Canada will pay nearly $250 million over the next decade to help build the world's largest telescope.

The federal government will give up to $243.5 million over the next 10 years toward the Thirty Meter Telescope (TMT), Prime Minister Stephen Harper announced Monday. The TMT will be built in Hawaii, at the summit of the Mauna Kea volcano.

The telescope, which is expected to be operational in 2023-24, will cost an estimated $1.5 billion US.

Five countries are funding the project. The United States, Japan, India and China have all already committed funds towards its construction. The project was initiated by the University of California, the California Institute of Technology and the Association of Canadian Universities for Research in Astronomy. Observatories and institutions in China, India and Japan later signed on as partners.

Canada had promised to contribute $200 million toward the project years earlier. But the government stalled approving that funding, and the telescope's future was uncertain.

With the funds now approved, the government money will be spent in Canada, creating jobs in the telescope's construction and assembly, Harper said. The telescope was designed by Port Coquitlam, B.C.-based firm Dynamic Structures Ltd., which will also construct the device before shipping it to the Mauna Kea site.

Canada's investment will also secure a viewing share for Canadian researchers once the telescope is operational.

Canadian sources have already contributed $30 million to the project over the past several years. Most of the money came from the National Research Council and the Canada Foundation for Innovation.

Won't be world's largest for long

The telescope would be used to observe planets that orbit stars outside our own solar system and would enable astronomers to watch new planets and stars forming. It should help scientists see some 13 billion light years away for a glimpse into the early years of the universe.

The telescope's segmented primary mirror would be nearly 30 metres in diameter. The world's current largest optical telescope, the Gran Telescopio Canarias located on Spain's Canary Islands, is a 10.4-metre telescope with a segmented primary mirror.

Compared to smaller scopes, the TMT's large aperture will collect more light, allowing images of fainter objects. It will be able to reach further into the universe and see more clearly by a factor of 10 to 100 depending on the observation, according the project's website.

If built, however, the TMT isn't likely to hold the title for the world's largest telescope for long. A group of European countries plans to build the European Extremely Large Telescope, which will have a mirror that is 39 metres in diameter.

The E-ELT will be built atop a Chilean mountain, Cerro Armazones, in the country's Atacama Desert. Construction of the road and platform started early last year, according to the project's website. The earliest the telescope will be operational is 2024.

Opposition stages protests

Some Native Hawaiians oppose the TMT project because they believe it would defile a summit they consider sacred. Last week, 12 Native Hawaiians were arrested after trying to block the road leading to the mountain's summit during a protest.

CBC's As It Happens spoke with one of the protesters who was not arrested. More protesters were at the site the next day, she said. Native Hawaiians are not opposed to telescopes or astronomy, she said, but to them being built on their sacred mountain.

Environmentalists say the telescope would harm the rare wekiu bug.

The telescope will pay over $1 million a year for use of the land once it is fully functional, University of Hawaii at Hilo chancellor Donald Straney has said.

Eighty per cent of those funds will go to the Office of Mauna Kea Management, which preserves the natural, cultural and recreational resources of the mountain while providing a centre for astronomy, research and education.