The Extremely Large Telescope is currently under construction, with the most recent milestones including progress made with building the dome, central structure and the base for the primary mirror.

Construction of the world's largest telescope has reached its highest point with assembly of the roof's dome and large sliding doors that will shield the observatory. The European Southern Observatory ...

While both deal with space, planetariums and observatories are different. Observatories use telescopes to view the actual sky, while planetariums project simulations of the stars and planets.

Construction of the world's largest telescope moves forward with progress of the structure's dome and housing for the primary mirror. The European Southern Observatory's (ESO) Extremely Large ...