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Syzygy's Enlightenments
Developmental and Reproductive Toxicology Center of Expertise, Pfizer Global R&D, Eastern Point Rd, Groton, CT 06340
1 To whom correspondence should be addressed. E-mail: robert.e.chapin@pfizer.com.
Received May 17, 2007; accepted May 17, 2007
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An observer standing on the Earth and watching the moon pass directly in front of the sun experiences a syzygy (the perfect straight-line configuration of three heavenly bodies). Now imagine that observer standing at a telescope viewing two distant stars, one behind the other. How does she know the further star is there, particularly if it is smaller than the nearer? The only way is to change the point of observation (i.e., induce a little parallax). Only by changing one's perspective can one determine whether an observation is truly one point, or two different points overlaid atop each other.
One challenge for observational astronomers, or course, is that the dimensions of their systems (solar or galactic) often require changes that are larger than a laboratory or