Science News Roundup: Rare 'ring of fire' solar eclipse on the longest day of the year; Frigid dwarf planet Pluto may have started out its life as a hothead and more

An analysis of images of its surface taken in 2015 by NASA's New Horizons spacecraft and computer simulations of the dwarf planet's interior led the researchers to propose a "hot start" scenario for Pluto's formation some 4.5 billion years ago as the solar system, including Earth, took shape.

Following is a summary of current science news briefs.

Virgin Galactic, NASA to develop program for private missions to space station

Billionaire Richard Branson's Virgin Galactic Holdings Inc said on Monday it has signed up with NASA to develop a program to promote private missions to the International Space Station (ISS), sending the shares of the company up about 16%. As part of its agreement with the Johnson Space Center, the space tourism company will identify candidates interested in buying tickets for private rides to space in orbital-grade vehicles from other companies, and develop training packages under its "astronaut readiness program."

Rare 'ring of fire' solar eclipse on the longest day of the year

A shimmering ring of light flashed into view on Sunday in parts of the eastern hemisphere as the moon drifted across the face of the sun in a rare eclipse on the longest day of the year. The path of the eclipse spanned East Asia, South Asia, the Middle East, and Africa. Most locations saw only a partial eclipse, with just a handful witnessing the true "ring of fire".

China puts final satellite for Beidou network into orbit - state media

China on Tuesday successfully put into orbit the final satellite of its Beidou navigation network, a rival to the U.S.-owned GPS. The mission was originally set for June 16, but was canceled at the last minute due to technical problems detected during pre-launch tests of the Long March-3B carrier rocket.

Frigid dwarf planet Pluto may have started out its life as a hothead

Pluto, a frigid little world inhabiting the solar system's outer reaches, may have been born as a warmer place sheltering a subsurface ocean that still exists today, researchers said on Monday. An analysis of images of its surface taken in 2015 by NASA's New Horizons spacecraft and computer simulations of the dwarf planet's interior led the researchers to propose a "hot start" scenario for Pluto's formation some 4.5 billion years ago as the solar system, including Earth, took shape.

(With inputs from agencies.)