Motion of Itokawa
Spot the Asteroids!
Have you ever wondered what it is like to be a professional astronomer, searching through spacecraft data in search of new worlds? Well, here’s your chance to hunt for asteroids as astronomers do!
This short movie was shot by the Japanese AKARI space observatory. It shows the near-Earth asteroid Itokawa – the bright blob near the centre – as seen by AKARI’s infrared camera. The relative closeness of the asteroid to Earth is betrayed by its rapid motion over a period of 12 minutes. Its brightness is also linked to its infrared (heat) output. (Data such as this are used to give a better idea of the sizes of asteroids that might one day be found on a collision course with Earth.)
Itokawa is not the only piece of space rock in this movie. Also present are two much fainter asteroids that are slowly moving across the sky. One is orbiting in a similar direction to Itokawa. Have you got the patience and ability to find them? Note that stars appear to twinkle in the video. The images in this movie are raw, the kind astronomers themselves use for research. Many scratches and streaks caused by cosmic rays and other effects can clearly be seen.
When the movie was made on 26 July, Itokawa was in the constellation of Scorpius. The asteroid and Earth were then at their closest to each other, about 42 million km apart. (For comparison, Earth is 150 million km from the Sun.)