Russian scientists on Saturday launched one of the world's biggest underwater space telescopes to peer deep into the universe from the pristine waters of Lake Baikal.

The deep underwater telescope, which has been under construction since 2015, is designed to observe neutrinos, the smallest particles currently known.

Dubbed Baikal-GVD, the telescope was submerged to a depth of 750-1,300 meters (2,500-4,300 feet), around four kilometres from the lake's shore.

Neutrinos are very hard to detect and water is an effective medium for doing so.

The floating observatory consists of strings with spherical glass and stainless steel modules attached to them.

On Saturday, scientists observed the modules being carefully lowered into the freezing waters through a rectangular hole in the ice.

"A neutrino telescope measuring half a cubic kilometre is situated right under our feet," Dmitry Naumov of the Joint Institute for Nuclear Research told AFP while standing on the lake's frozen surface.

Those who see Earth from the International Space Station often say it provides a new appreciation of our planet. The Avian Migration Aerial Surface Space project, or AMASS, takes advantage of thousands of images captured by astronauts to give people an appreciation of the migrations many birds undertake across the planet.

Also called Space for Birds, the project maps the routes taken by seven endangered or threatened bird species, highlighting along those routes habitat changes caused mainly by human activities. After more than four years, astronauts now have captured images of key locations along the migratory paths of all seven species. The Roberta Bondar Foundation sponsors AMASS in collaboration with NASA and the Canadian Space Agency (CSA). The foundation is a research and education effort started by Bondar, the first Canadian woman to fly in space.

The largest asteroid to pass by Earth this year will approach within some 1.25 million miles (two million kilometers) of our planet on March 21, NASA said Thursday.

The US space agency said it will allow astronomers to get a rare close look at an asteroid.

The asteroid, 2001 FO32, is estimated to be about 3,000 feet in diameter and was discovered 20 years ago, NASA said.

"We know the orbital path of 2001 FO32 around the Sun very accurately," said Paul Chodas, director of the Center for Near Earth Object Studies. "There is no chance the asteroid will get any closer to Earth than 1.25 million miles."

That is roughly 5.25 times the distance of the Earth from the Moon but still close enough for 2001 FO32 to be classified as a "potentially hazardous asteroid."

NASA said 2001 FO32 will pass by at about 77,000 miles per hour faster than the speed at which most asteroids encounter Earth.

"Currently, little is known about this object, so the very close encounter provides an outstanding opportunity to learn a great deal about this asteroid," said Lance Benner, principal scientist at NASA's Jet Propulsion Laboratory.