Mars’ night atmosphere glows and pulsates in this data animation from MAVEN observations of spacecraft. Green-white false color shows the enhanced illumination of Mars’ ultraviolet ‘night glass’, measured by MAVEN’s Imaging UltraViolet Spectrograph at an altitude of about 70 miles (70 km). A simulated view of the Marsbol is added digitally for context, with ice caps visible at the wrist. Three night glass illuminations come about 1 rotation of Mars, the 1st much brighter than the other 2. All 3 bright appear shortly after sunset, appear on the left side of this view of the night side of the planet. The pulsations are caused by downward winds that increase a chemical reaction, producing nitric oxide which causes the glow. Months of data were averaged to identify these patterns, indicating that they recur at night.
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New images from NASA’s MAVEN spacecraft – released on August 6, 2020 – reveal large areas of the night sky of Mars pulsating in ultraviolet light.
The MAVEN mission team was surprised to find that the atmosphere pulsed exactly three times a night, and only in the spring and fall of Mars. The new data also revealed unexpected waves and spirals over the winter poles, while previous results from the Mars Express spacecraft also confirm that this night glass was clear over the winter pole regions.
This so-called ‘night glass’ would not be visible to an astronaut standing on Mars. This is because ultraviolet light – although detected by special instruments – is invisible to the human eye. Zac Milby, of the University of Colorado’s Laboratory for Atmospheric and Space Physics, said in a statement:
The ultraviolet glow usually comes from an altitude of about 70 kilometers (about 40 miles), with the brightest place about a thousand kilometers (about 600 miles), and is as bright in the ultraviolet as the northern lights of the earth. Unfortunately, the composition of Mars’ atmosphere means that these bright spots do not emit light at visible wavelengths that could be seen by future Mars astronauts. Pity: the light patches would intensify the air every night after sunset and float across the sky at 300 kilometers per hour (about 180 miles per hour).
This is an image of the ultraviolet ‘night glass’ in the Martian atmosphere. Green and white false colors represent the intensity of ultraviolet light, with white being the brightest. The image shows an intense illumination in the night atmosphere of Mars. The lights come regularly after sunset on Martian evenings in the fall and winter seasons, and disappear by midnight. Lightening is caused by increased descending winds which increase a chemical reaction, creating nitric oxide, which causes the glow. Image via NASA / MAVEN / Goddard Space Flight Center / CU / LASP.
The team found that the night glass of Mars appears to be brightest at the height of the planet’s northern and southern winters, when hot currents move away from the equator and to the pulse of Mars.
Nick Schneider of the University of Colorado is instrument lead for the MAVEN Imaging Ultraviolet Spectrograph (IUVS) instrument that made these observations, and lead author of a paper on this study published August 6, 2020, in the peer-reviewed Journal of Geophysical Research, Space Physics. Schneider said:
The images of MAVEN provide our first worldwide insight into atmospheric motions in the central atmosphere of Mars, a critical region where air currents carry gases between the lowest and highest layers.
The diagram explains the cause of Mars’ glowing night atmosphere. On the day of Mars, molecules are dragged apart by energetic solar photons. Global circulation patterns carry the atomic fragments to the nocturnal side, where downwinds increase the reaction rate for the atoms to reshape molecules. The declining winds occur in some seasons at the pulse before and in the equatorial regions at others. The new molecules have extra energy that they emit as ultraviolet light. Image via NASA / MAVEN / Goddard Space Flight Center / CU / LASP.
Scientists say the pulsations reveal the importance of undulating waves in the atmosphere of Mars. The number of waves and their speed indicate that the mid-atmosphere of Mars is influenced by the daily pattern of solar warming and disturbances of the topography of Mars’ enormous volcanic mountains. These pulsating spots are the clearest evidence that the waves of the middle atmosphere correspond to those known to dominate the layers above and below.
This is an image of the ultraviolet ‘night glass’ in the Martian atmosphere over the South Pole. Green and white false colors represent the intensity of ultraviolet light, with white being the brightest. The night glass was measured at an altitude of about 40 miles (70 km) by the Imaging UltraViolet Spectrograph instrument on NASA’s MAVEN spacecraft. A simulated view of the Marsbol is digitally added for context, and the faint white area in the center of the image is the polar ice cap. The image shows an unexpectedly bright glowing spiral in the night atmosphere of Mars. The cause of the spiral pattern is not known. Image via NASA / MAVEN / Goddard Space Flight Center / CU / LASP.
MAVEN mission scientists use the new images to help illuminate complex circulation patterns in the Martian sphere. Sonal Jain, also from the University of Colorado’s Atmospheric and Spatial Physics Laboratory, said:
MAVEN’s most important discoveries of atmospheric loss and climate change show the importance of these immense circulation patterns that transport atmospheric gases across the globe and from the surface to the edge of space.
Here’s more about the MAVEN mission:
Bottom line: New MAVEN mission images show large areas of Mars’ night sky glowing and pulsating with ultraviolet light.
Source: Imaging of Martingale Circulation Patterns and Atmospheric Times by MAVEN / IUVS Nightglow Observations
Via NASA
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