It is high noon, again, for astronomers who want to erect a gigantic telescope on Mauna Kea, the grand volcano on the Big Island of Hawaii.

On June 21, the Supreme Court of Hawaii will hear oral arguments in Honolulu on whether to approve a building permit for the telescope, which would be the biggest and most expensive in the Northern Hemisphere.

This same court rescinded the telescope’s permit two-and-a-half years ago on procedural grounds, after protests had prevented construction on the mountaintop.

The Thirty Meter Telescope (named for the diameter of its main light-collecting mirror) has been 15 years in the planning. It would be one of three gargantuan telescopes now in the works that could transform astronomy in the 21st century.