This observation was taken as part of the GaLactic and Extragalactic
All-sky Murchison Widefield Array (GLEAM) survey (Wayth et al. 2015), and
recently reprocessed with an improved pipeline aimed at releasing the
Galactic part of the survey to complement the existing extragalactic
catalogue (Hurley-Walker et. al 2017). Spanning 72 to 231 MHz, the survey
explores the sky at low frequencies, and visible in this image are
bubble-like supernova remnants, extended HII regions, background radio
galaxies, as well as the diffuse synchrotron emission of the Milky Way
itself. This image was constructed using just five minutes of observing,
50% of the field-of-view, and 60% of the bandwidth, which has been split
into three "radio colours": red = 72 - 103 MHz,
green = 103 - 134 MHz,
and blue = 139 - 170 MHz. By happy accident, our Moon is silhouetted
against the background glow of the Milky Way. The red dot in the centre
shows the reflection of the Earth's FM radio transmissions from the
tangent plane of the face of the Moon; the rest appears black because as a
blackbody, the Moon is much dimmer than the Milky Way's bright synchrotron
emission. McKinley et al. 2013 used the Moon's FM reflection to determine
how bright the Earth might appear at meter wavelengths to an observer
beyond our own solar system.