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Unformatted text preview: erse Astronomy - The Solar System Interplanetary Matter Near Earth Asteroid Rendezvous (NEAR) Closing in on Eros... 15 NATURE of the Universe Astronomy - The Solar System Properties of asteroids:
Surfaces are cratered. Interplanetary Matter Gaspra Spectra reveal the composition of asteroids: primarily made of rock (silicates, with varying amounts of carbon and other minerals) some asteroids also consist of metals (predominantly Iron-Nickel) Regolith on Eros Mass: some asteroids are double or have moons, which allows us to measure their mass, and hence their density.
Antiope Density: some are solid rock (higher density), while others are like "rubble piles" (low density)
16 NATURE of the Universe Astronomy - The Solar System What are comets? Interplanetary Matter 17 NATURE of the Universe Astronomy - The Solar System Interplanetary Matter In 1705, Edmond Halley concluded that the comets observed in 1456, 1531, 1607 and 1682 were one and the same. He predicted the next return of the comet for 1758. The comet returned in 1759, and is now called "Halley's comet". The last return of Halley's comet was in 1986. Historical records indicate that it has been observed every 75 to 77 years for at least the last 2,200 years. 18 NATURE of the Universe Astronomy - The Solar System How do comets "work"? Interplanetary Matter Fred Whipple in 1950 described comets as "dirty snowballs" - they are made of ice, dust, and some rocks. Main features: core (nucleus): <10 km across coma: up to 100,000 km tail: up to 1 Astronomic...
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