An unusual shower on September 1, 2007
Some time in the 40 years or so around 4 A.D., comet Kiess (C/1911 N1) passed by the Sun, ejecting a cloud of dust particles. The comet returned in 1911, after completing one orbit. The dust particles were pushed by the Sun's light into slightly wider orbits and have been returning ever since, forming a thin ongoing stream of dust that usually passes just outside Earth's orbit. On occasion, the combined gravity of the solar system's planets moves this dust trail into Earth's path. Earth encountered this 2000-year-old dust in 1935, 1986, and 1994, causing a meteor shower known as the Aurigids.
This very rare shower will occur again on 1 September 2007. A brief shower of tens of meteors will radiate from the constellation of Auriga, many as bright as the brighter stars in the sky. The Earth will be in the thick of it during the one hour centered on 04:33 a.m. PDT. The shower will be visible by the naked eye from locations in the western United States, including Hawaii and Alaska, from Mexico, and from the western provinces of Canada.
This unique encounter could provide insights about how long-period comets loose large dust grains and about how to translate the observed dust trail crossing into physical data about the parent comet, and even provide more evidence for the hypothesized "pristine crust" of a comet. This crust would be the product of cosmic ray bombardment during the years when the comet was in cold storage in the Oort cloud. |
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置顶卡
变色卡
千斤顶
显身卡
希望预报的不准，右下角为今年的
