By Christopher Phillips
We begin the month of October with the moon passing through its first quarter phase, providing us with a picturesque accompaniment to our evening stargazing activities. Spotting faint objects in the heavens, such as meteors and satellites, will remain possible until the second week of the month, when the moon passes through its full phase.
If you happen to have a pair of binoculars handy, then take the opportunity to observe the moon during the first and last quarter phases. As our closest celestial neighbor, the moon makes for a fascinating and enticing observational target, providing us with a real glimpse of a different world. The interplay between light and shadow on the lunar surface makes for dramatic views of ancient craters, mountain ranges and lunar seas known as maria (Latin for “seas”), all of which give us tantalizing clues as to the nature and geological history of our celestial companion.
Rather than containing liquid water like the seas of Earth, the lunar ‘seas’ are in fact vast plains of basalt, the remnants of ancient volcanic activity. It was in one such sea, Mare Tranquillitatis (The Sea of Tranquility), that humankind stepped foot on another world for the first time, when the astronauts of Apollo 11 successfully landed on the lunar surface in 1969. If the face of the moon were a historical text, then every crater, mountain and human footprint would be the words in its celestial story; a story that began 4.5 billion years ago with the birth of the sun.
The October sky still presents us with our last opportunity to do some planet spotting before the year ends. Jupiter and Saturn can both be found low in the sky after sunset. Jupiter can be seen in the southwest, approximately 15 degrees above the horizon, with Saturn a mere stone’s throw away in the south, at approximately 19 degrees above the horizon. The low position of both planets will of course mean that you will have to have a view clear of trees or structures, in order to spot these two giants of the solar system. Both planets will be visible until around 11 p.m.
I wish you clear skies for the month of October, and happy stargazing.
— Christopher Phillips is based at the University of Washington where he works as a research scientist on the Zwicky Transient Facility (ZTF), a wide-field astronomical survey. He is a lifelong stargazer with a passion for astronomy education and outreach. He specializes in Polynesian star lore, which he studied in Hawaii under the tutelage of native Hawaiian cultural practitioners.