This chart based on data from NASA's Wide-field Infrared Survey Explorer illustrates how infrared is used to more accurately determine an asteroid's size; three asteroids of different sizes can look similar when viewed in visible-light.
Add image to your album
Email this page Post this page to your Facebook wall Tweet this page

How to Tell the Size of An Asteroid

This chart illustrates how infrared is used to more accurately determine an asteroid's size. As the top of the chart shows, three asteroids of different sizes can look similar when viewed in visible-light. This is because visible-light from the sun reflects off the surface of the rocks. The more reflective, or shiny, the object is (a feature called albedo), the more light it will reflect. Darker objects reflect little sunlight, so to a telescope from millions of miles away, a large dark asteroid can appear the same as a small, light one. In other words, the brightness of an asteroid viewed in visible light is the result of both its albedo and size.

The bottom half of the chart illustrates what an infrared telescope would see when viewing the same three asteroids. Because infrared detectors sense the heat of an object, which is more directly related to its size, the larger rock appears brighter. In this case, the brightness of the object is not strongly affected by its albedo, or how bright or dark its surface is. When visible and infrared measurements are combined, the albedos of asteroids can be more accurately calculated.

JPL manages the Wide-field Infrared Survey Explorer for NASA's Science Mission Directorate, Washington. The principal investigator, Edward Wright, is at UCLA. The mission was competitively selected under NASA's Explorers Program managed by the Goddard Space Flight Center, Greenbelt, Md. The science instrument was built by the Space Dynamics Laboratory, Logan, Utah, and the spacecraft was built by Ball Aerospace & Technologies Corp., Boulder, Colo. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.

More information is online at http://www.nasa.gov/wise and http://wise.astro.ucla.edu.

Image details

ID#:
PIA14733

Date added:
2011-09-29

Target:
Asteroid

Mission:
Wide-field Infrared Survey Explorer (WISE)

Spacecraft:
WISE

Instruments:
WISE Telescope

Size:
3450 x 2400 pixels (width x height)

Rating:



Views:
2,251

Full-Res TIFF:
PIA14733.tif (24.84 MB)

Full-Res JPG:
PIA14733.jpg (0.46 MB)

Image credit:
NASA/JPL-Caltech