我觉得这个问题很有意思,我也想知道,就帮你找了一下:
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传统方法:
The traditional method of measuring distance is by noting the precise position of a star and then measuring its slight change in position when Earth itself has moved to the other side of the sun. This approach can also be used to find distance on Earth: If you carefully record the position of a tree an unknown distance away, move a specific distance to your side, and measure how far the tree has apparently "moved," then it's possible to calculate the actual distance to the tree by using trigonometry.
However, this procedure gives only a rough distance estimate to even the nearest stars, due to the gigantic distances involved and the subtle changes in stellar position that must be measured.
测量地球与其他天体间距离传统的方法是,首先精确地纪录恒星的位置参数,然后当地球绕到太阳另一面是测量该星体(对于观察者而言)位置参数的微小变化,再根据可能是一大堆的数学公式,计算出星体间的距离.我数学不好,可能哪位高手知道该怎样计算.这种方法同时也可以测量地球上两点间的距离:比如要测你和一棵树间的距离,先精确地纪录树的位置坐标,然后你自己移动一定的距离,根据树表观的位置变化量利用几何学知识就能测出你们间的距离了.
对于测量星体间的距离来说,这种方法显得十分粗糙,这里据说是新方法,但是废话太多我不翻译了,你自己看吧:
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The team's new measurement settles a controversy that arose when the European satellite Hipparcos provided a much shorter distance measurement to the Pleiades than expected and contradicted theoretical models of the life cycles of stars.
This contradiction was due to the physical laws of luminosity and its relationship to distance. A 100-watt light bulb one mile away looks exactly as bright as a 25- watt light bulb half a mile away. So to figure out the wattage of a distant light bulb, we have to know how far away it is. Similarly, to figure out the "wattage" (luminosity) of observed stars, we have to measure how far away they are. Theoretical models of the internal structure and nuclear reactions of stars of known mass also predict their luminosities. So the theory and measurements can be compared.
However, the Hipparcos data provided a distance lower than that assumed from the theoretical models, thereby suggesting either that the Hipparcos distance measurements themselves were off, or else that there was something wrong with the models of the life cycles of stars. The new results show that the Hipparcos data was in error, and that the models of stellar evolution are indeed sound.
The new results come from careful observation of the orbit of Atlas and its companion -- a binary relationship that wasn't conclusively demonstrated until 1974 and certainly was unknown to ancient watchers of the sky. Using data from the Mount Wilson stellar interferometer, next to the historic Mount Wilson Observatory, and the Palomar Testbed Interferometer at Caltech's Palomar Observatory near San Diego, the team determined a precise orbit of the binary.
Interferometry is an advanced technique that allows, among other things, for the "splitting" of two bodies so far away that they normally appear as a single blur, even in the biggest telescopes. Knowing the orbital period and combining it with orbital mechanics allowed the team to infer the distance between the two bodies, and with this information, to calculate the distance of the binary to Earth.
"For many months I had a hard time believing our distance estimate was 10 percent larger than that published by the Hipparcos team," said the lead author, Xiao Pei Pan of JPL. "Finally, after intensive rechecking, I became confident of our result."
Coauthor Shrinivas Kulkarni, a Caltech astronomy and planetary science professor, said, "Our distance estimate shows that all is well in the heavens. Stellar models used by astronomers are vindicated by our value."
"Interferometry is a young technique in astronomy and our result paves the way for wonderful returns from the Keck interferometer and the anticipated Space Interferometry Mission that is expected to be launched in 2009," said coauthor Michael Shao of JPL, prinicipal investigator for that planned mission, and for the Keck Interferometer, which links the two 10-meter telescopes at the Keck Observatory in Hawaii. The Palomar Testbed Interferometer was designed and built by a team of researchers from JPL led by Mark Colavita and Shao. It served as an engineering testbed for the Keck Interferometer.
Adapted from materials provided by NASA/Jet Propulsion Laboratory.