Small Bodies

Ion Tail

The well-developed tail structure of Comet Halley was captured in this image taken March 5, 1986. At this point in its orbit, Halley had recently passed perihelion on February 9, 1986 and was at its most active. This 10-minute exposure was recorded at Mauna Kea Observatory on IIIa-J emulsion without filters. This image shows both the ion and dust tail, with the latter stretching for over 6 degrees on the sky.

Detachment Event

One of the more spectacular changes recorded for Halley during an apparition was the detachment event that happened April 12, 1986. This 3-minute exposure was taken using the Michigan Schmidt telescope at Cerro Tololo Interamerican Observatory. The resulting image clearly shows part of the ion tail structure detached from the comet. At this period, the orientation of the comet is such that the tail is foreshortened, with the prolonged radius vector pointing west of north.

Ray Structure

An example of the ray structure of Halley was captured on March 19, 1986, at the Mount Wilson/Las Campanas Observatories. This 10-minute exposure was recorded at the focus of the 100-inch telescope on Las Campanas in Chile. The close-up image, covering the inner 1 degree of the comet, shows a prolonged radius vector extending to the left.

Ida

This mosaic of the asteroid 243 Ida was acquired by the Galileo spacecraft just before the spacecraft made its close approach to the asteroid on August 28, 1993. Ida appears to be about 52 km (32 mi) in length and is irregularly shaped. This view shows numerous craters, including many degraded craters, indicating Ida's surface is older than previously thought. Galileo flew within about 2400 km (1500 mi) of Ida.

Chondrite Meteorite

This meteorite was collected from the Allan Hills in Antarctica. Meteorites are bits of rock that are captured by a planet's gravity and pulled to the surface. This meteorite is of a type named chondrite and is thought to have formed at the same time as the planets in the solar nebula, about 4.55 billion years ago.

Achondrite Meteorite

Discovered at Reckling Peak, Antarctica, this type of meteorite is known as an achondrite. It has a basaltic composition and was probably formed when an asteroid melted about 4.5 billion years ago. The asteroid broke up some time later and this small piece of the asteroid was captured by Earth's gravity and fell to the ground.

Iron Meteorite

This iron meteorite was found at Derrick Peak, Antarctica. This type of meteorite gets its name because it is mostly made of the elements iron and nickel. This sample is probably a small piece from the core of a large asteroid that broke apart.

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