Photos of the Sun

Asteroid Gaspra. Asteroids, Jupiter and Saturn

Asteroid Gaspra. Asteroids, Jupiter and Saturn

Some tens of thousands of rock fragments are called asteroids or small planets, whose dimensions vary from a rock to 1,000 km. diameter. About 95 percent of these bodies occupy a space between the orbits of Mars and Jupiter. Some groups orbit near the Sun, Mercury and others move away to Saturn's orbit.

The total mass of all asteroids in the Solar System is much smaller than that of the Moon. The larger bodies are more or less spherical, but those with diameters smaller than 160 km tend to have elongated and irregular shapes. Most, regardless of size, take 5 to 20 hours to complete a turn on its axis. Some asteroids have partners.

The asteroid Gaspra rotates in 7 hours, 3 minutes and counterclockwise when viewed from above the North Pole. Many craters are visible on the surface of Gaspra. Galileo's approach to the asteroid Gaspra marked the first encounter of a spaceship with an asteroid. Additionally, the meeting with Gaspra helped calibrate observations from Earth. Since all previous observations of asteroids had been limited to observation from Earth, the Galileo meeting provided a unique opportunity to increase our knowledge and update our models on how asteroids formed and evolved.

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Album: Photos of the Solar System Gallery: Asteroids, Jupiter and Saturn