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Solar system
Asteroid Ida

Ida was the second asteroid to be observed close-up by a spacecraft, when the Space Probe Galileo took pictures as it flew by on Aug 28, 1993. These pictures showed not only that Ida has a cratered surface, but also that it has a small moon, called Dactyl, which is about 1.6 x 1.2 km in diameter and orbiting 90 km away from the asteroid.


About the same age as the Sun: 4.5 billion years


Solar system, asteroid belt

Avg. distance from the Sun

429.15 million kilometers (266.66 million miles)


58 kilometers x 23 kilometers (or 36 mi x 14 mi)


4.2 x 1016 kilograms

Orbital period around the Sun

4.84 Earth years (1,768 Earth days)

Number of moons

1, named Dactyl

This image shows the cratered asteroid Ida. Ida's moon, Dactyl, is probably made from pieces that broke off Ida during an impact (Image courtesy of NASA).

Enlarge Image


"Fast Facts: Asteroid Ida" is a table that lists  the asteroid's age, location, average distance from the Sun, diameter, mass, orbital period around the Sun, number of moons, and distinguishing features. A picture of the asteroid is included.

Printer-friendly web page
Adaptable, at teacher's discretion
How to use in the classroom

Use this resource as:

A source of information. Read the table to find out about this object.

A large-number recognition activity. Have students review several solar system Fast Fact tables, including this one. Ask them to place the objects described in the Fast Fact tables in order, starting with the object closest to Earth and ending with the one farthest away. Students can arrange the Sun, planets, and asteroids from smallest to largest mass and/or diameter.

A compare/contrast activity. Have students review several Fast Facts tables for asteroids and comets. Students match the asteroids to statements that describe a unique feature of each asteroid, such as: This asteroid is the most geologically diverse, or this asteroid is a near-earth asteroid. Either the teacher or the students can generate the statements using information from the Fast Facts. Students also can create graphic organizers comparing the features of asteroids with those of comets.

An inquiry tool. Have students write down questions they would like answered about the image and the information in the Fast Facts table.

An engagement tool. Involve students in a discussion.

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