THE STARS
The Globular Cluster
Messier 4, near Antares in
Scorpius; 7500 light-years
away. The image above right
was taken with the 0.9 m
telescope at Kitt Peak
National Observatory. The
central region of the cluster
is shown in the image (above
left) taken with the Antu
mirror of the VLT in 2003. The Crab Nebula, as
imaged by the Kueyen
mirror of the VLT in 1999.
The blue light is mainly
emitted by high-energy
electrons, which are ejected
by the neutron star at the
nebula’s centre. Green light
is produced by hydrogen.E152- 191 UNIVERSE UK 2003mb 7/4/03 5:51 pm Page 191