The steerable 60 foot diameter dish antenna of the
One-Mile Telescope at
Mullard Radio Astronomy Observatory,
Cambridge, UK, is
pointing skyward
in this evocative night-skyscape.
To capture the dramatic scene, consecutive 30 second exposures
were recorded over a period of 90 minutes.
Combined, the exposures reveal a background of gracefully arcing
star trails that
reflect planet Earth's daily
rotation on
its axis.
The
North Celestial Pole,
the extension of
Earth's axis of rotation into space, points near Polaris,
the
North Star.
That's the bright star that creates the short trail
near the center of the
concentric arcs.
But the
historic One-Mile Telescope
array also relied on planet Earth's rotation to operate.
Exploring the universe at
radio wavelengths,
it was the first radio telescope to use
Earth-rotation aperture synthesis.
That technique
uses the rotation of the Earth to change the relative orientation of
the telescope array and celestial radio sources
to create
radio maps of the sky
at a resolution better than that of the human eye.