Astronomer Masanori Iye of the National Observatory of Japan blames the blurry appearance of meteor trails at about 100 kilometers altitude on the fact that they were photographed with telescopes focused at infinity (“Out-of-focus find,” SN: 9/29/07, p. 205). But optics teaches that any object much farther away than the focal length of the telescope is essentially “at infinity.” Wouldn’t a routine cause of fuzzy telescopic images—diffraction—be a more important reason for the blurred trails?
For the telescope used in these observations, calculations indicate that improper focus causes much more blurriness than diffraction does, says Iye.—S. Perkins
Treating the symptoms
Subscribe to Science News
Get great science journalism, from the most trusted source, delivered to your doorstep.
“Stimulant Inaction: ADHD drug’s lift proves surprisingly weak” (SN: 11/3/07, p. 277) suggests that Ritalin fails to “cure” attention-deficit hyperactivity disorder. Ritalin for ADHD is like glasses for a vision problem. True, it aids some functions and not others—visual memory, not executive function, for example. But for the right child at the right time, Ritalin can be tremendously helpful, especially combined with other support the child needs.
Helen F. Neville
Who don’t you love?
“Tortoise Genes and Island Beings” (SN: 11/10/07, p. 298) refers to Lonesome George, the Galápagos tortoise, as “misanthropic”—meaning a hater of people. He certainly has good reason to dislike humans, but I wonder how the investigators could tell. Or did you mean that George doesn’t like other tortoises, and is therefore antisocial?
Lonesome George’s lack of gregariousness extends across species: He has shown next to no interest in other tortoises, and retreats to the far reaches of his enclosure when tourists and other strangers come to gawk.—B. Nelson