Clockwork Skies 
The night sky is like a great machine. It wheels overhead with clockwork regularity, with the same constellations returning to view at the same time each year.
This precision is reflected in three constellations that spin into view in this month's evening skies. They reflect a fascination with the machines that scientists and explorers used to study remote regions of Earth and the glorious skies above.
The constellations are Sextans, Antlia, and Pyxis -- the sextant, the air pump, and the magnetic compass. Around 9 o'clock, Sextans is low in the east, with Antlia and Pyxis climbing into view in the south and southeast.
Sextans was invented by Johannes Hevelius, a 17th-century German astronomer who used the sextant to measure the positions of stars with unprecedented accuracy. And navigators were using it to help plot their position on the globe as they sailed into new waters.
French astronomer Nicolas Louis de la Caille created Antlia and Pyxis a few decades later.
La Caille didn't stop there, though. He named other constellations for the telescope, the microscope, and the pendulum clock. Although the clock might seem out of place, it was really one of the most important inventions in history. It helped astronomers time their observations of the sky, and navigators plot their precise longitude on Earth.
These faint constellations are important reminders of the clockwork motions of the heavens.
Script by Damond Benningfield, Copyright 2010