The Hubble Space Telescope is celebrating its 15th year in space with two sharp, new views of famous stellar nurseries.
Since its launch on 24 April 1990, the observatory has taken more than 700,000 images of 22,000 objects. Among the most famous are the Whirlpool galaxy, whose spiral arms appear studded with rubies, and the Eagle Nebula, a giant region of gas and dust glowing with the light of newborn stars.
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But those celebrated images were taken before shuttle astronauts upgraded the telescope with a new instrument called the Advanced Camera for Surveys (ACS) in 2002. The ACS made the telescope 10 times more effective and expanded its wavelength range to span from the far ultraviolet to the infrared.
Now, to celebrate Hubble鈥檚 15th birthday, astronomers have unveiled new images of the two objects taken with the ACS. One represents a 鈥済rander view鈥� of the Whirlpool galaxy, showing a small galaxy that appears to lie on the tip of one of its spiral arms, says Mario Livio, a senior astronomer at the Space Telescope Science Institute (STScI) in Baltimore, Maryland, US.
The gravity of that companion galaxy pulls on its larger neighbour, producing disturbances that help make the spiral arms more pronounced, Livio says. The gas and dust in the arms form new stars that heat and ionise their surroundings, producing a red glow.
Pillars of creation
The second image shows a relatively unfamiliar section of the Eagle Nebula, which is better known for another set of finger-like columns of gas and dust dubbed the 鈥減illars of creation鈥�. This image reveals a single spire that stretches to 9.5 light years in length 鈥� twice the distance between the Sun and its nearest star.
The tower was carved by massive stars in the nebula 鈥� not visible in this image 鈥� which spew out high-energy radiation and winds of charged particles. 鈥淭he radiation and winds have managed to erode the less dense material, leaving behind only the densest cores that form these pillars,鈥� Livio told New 杏吧原创.
Inside the pillars, he says, stars are being born 鈥� fuelled partly by the stellar winds, which rage at thousands of kilometres per second. The winds form shock waves that compress the gas in the structures.
But the aesthetic of the image is what delights Livio. 鈥淭he first time I saw this I said, 鈥榃hoa, this is a Giacometti sculpture!'鈥� he recalls, referring to a Swiss artist known for his long, skinny sculptures. 鈥淚 find this striking 鈥� nature imitating art, or the other way around.鈥�
Controversial cancellation
Fans of Hubble may soon be able to celebrate the telescope鈥檚 future as well as its past. The telescope is expected to fail in 2007 or 2008, and NASA鈥檚 previous chief, Sean O鈥橩eefe, controversially cancelled all plans to repair it.
But his newly appointed successor, Mike Griffin, has said he will reconsider that decision after the first shuttle successfully returns to flight, a milestone now scheduled for 22 May.
鈥淚 am extremely encouraged by this,鈥� says Livio. 鈥淲e鈥檝e all been hoping Hubble would be serviced again. What Hubble has already achieved has gone way beyond my wildest expectations.鈥�
