Scientists have released the largest digital image of the sky ever made, mapping the Universe in more detail than any other image has ever achieved.
The international Sloan Digital Sky Survey-III (SDSS-III) collaboration is releasing the image free to all. It expects astronomers and ’citizen scientists’ will use it to make exciting new discoveries.
The composite image has been put together over the last decade from more than seven million 2.8 megapixel images, creating a colour image of more than a trillion pixels.
Prof Bob Nichol of Portsmouth University, the scientific spokesperson for SDSS-III, said: ’This image represents the culmination of more than a decade of work and opens opportunities for many years of scientific discoveries yet to come.’
The new image is at the heart of new data being released by the SDSS-III collaboration as part of the 217th American Astronomical Society meeting in Seattle. Along with previous data releases that it builds upon, it gives the most comprehensive view of the night sky ever made.
SDSS data has already been used to discover nearly half a billion astronomical objects, including asteroids, stars, galaxies and distant quasars. The latest, most precise positions, colours and shapes for all these objects have also been released this week.
Four scientists at Portsmouth University’s Institute of Cosmology and Gravitation are working on the SDSS-III project: Prof Nichol, Dr Claudia Maraston, Dr Will Percival and Dr Daniel Thomas.
Previous ambitious sky surveys, such as the Palomar Survey of the 1950s, are still being used as a reference and scientists expect the latest SDSS data to have a similarly long shelf life.
Using the new image, scientists will be able to measure distances to more than one million galaxies detected in it.
American astronomer Prof David Schlegel from Lawrence Berkeley National Laboratory in California said that measuring distances to galaxies is more time consuming than simply taking their picture, but in return, it provides a detailed three-dimensional map of the distribution of galaxies in space.
Schlegel is the lead investigator of the new SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), which aims to build the largest ever three-dimensional map of the Universe by 2014.
The goal of BOSS is to precisely measure how so-called ’dark energy’ has changed over the recent history of the Universe. These measurements will help astronomers understand the nature of this mysterious substance.
Schlegel said: ’Dark energy is the biggest conundrum facing science today and the SDSS continues to lead the way in trying to figure out what it is.’
SDSS-III is also undertaking two other surveys of our galaxy. The first, called MARVELS, will repeatedly measure spectra from approximately 8,500 nearby stars like our own Sun, looking for the tell-tale wobble caused by large Jupiter-like planets orbiting them.
MARVELS is predicted to discover hundreds of new large planets, as well as find a similar number of ’brown dwarfs’ that are intermediate between the most massive planets and the coolest stars.
The second survey, the APO Galactic Evolution Experiment (APOGEE), is using one of the largest infrared spectrographs ever built to undertake the first systematic study of stars in all parts of our galaxy, even stars on the far side of our galaxy beyond the central bulge.
Such stars are traditionally difficult to study as their visible light is obscured by large amounts of dust in the disk of our galaxy. However, by working at longer, infrared wavelengths, this experiment can study them in great detail, thus revealing their chemical composition and motions to explore how the different components of our galaxy were put together.