MERCURY, the Solar System’s smallest planet, joins the planets visible to us this month when it pops into view in the pre-dawn eastern sky during the last two weeks of October. Mercury may be spotted as early as October 21st an hour before sunrise, but by October 28th and through the end of the month it will be brighter and higher in the sky so that it can be spotted more easily. Again, look an hour before sunrise and we will be able to see it with the unaided eye low in the eastern sky.
JUPITER and SATURN remain bright and prominent in our southern evening skies all month. Jupiter, the brighter of the two, trails Saturn and will not set until around 3 am. Saturn sets about an hour earlier. The waxing gibbous Moon will appear just below Saturn on October 14th; and just below Jupiter on the 15th.
VENUS brightens this month so it will be easy to see soon after sunset in the southwestern sky, though it will only be 8 to 12 degrees above the horizon. This is the distance covered by a clenched fist held at arms-length against the sky.
October’s FULL MOON on October 20th, the first Full Moon after the Autumnal Equinox (September 20th), is often referred to as the HARVEST MOON. Farmer of olden days, before lights on tractors and combines, often used the light of this Moon to continue to bring in their harvests for some time after twilight had faded.
Just how bright is the Full Moon? Many of us might guess 1000 times brighter. But Sunlight is actually 450,000 times brighter than the Full Moon! And though the Full Moon looks big to us compared to the dots of light that are stars, or the brighter light of planets, it would actually take 180 Full Moons stacked together against the sky to fill the space from the horizon to a spot directly over our heads (the zenith)!!!
And a final startling lunar fact is that the Moon is not very shiny. It looks dazzling white because our eyes and brains reset brightness levels according to our surroundings. The Full Moon hovers against a black background sky so our brains paint it white. In reality, the Moon only reflects about 11% of the sunlight it receives, which means it is actually a dim, dark, and rather desolate place!
Our universe is surely a strange, interesting, and surprising place!