NASA’s Cassini Spacecraft Captures Another Pale Blue Dot, Uranus the Ice Giant

NASA's Cassini spacecraft captured images of the ice giant Uranus during its ongoing mission designed to study Saturn.

The Cassini spacecraft in its nearly decade long mission around the ringed planet has captured the first ever picture of the ice-giant Uranus that appears as a pale blue speck in the upper left of the picture released by the space agency, NASA.

In order to focus on the distant planet, the seventh planet from the Sun, the robotic spacecraft shifted its focus away from the target destination -the ringed planet on April 11, 2014.  When the planet was captured by the spacecraft's narrow-angle camera, Uranus, known to have the third-largest planetary radius, was on the opposite side of the sun as from Saturn. The view was obtained at a distance of 28.6 astronomical units from Cassini and Saturn.

"An astronomical unit is the average distance from Earth to the sun, equal to 93 million miles (150 million kilometers). At their closest - once during each Saturn orbit of nearly 30 years - the two planets approach to within about 10 astronomical units of each other,"NASA explains.

Uranus and Neptune are considered as sister planets and were discovered after the invention of the telescope. The two are at times referred to as 'ice giants' in order to differentiate them from the much larger planets namely Jupiter and Saturn, which are classic 'gas giants'. 

The signature name comes from the fact that in most parts the planet is composed of water, ammonia and methane, which are found in the frozen state of ice in the cold depths of the outer solar system. But Jupiter and Saturn have least percentage of ice as they are mostly made of hydrogen and helium. Methane is what gives the planet its blue color as it absorbs red wavelengths of incoming sunlight, but allows blue wavelengths to escape back into space.

This latest image captured by Cassini is an add on to the list of worlds captured by Cassini's camera, Universe Today reports.

The team working on Cassini's science investigation hopes that it will be able to use the image and spectra of the observation to help regulate its own instruments.