European plans to build a massive optical telescope with a 100m mirror have been scaled back in favour of a 'scope with a mere 42m main reflector after the projected construction costs for the original dish reached €1.5bn.

However, the planned telescope is still bigger than the one planned by the US (30m), something scientists at the European Southern Observatory (ESO) admit has been a motivating factor.

The telescope will still be astonishingly powerful, giving astronomers a glimpse of distant planets. While a 100m telescope could have captured snapshots of alien continents, a 42m telescope will be more limited. It will, however, be able to analyse the atmospheres of exoplanets, identifying any telltale signs of life, such as chlorophyll.

Stargazers will also be able to peer back to the earliest years of the universe, and look at some of the galaxies that formed all those billions of years ago.

The ESO has a stonking track record when it comes to doing world class science. According to the BBC, an average of 1.5 academic papers is published every day based on observations from the 8.2m Very Large Telescope the organisation currently operates.

The ESO is considering a number of sites for the 'scope. South Africa, Tibet, Morocco, Greenland and Antarctica are all still on the table. If they manage to agree where to build it, construction could begin as early as 2010. ®