Fiery dust from an icy comet.When a space probe collected samples of dust from a comet, it returned to Earth with some surprises. Even though comets Non-periodic comets are seen only once. They are usually on near-parabolic orbits that will not return to the vicinity of the Sun for thousands of years, if ever. Periodic comets usually have elongated elliptical orbits, and usually return to the vicinity of the Sun after a number are frozen balls of ice and dust, the dust samples contained minerals that form only at high temperatures. In other words Adv. 1. in other words - otherwise stated; "in other words, we are broke" put differently , the comet somehow combined some of the hottest and coldest materials in the solar system solar system, the sun and the surrounding planets, natural satellites, dwarf planets, asteroids, meteoroids, and comets that are bound by its gravity. The sun is by far the most massive part of the solar system, containing almost 99.9% of the system's total mass. . The dust in question came from the comet Wild 2. In 2004, a spacecraft called Stardust star·dust n. 1. A dreamlike, romantic, or uncritical sense of well-being. 2. A cluster of stars too distant to be seen individually, resembling a dimly luminous cloud of dust. Not in scientific use. 3. swooped within 236 kilometers (147 miles) of the comet's core and collected grains of dust streaming off the object. Last January, a parachute parachute, umbrellalike device designed to retard the descent of a falling body by creating drag as it passes through the air. The development of modern aircraft has led to many experiments in the aerodynamic problems of parachute design, with the result that the delivered a canister of the material to the Utah desert (see "Capturing the Stuff of Space"). Researchers from the University of Washington in Seattle sliced a few of the tiny grains into hundreds of pieces. Their analyses revealed a crystal called olivine olivine (ŏlĭv`ēn), an iron-magnesium silicate mineral, (Mg,Fe)2SiO4, crystallizing in the orthorhombic system. , which forms at temperatures between 900 and 1,100 kelvins (1,160[degrees]F to 1,520[degrees]F). They also identified minerals that contain lots of titanium titanium (tītā`nēəm, tĭ–) [from Titan], metallic chemical element; symbol Ti; at. no. 22; at. wt. 47.88; m.p. 1,675°C;; b.p. 3,260°C;; sp. gr. 4.54 at 20°C;; valence +2, +3, or +4. and aluminum. These minerals only form at temperatures above 1,400 kelvins (2,060[degrees]F). Scientists have two possible explanations. One idea is that the dust particles formed at the center of the solar system when the sun was just a 10-million-year-old baby. The sun is now 4.6 billion years old. In those early days, a cloud of gas, dust, and ice surrounded the sun. That's where the planets formed. And, olivine and the other minerals could have formed in the steamy center as well. The sun's wind may have then pushed the particles to the chilly edges of the solar system, where they became part of newborn comets. The second theory proposes that the minerals formed near a different star that happened to be in the sun's neighborhood during the sun's youth. This star's wind could have then pushed the particles into our solar system. So, hot material from the nearby star may have been kicked into the territory of the comets. Scientists are now planning to test whether Wild 2's materials originally came from our solar system or from another star. The answer should help them explain how the comet developed such a hot-cold personality.--E. Sohn http://www.sciencenewsforkids.org/articles/20060329/Note3.asp From Science News for Kids March 29, 2006. Copyright [C] 2006 Science Service. All rights reserved. |
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