How many stars are there in the sky?
” Under ideal conditions, an observer in the northern hemisphere can observe nearly 8000 stars with the naked eye. A few of these stars are very bright and are easy to see even through the glow of city lights. But most stars are faint and can only be seen under dark sky conditions away from city lights and with no moon in the sky. Thus, the number of stars that can be seen depends upon how faint one can see from a specific observing location. Suppose you wanted to know how many rain drops fall in your backyard in an hour during a rain storm. Clearly it is not practical to actually count all the individual drops. However, imagine that it is raining outside and you place a glass on the ground and count the number of raindrops that land in the glass each minute. If you know the (collecting) area of the glass and the area of your yard you can determine the number of drops that fall on your yard since raindrops in glass / raindrops on yard = collecting area of glass / area of yard or raindr
Like the number of grains of sand on the beach or angels that can dance on the head of a pin, the number of stars in the sky remains a great unknown. Discussing the number of stars in the Milky Way alone, astronomer William Keel, writing for the sci.astro Galaxies FAQ, claims that there are “about as many as the number of hamburgers sold by McDonald’s.” Then he elaborates. The usual way to determine the number of stars in the universe is to consider how many stars there are in the Milky Way, and then to multiply that number by our best guesstimate at the number of galaxies in the universe. This FAQ suggests there are probably about 400 billion stars in the Milky Way, although “a 50% error either way is quite plausible.” As for the number of
Ron H.J. Mathijssen Department of Medical Oncology, Erasmus MC – Daniel den Hoed Cancer Center, University Medical Center, Rotterdam, the Netherlands Howard Gurney Departments of Medical Oncology and Medicine, Westmead Hospital, University of Sydney, Westmead, Australia “Personalizing cancer care” is the theme of the 2009 ASCO Annual Meeting.1 This underscores the status of personalized medicine as a hot topic. However, in anticancer drug therapy for the individual patient, dose calculation remains an Achilles’ heel. How do we ensure every patient receives a drug dose high enough to be effective without causing serious morbidity? Pharmacogenetics has been touted as a potential answer. In this issue of Journal of Clinical Oncology, Innocenti et al2 provide a comprehensive assessment of the genes involved in irinotecan disposition. Irinotecan has a narrow therapeutic window, sometimes necessitating dose reduction and hospital admission for diarrhea and neutropenia.3 Several phase I and I
