Amongst all the excitement over the first results from Herschel,
it’s easy to forget about its comparatively tiny American cousin
Spitzer. Launched in 2003 with its 3 instruments IRAC, IRS and
MIPS, Spitzer covers the infrared wavelengths from around 3 to
150 microns – a region that from Earth is either totally
inaccessible or severely hampered by atmospheric absorption.
With its 85-cm diameter primary mirror, it’s easy to dismiss
Spitzer as belonging to a former era. But new science is coming
out of Spitzer data every day, and vast quantities of data
remain unpublished in the archives. The big legacy surveys in
particular, such as c2d (Cores to Disks) and the galactic plane
surveys GLIMPSE and MIPSGAL, have released a wealth of data into
the public domain, throwing light on old problems and unveiling
new mysteries to solve. One interesting phenomenon witnessed on
the images from the GLIMPSE survey was a curious population on
extended green objects (EGOs). Catalogued by Cyganowski et al in
2008, these “green