18 19[18] Hot pixels (arrowed) are a form of static or predictable noise in an image. By taking
an exposure of a similar length with the telescope’s cover fitted, the resulting dark frame
image contains only static noise. Subtracting this from the original light frame removes
the static noise.
[19] Beta Pictoris b, the extrasolar planet can be seen as the white dot just outside the
central dark blue circle, above and to the left. The star Beta Pictoris itself lies at the centre
of the blue circle. The lobes are dust, and the image is captured at infrared wavelengths.
ESO, A.-M. Lagrange et al.
[20] Fomalhaut is a young star 25 light years away. In this composite image from the
Hubble Space Telescope, the star is at centre, and a planet about three times the size of
Jupiter has been identified orbiting Fomalhaut at a distance of 10.7 billion miles. Known as
Fomalhaut b, it is shown larger in the detail picture at bottom right. (NASA/ESA/University
of California, Berkely/JPL/Goddard/Lawrence Livermore Laboratory.)20Astronomer Book