to show you the orbital positions of Earth.


As the Earth moves around the Sun, we represent the timing of the images that were previously shown. Note that we have had to artificially increase the time intervals between actual exposures in order to better illustrate the relative orientation of the Earth and the two objects that we are measuring. Note that the angles for the Trojan on the right are larger than for the TNO on the left. This is because the Trojan is closer to Earth than the TNO.


In this final segment of the video, we show the orbits of the Trojan and TNO as determined by the position of each object relative to the background stars. You can see that Trojans are located in orbits around the Sun in the neighborhood of Jupiter, while TNOs have orbits out beyond Neptune. Astronomers use measurements of the positions of minor planets as they move in the sky to determine the orbits of these objects.

Additional References


Fiske Planetarium, University of Colorado Boulder

Data Sources: SkySkan; observations collected at Apache Point Observatory 3.5-m


Creative Commons Attribution 4.0 International License

Special Recognition

Data to Dome initiative


About the Video

Release date:April 10, 2023, 8:58 a.m.
Duration:01 m 44 s
Frame rate:30 fps

About the Object


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