The largest ground-based astronomical project in existence, the Atacama Large Millimeter/ submillimeter Array (ALMA), is now open for scientists. Although construction is not complete, the first test images from ALMA have been released, revealing a spectacular look at star formation in two colliding galaxies.
ALMA detects radiation with wavelengths in the millimeter and submillimeter range, opening a window into the cold universe. Light at these wavelengths comes from gigantic cold clouds in interstellar space, where the temperature is just above absolute zero. Astronomers can use it to investigate astrochemistry, star and planet formation, and detect energy from the earliest and most distant galaxies in the universe.
These signals are easily absorbed by the water vapor in Earth's atmosphere, so telescopes hoping to detect them must be built on high, dry sites. This is why ALMA is located near San Pedro de Atacama in northern Chile, one of the driest places on earth.
The revolutionary design of the ALMA telescope is its 66 high-precision antennas that can be arranged in different configurations, with a maximum distance between antennas varying from 150 meters to 16 kilometers, giving the telescope a powerful "zoom." Only a third of these antennas are operating now, but the first published images show that ALMA will be able to probe the cold universe with unprecedented sensitivity and resolution. At full operation, in 2013, its vision will be up to ten times sharper than the Hubble Space Telescope.
The test images from ALMA show star formation in the colliding Antennae galaxies. Instruments that detect visible light, like the Hubble telescope, show the stars in the galaxies, but ALMA reveals even more: clouds of dense cold gas that serve as stellar nurseries, where new stars are born.
The ALMA project is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. Scientists from all over the world are submitting requests to use the telescope for their research. Soon, ALMA will be used to explore the enormous black hole at the center of the Milky Way and search for distant galaxies forming at the edge of the observable universe.
Thijs de Graauw, ALMA Director, said: "Today marks the recognition of the successful coalition of thousands of people from all over the world all working with the same goal: To build the world's most advanced radio telescope to see into the universe's coldest, darkest places, where galaxies and stars and perhaps the building blocks of life are created."