It is now a couple of weeks since the Herschel telescope reached the end of its operational life after exhausting its supply of liquid helium (needed to keep the instruments and detectors cold enough). Much has already been said about the scientific importance of Herschel, which gave us an unprecedented view of the infrared universe, and it is clear that the legacy will continue for some time as the observations and data it collected in its four years of operation are studied, analysed and revisited time and again to eek out every nuance of useful information.
However, I thought it was also worthwhile dwelling briefly on the educational impact of Herschel and other missions like it. Most of the major advances in the last 50 years in astronomy have, to a lesser or greater extent, only been possible due to the expansion of our telescopes into the non-visible part of the electromagnetic spectrum. From the discovery of pulsars and quasars with radio telescopes, through the discovery of the cosmic microwave background, to probing the inner regions of active galaxies with X-ray satellites, every part of the EM spectrum has been instrumental in one or more major advances. Nevertheless, it is sometimes difficult to bring this revolution to non-astronomers, especially in schools and with the general public.
Part of this problem is simply aesthetic. We are now accustomed to (though still mesmerised by) the astonishing visible-light images coming from the likes of the Hubble Space Telescope and ground-based telescopes equipped with modern digital cameras. However, the combination of resolution, field-of-view and colour that makes these images so stunning is hard to achieve in many other wavebands, and even where the perceived quality is comparable, the results often lack the sense of depth and scale that are hallmarks of a truly great astronomical image.
Herschel, however, fits neatly into a waveband that brings new information and excitement, but is close enough to the familiar optical universe that direct comparison is possible. An excellent example is the Horsehead Nebula. Perhaps one of the most recognisable of extra-solar objects, Herschel looks straight through the (optically) dark dust that gives the nebula its distinctive shape and allows us to explore the underlying star formation, but at the same time the image is recognisable a nebula and has the depth of structure that draws people to explore it, regardless of their prior interest in astronomy. This makes this, and many other examples from Herschel, ideal first steps in exploring importance of the electromagnetic spectrum to astronomy.
Therefore, as well as celebrating its importance to research, I will also be raising a glass to the help that Herschel will continue to give me and my colleagues in bringing the delights of the multi-wavelength universe to an unsuspecting public.
Images: Above, Herschel’s view of the Horsehead Nebula. Credit: ESA. Below, Hubble’s view of the Horsehead Nebula in near-infrared. Credit: NASA/ESA. Read more about the images.