Astronomy's crown jewel — the Hubble Space Telescope — has turned 20, and retrospectives are definitely in order.
Since soaring skyward aboard the Space Shuttle Discovery on April 24, 1990, the orbiting observatory has amassed more than 930,000 observations and snapped some 570,000 images of 30,000 celestial objects. That's enough data — 45 terabytes — to fill nearly 5,800 DVD movies. Astronomers have published more than 8,700 scientific papers that utilize HST's data, about 650 last year alone.
NASA and the European Space Agency (the project's seldom-recognized partner) have pulled out all the stops in celebrating HST's 20th anniversary. For its part, NASA has launched multiple websites: one of them requires Adobe Flash player; a second recalls the mission's greatest hits; and a third is geared toward students and educators. For its part, ESA is sponsoring a Hubble pop-culture contest to gauge the extent to which HST and its science have become aspects of everyday life.
There's also a new effort to engage the public in "citizen science." The Space Telescope Science Institute (STScI), which has operated the observatory from the outset, has teamed with the Galaxy Zoo team so that you can try your hand at classifying galaxies by diving headlong into one of HST's deep-field images.
A feature article by astrophysicist Mario Livio recounts HST's greatest scientific achievements in Sky & Telescope's June 2010 issue.
To cap off the celebrations, astronomers have released stunning new views of a small bit of the Carina Nebula, seen here. They've named this scene the Mystic Mountain. Many news outlets have published only the visible-light view at left, but there's also an infrared composite, at right, that reveals a host of stars in and behind the dust-laced clouds.
Also on the site is a wide-field view of much more of the Carina Nebula, on which you can hunt out the Mystic Mountain. Three hints: it's small, it's upside down, and in's in a bright/dark transition zone.
Located about 6,500 light-years away, the Carina Nebula is a rich star-forming region dominated by the brilliant supermassive star Eta Carinae. Hubble's portraits show a 3-light-year-long bit that contains two jet-pairs of dense knots (Herbig-Haro objects) designated HH 901 and HH 902. The streams of knots are being squirted from the vicinity of new-forming stars embedded in two tower tips.
The cool, dust-laced towers themselves, mostly hydrogen and other gases, have been eroded out of the wall of the main nebula in a scene reminiscent of HST's iconic "Pillars of Creation" view of the Eagle Nebula (Messier 16), released in 1995. Intense ultraviolet emission from newborn stars is boiling off the gas in many places, compressing back sharp, illuminated rims and sculpting the whole thing beautifully.
Despite nearing retirement age, HST remains incredibly productive and in high demand. Since its fifth and final servicing mission last year, astronomers have clamored for roughly six times as much observing time as can be accommodated. With careful use and a little luck, the Hubble Space Telescope should still be going strong when its 25th anniversary rolls around in 2015.