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Name: Marc S Willson
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Are there any recent articles on galactic evolution available via the internet? Also we would like to learn more about Alexander Wolszczan's discovery of the pulsar planetary system PSR1257+12. How far away is PSR1257+12 from our solar system? Why can we not see this system with the use of the Hubble telescope? How does radio astronomy detect "wobbles"? Is it possible to see the imaged data collected from the radio sky?

According to an article in the April 22,1994 Washington Post, the pulsar is located in the constellation Virgo at a distance of about 1200 light years. It is only about 12 miles in diameter and emits essentially no light, so there is no possibility of detecting it visually, even with the Hubble telescope. Pulsars are characterized by the extreme regularity of the radio wave pulses they generate. Wolszczan and his team detected slight irregu- larities in the timing of this pulsar's pulses; they hypothesized that this was the result of a wobble in the pulsar due to gravitational tugging by one or more nearby bodies. This hypothesis has received widespread acceptance. You may wish to look at the article in the April 22 issue of the journal Science for more information.

RC Winther

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