June 30 is Asteroid Day.

Asteroids, sometimes called minor planets, are rocky, airless remnants left over from the early formation of our solar system about 4.6 billion years ago. The current known asteroid count is 958,967.

This image was taken using the 200-inch Hale telescope on Palomar Mountain by astronomers at the Jet Propulsion Laboratory of the Deep Space 1 spacecraft at a distance of 2.3 million miles (3.7 million kilometers) from Earth. Tracing a path against the constellation Gemini. This image was obtained on Nov. 16, 1998, 23 days after the spacecraft’s launch from Cape Canaveral, FL.

The spacecraft was receding from Earth at a speed of 1.1 miles per second relative to Earth. The spacecraft, just 4.9 feet high, was 4 million times dimmer than the faintest star visible to the unaided eye.

Top of the image is north. Each side of this square image is five arc-minutes, or approximately 0.08 of one degree.

Deep Space 1 was the first mission under NASA’s New Millennium Program testing new technologies for use on future science missions. Among its 12 new technologies were a xenon ion propulsion system, autonomous navigation, a high-efficiency solar array and a miniature camera/spectrometer.

Visit NASA’s Asteroid Watch to learn more about how the agency tracks these celestial bodies.

Image Credit: NASA/JPL-Caltech