When I arrived at Caltech in 1969 as an eager freshman, I remember admiring a series of color photographs — yes, actually in color — taken by the famous 200-inch Hale telescope on Mount Palomar. They were amazing for their day. I remember thinking that some anonymous astronomer had no doubt begrudgingly agreed to squander precious observing hours photographing a few celestial baubles for public-relations purposes.
How times have changed! Today a friendly competition exists among major observatories — most notably the Hubble Space Telescope and the powerhouse European Southern Observatory — to outdo each other's dramatic cosmic vistas.Exhibit A is an ESO image made public yesterday of NGC 1365, sometimes called the Great Barred Spiral Galaxy, about 60 million light-years away in the southern constellation Fornax. Just over a week ago, the Europeans released a view of this elegant pinwheel taken in visible light, and now they've followed up with a composite made through four different near-infrared filters.
Each view has its strengths. Visible wavelengths accentuate the dust lanes that drape along the long arms and seemingly extend all the way to the core. Crimson-colored patches of hydrogen-alpha emission pinpoint where bursts of star formation are ongoing. The infrared view cuts through much of the dust and gives a better feel for the bloated concentration of old stars that dominated the pronounced central bar.
Interestingly, since the 1990s astronomers have suspected that the bar might be a recent addition. In any case, it transitions to a pair of sweeping arms, bedecked with star-forming regions, that overall span some 200,000 light-years.Exhibit B, also released today, is a spectacular close-up of the Lagoon Nebula (cataloged both as Messier 8 and as NGC 6523) taken by the Hubble telescope's Advanced Camera for Surveys. The waves of fluorescing interstellar gas take on a strangely three-dimensional aspect in this 3-arcminute-wide view, the kind of turbulence that I wouldn't have imagined inside a lagoon (cosmic or otherwise).
The Lagoon is bright, large (1½° across), and a mere 4,000 to 5,000 light-years distant — easy pickin's for backyard telescopes of any aperture on these late-September evenings. It's too bad that our eyes can't detect this riot of color when we view this showpiece; through cruel evolutionary fate, our night vision renders such spectacles only in shades of gray. But we wouldn't see this in any case: even the mighty Hubble needed a hour's total exposure to get the three frames used in this composite.
There's no new science here — just some touristy snapshots to impress the friends and relatives back home. But if you want to know a little more, read up on NGC 1365 here and on the Lagoon Nebula here.