The National Aeronautics and Space Administration's Mars rover Curiosity has captured stunning images of the Sun setting on the red planet, showing blue hues of the serene sundown over the Martian horizon.
The sun dips to the Martian horizon in a blue-tinged sky in images sent home to Earth last week from Curiosity, the NASA said.
Curiosity used its Mast Camera (Mastcam) to record the sunset during an evening of sky-watching on April 15. The imaging was done between dust storms, but some dust remained suspended high in the atmosphere.
The sunset observations help researchers assess the vertical distribution of dust in the atmosphere. "The colours come from the fact that the very fine dust is the right size so that blue light penetrates the atmosphere slightly more efficiently," said Mark Lemmon of TexasA&MUniversity, the Curiosity science-team member who planned the observations.
"When the blue light scatters off the dust, it stays closer to the direction of the sun than light of other colours does.
The rest of the sky is yellow to orange, as yellow and red light scatter all over the sky instead of being absorbed or staying close to the Sun," said Lemmon.
Just as colours are made more dramatic in sunsets on the earth, Martian sunsets make the blue near the sun's part of the sky much more prominent, while normal daylight makes the rusty colour of the dust more prominent.
Since its August 2012 landing inside Mars' Gale Crater, Curiosity has been studying the planet's ancient and modern environments.