The astronomical guard is changing as one pioneering space telescope begins to yield to a more-capable successor.
The European Space Agency (ESA) today released a "first light" image from its Herschel Space Observatory, shown above. The target is the Whirlpool Galaxy, some 31 million light years away in the constellation Canes Venatici. ESA launched Herschel (along with the agency's Planck spacecraft) May 14.
A quick scan of the two images shows why astronomers are excited about this new observatory. Herschel's vision is much sharper, thanks to a light-gathering mirror that's 3.5 meters (11.5 feet) cross.
Spitzer, launched in 2003, has been no slouch of an observatory, however. It's one of NASA's so-called "great observatories" on orbit, a roster that includes the Hubble Space Telescope, the Chandra X-Ray Observatory, and the Compton Gamma Ray Observatory.
For instance, Spitzer has helped astronomers study brown dwarfs -- stellar wannabies that never gained enough mass to trigger the powerful fusion reactions that ignite larger stars.
It's plumbed galaxies that give off most of their light in the infrared, a feature thought to be triggered by high rates of star formation within galaxies loaded with the cold gas and dust that form the basic building blocks for stars and planets.
It's conducted a survey of galaxies reaching back billions of years to help astronomers understand how galaxies have evolved.