On Mars, sunsets are blue.

 
Mars may be known as the Red Planet, but when it comes to sunsets, it's more of a case of the blues - or browns or grays, says a Texas A&M University researcher and veteran NASA camera operator on the distant planet.
Mark Lemmon, associate professor of atmospheric sciences and a camera operator on the twin rovers Spirit and Opportunity that have been on Mars since 2004, says sunsets on Mars are not quite the visual event as they are on Earth as recent NASA photos show. Sunsets on Mars are different from those on Earth. "We have known since the 1970s that Martian sunsets tend to be blue, but recent images vividly show Martian sunsets," Lemmon, who currently participates as one of the camera operators on the NASA project, says.
"The combination of dust particles and atmospheric conditions on Mars makes for some unusual sunset colors, but do not yield the spectacular sunsets we sometimes see on Earth.
"The blue color comes from the way Mars' dust scatters light. The blue light is scattered less, and so it stays near the sun in the sky, while red and green are all over the sky. On Earth, blue light is scattered all over by gas molecules, but there are not enough of these on Mars, which has less than 1 percent of Earth's atmosphere, to accomplish this."
Lemmon adds that Martian weather is hardly a picnic. Night time temperatures can frequently reach minus 90 degrees Celsius (-130 Fahrenheit). Reduced solar power in winter has restricted the operation of the twin rovers Spirit and Opportunity that landed on the planet seven years ago. Both far outlived their hoped-for six-month lifespan. Opportunity is still alive and working, but Spirit has not been heard from in nearly a year, Lemmon adds.
Atmospheric scientist Mark LemmonLemmon has been part of the NASA team that operates the rovers' robotic cameras while the rovers have transmitted almost 270,000 images back to Earth and given scientists a never-before-seen look at many Martian terrains and landscapes. He currently participates in the daily operations of the rovers as part of the Athena science team. The rovers are operated through the Jet Propulsion Lab in Pasadena , Calif.
Lemmon was awarded NASA's Public Service Medal for his work on another Mars mission, the Phoenix Lander , last year.
For a video link to a Martian sunset, go to http://www.youtube.com/watch?v=VIksHVxEH2c