Resources: Worksheet, Image Files, MaxIm, Megastar

Terminology: AlbedoApparent MagnitudeOpposition

Tutorials: Importing Images into MaxImAligning and Animating ImagesFITS HeaderImage Calibration

Asteroids are rocky or metallic bodies that orbit the Sun and are generally smaller than most moons.  They are found throughout the Solar System, with a higher concentration between the orbits of Mars and Jupiter, and a likely much larger number past the orbit of Neptune. These objects are most likely remnants from the formation of the Solar System that were not absorbed by the large planets as they formed. Thus, a better term for these objects as a whole is "minor planets", while "asteroids" has come to refer specifically to the objects orbiting between Mars and Jupiter.

Inner Solar System

The physical composition of asteroids is varied and in most cases poorly understood. Ceres appears to be composed of a rocky core covered by an icy mantle, where Vesta is thought to have a nickel-iron core, olivine mantle, and basaltic crust. 10 Hygiea, however, which appears to have a uniformly primitive composition of carbonaceous chondrite, is thought to be the largest undifferentiated asteroid. Most of the smaller asteroids are thought to be piles of rubble held together loosely by gravity, though the largest are probably solid. Some asteroids have moons or are co-orbiting binaries: Rubble piles, moons, binaries, and scattered asteroid families are believed to be the results of collisions that disrupted a parent asteroid.

Albedo is a measure of the percentage of light that an object reflects. Specifically, the geometric albedo is a measure of the reflectivity of an object when the source of light is directly behind the observer - like when viewing an asteroid at opposition. Albedo is measured on a scale of zero to one, zero representing a surface that reflects no light, and one representing an object that reflects all incoming light. Asteroids typically have very low albedos, and many cannot be seen without the use of binoculars or a telescope.

Asteroid Belt

Learning Goals: The goal of this lab is for students to find and identify main belt asteroids using observations of the ecliptic, and to use the photometry tool in MaxIm to determine the rotational period of an asteroid.

Suggested Observations: Multiple long exposure images of the ecliptic near the antisolar point - This location is ideal for asteroid detection.

Challenge: Use astronomical images to find a (possibly as-yet-undiscovered) asteroid in a field of stars. In addition, determine the rotation period of an asteroid from a series of time-delay images.