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Our star lies in a swirling arm of the Galaxy, a region full of gas
and dust, which is home to some of the youngest and brightest stars. Our
position on the spiral gives us ‘a worm’s eye view’ of the Orion Arm, explain
Nigel Henbest and Heather Couper in The Guide to the Galaxy (Cambridge,
pp 265, £35/ $39.95 hbk, £17.95/ $24.95 pbk). On this personal
tour of our home Galaxy, the Milky Way, Henbest and Couper show how difficult
it has been to perceive the structure of the Galaxy that we live in. But
a quiet revolution has taken place because observation instruments can now
be placed above the Earth’s atmosphere. The use of radio waves, X-rays and
infrared, for example, has revealed the structure of the Galaxy, showing
it to be an active place where stars die and form. The map on the right
shows the dense dark molecular clouds and the young stars from Cygnus to
Orion, and it is one of many other excellent illustrations.