アメリカ航空宇宙局（NASA）の火星無人探査車「キュリオシティー（Curiosity）」が初めてカラーで捉えた火星の夕陽の画像が、5月15日公開された。火星から見た夕日は、青みがかっていた。
夕陽は、キュリオシティーに搭載されたカメラで4月15日、ゲール・クレーター（Gale Crater）から撮影された。撮影の間、砂嵐の間で行われたが、一部の砂は空高く舞い上がっていたという。
火星では、大気中のちりに含まれる微粒子によって、他の波長の色よりも青い光を効率的に通す。青色の光が太陽周辺の空にとどまる一方で、黄色や赤色の光が広く拡散するため、青みがかって見えるという。
キュリオシティーは、画像をTwitterにも投稿している。
Curiosity: Mars Science Laboratory's Rover
Curiosity at Work on Mars (01 of17)
This artist\'s concept depicts the rover Curiosity, of NASA\'s Mars Science Laboratory mission, as it uses its Chemistry and Camera (ChemCam) instrument to investigate the composition of a rock surface. ChemCam fires laser pulses at a target and views the resulting spark with a telescope and spectrometers to identify chemical elements. The laser is actually in an invisible infrared wavelength, but is shown here as visible red light for purposes of illustration. (credit:NASA/JPL-Caltech)
Daybreak At Gale Crater(02 of17)
This computer-generated view depicts part of Mars at the boundary between darkness and daylight, with an area including Gale Crater beginning to catch morning light. (credit:NASA/JPL-Caltech)
Curiosity Launch Vehicle(03 of17)
The Atlas V 541 vehicle was selected for the Mars Science Laboratory mission because it has the right liftoff capability for the heavy weight requirements of the rover and its spacecraft. (credit:NASA/JPL-Caltech)
Mars Science Laboratory Spacecraft During Cruise(04 of17)
This is an artist\'s concept of NASA\'s Mars Science Laboratory spacecraft during its cruise phase between launch and final approach to Mars. The spacecraft includes a disc-shaped cruise stage (on the left) attached to the aeroshell. The spacecraft\'s rover (Curiosity) and descent stage are tucked inside the aeroshell. (credit:NASA/JPL-Caltech)
Curiosity Approaching Mars(05 of17)
The Curiosity rover is safely tucked inside the spacecraft\'s aeroshell. The mission\'s approach phase begins 45 minutes before the spacecraft enters the Martian atmosphere. It lasts until the spacecraft enters the atmosphere. (credit:NASA/JPL-Caltech)
Curiosity Inside Aeroshell(06 of17)
The Curiosity rover and the spacecraft\'s descent stage are safely tucked inside the aeroshell at this point. The aeroshell includes a heat shield (on the right, facing in the direction of travel through the atmosphere) and backshell. The diameter of the aeroshell is 14.8 feet (4.5 meters), the largest ever used for a mission to Mars. (credit:NASA/JPL-Caltech)
Mars Science Laboratory Guided Entry At Mars(07 of17)
The mission\'s entry, descent, and landing (EDL) phase begins when the spacecraft reaches the top of Martian atmosphere, about 81 miles (131 kilometers) above the surface of the Gale crater landing area, and ends with the rover safe and sound on the surface of Mars. During the approximately seven minutes of EDL, the spacecraft decelerates from a velocity of about 13,200 miles per hour (5,900 meters per second) at the top of the atmosphere, to stationary on the surface. (credit:NASA/JPL-Caltech)
Deceleration of Mars Science Laboratory in Martian Atmosphere(08 of17)
This artist\'s concept depicts the interaction of NASA\'s Mars Science Laboratory spacecraft with the upper atmosphere of Mars during the entry, descent and landing of the Curiosity rover onto the Martian surface. (credit:NASA/JPL-Caltech)
Mars Science Laboratory Parachute(09 of17)
This is an artist\'s concept of the Mars Science Laboratory Curiosity rover parachute system. (credit:NASA/JPL-Caltech)
Curiosity While On Parachute(10 of17)
This is an artist\'s concept of NASA\'s Curiosity rover tucked inside the Mars Science Laboratory spacecraft\'s backshell while the spacecraft is descending on a parachute toward Mars. The parachute is attached to the top of the backshell. In the scene depicted here, the spacecraft\'s heat shield has already been jettisoned. (credit:NASA/JPL-Caltech)
Curiosity And Descent Stage (11 of17)
This is an artist\'s concept of the rover and descent stage for NASA\'s Mars Science Laboratory spacecraft during the final minute before the rover, Curiosity, touches down on the surface of Mars. (credit:NASA/JPL-Caltech)
Curiosity's Sky Crane Maneuver(12 of17)
The entry, descent, and landing (EDL) phase of the Mars Science Laboratory mission begins when the spacecraft reaches the Martian atmosphere, about 81 miles (131 kilometers) above the surface of the Gale crater landing area, and ends with the rover Curiosity safe and sound on the surface of Mars. (credit:NASA/JPL-Caltech)
Curiosity Touching Down(13 of17)
This artist\'s concept depicts the moment that NASA\'s Curiosity rover touches down onto the Martian surface. (credit:NASA/JPL-Caltech)
A Moment After Curiosity's Touchdown(14 of17)
This artist\'s concept depicts the moment immediately after NASA\'s Curiosity rover touches down onto the Martian surface. (credit:NASA/JPL-Caltech)
Curiosity Mars Rover(15 of17)
This artist concept features NASA\'s Mars Science Laboratory Curiosity rover, a mobile robot for investigating Mars\' past or present ability to sustain microbial life. (credit:NASA/JPL-Caltech)
Curiosity's Close-Up(16 of17)
In this picture, the mast, or rover\'s \"head,\" rises to about 2.1 meters (6.9 feet) above ground level, about as tall as a basketball player. This mast supports two remote-sensing instruments: the Mast Camera, or \"eyes,\" for stereo color viewing of surrounding terrain and material collected by the arm; and, the ChemCam instrument, which is a laser that vaporizes material from rocks up to about 9 meters (30 feet) away and determines what elements the rocks are made of. (credit:NASA/JPL-Caltech)
Mars Rover Curiosity(17 of17)
This artist concept features NASA\'s Mars Science Laboratory Curiosity rover, a mobile robot for investigating Mars\' past or present ability to sustain microbial life. (credit:NASA/JPL-Caltech)
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