By Tom Mason
Office of Communications and Outreach Manager
Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado Boulder
On Sept. 11, 2018, at approximately 6 a.m. local time in eastern South America, NASA’s Global-scale Observations of the Limb and Disk, or GOLD, mission sent back its very first image.
Maps like this one enable researchers to determine global-scale temperature and composition at the dynamic region where Earth’s upper atmosphere meets space. The image shows ultraviolet light (135.6 nm) — a kind of light that’s invisible to the human eye — emitted by atomic oxygen present approximately 99 miles (160 km) above Earth’s surface. The colors in the image correspond to emission brightness: The strongest emissions are shown in red and the weakest in blue. Known as “airglow,” this light is produced by oxygen as it transitions from an excited state to a lower energy state. Outlines of the continents and a latitude-longitude grid have been added for reference.
The right side of the image shows the Sun-facing side of Earth, revealing daytime airglow, but emissions at the North and South Poles extend to the left, into the night side. These are the aurora borealis (northern lights) and australis (southern lights). The northern lights are more clearly visible in this image because their location depends on Earth’s magnetic dipole field, which is tilted southward over North America at the top left of the image. At the southern horizon, the magnetic field is tilted slightly away from the Americas.
The speck of light visible over the western horizon is an ultraviolet star, 66 Ophiuchi (HD 164284).
GOLD launched from Kourou, French Guiana, on Jan. 25, 2018, onboard the SES-14 satellite and reached geostationary orbit in June 2018. Built by the University of Colorado Boulder’s Laboratory for Atmospheric and Space Physics, and managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland, GOLD will improve our understanding of the Sun’s impact on Earth’s upper atmosphere as well as the effects from terrestrial weather below. GOLD commissioning — the period during which the instrument’s performance is assessed — began on Sept. 4 and will run through early October, as the team continues to prepare the instrument for its planned two-year science mission.