The Autumn evening sky is being dominated by one bright, shiny object: the planet Jupiter, which will be a highlight for several months in our skies. On October 28th, Jupiter reaches "opposition" in which it is in a line with the Earth and Sun (and no, that is not what has been causing the recent earthquakes in the San Francisco Bay Area!).
Image Courtesy NASA
When Earth travels around in its orbit, approximately every 13 months we have a close encounter with Jupiter. When we do, the gas giant looks impressive with or without a telescope. Without a telescope, Jupiter is extremely bright, easily 50 times brighter than the brightest stars in the sky right now. It rises due East just after sunset, and remains visible the entire night. Through a small amateur telescope, Jupiter is a fine target, easy to locate and impressive with bands across its disk and the four Galilean moons shining brightly. Now is the time to get out a telescope or binoculars and share the brilliance of Jupiter with someone.
When observing the night sky, I enjoy the slow changes of the seasons and the stars as they arrive into the evening sky. The Moon and planets change their positions regularly, sometimes quite quickly. And transient events such as meteor showers and eclipses bring some drama to the sky. But the backdrop of stars is supposed to be constant and unchanging. And that brings me to the motivator for this blog post, the variable star Mira.
Mira is a well known variable star, and lately it has been changing its brightness very fast and over an extreme range, so that this star that is normally invisible to the naked eye is suddenly visible in the evening sky. I stepped outside this evening and found it near Jupiter, just a "thumb and a little finger away" as described by astronomy writer Tony Flanders in this Sky & Telescope article. I'm pleased to have found this special star that is now 1000s of times brighter than usual. If you feel up for a challenge, try to find it tonight.
The Orionid Meteor Shower peaks for the next two mornings, October 21 and 22, as the Earth passes through a debris stream left by Halley's Comet. Like all annual meteor showers, the Orionids occur at the same time each year because the Earth, in its 365-day trip around the Sun, passes through areas of increased debris, leading to a much more focused period of time with meteors flying into Earth's atmosphere and creating those beautiful streaks of light that magically light the sky for a moment and then vanish without a trace.
The name Orionids tells us that the meteors in this shower appear to emanate from the constellation Orion, the beautiful winter sky constellation. But like the best meteors in any shower, you won't see Orion until after midnight as it rises out of the east. Meteor showers are best observed between midnight and sunrise, when you are viewing meteors entering our atmosphere on the 'front face' of the Earth. Given that sunrise is quite late this time of year, take advantage of that and get up just ahead of dawn's light, around 6:15 in the San Francisco Bay Area.
The Full Moon dominates the night sky this week, lighting the Autumn landscape and making its presence known as the soft grey glow of moonlight washes out all but the brightest stars in the sky. But even as the stars take a back seat in the night sky, the giant planet Jupiter shines steadily next to the Moon, undiminished by the intense glow of our nearest celestial neighbor.
Jupiter is nearing "opposition" in which it is at its closest approach to Earth for 2011. That means that it is also at its brightest, outshining all other celestial bodies in the night sky right now, except the Moon. For the next few nights as the Hunter's Moon passes near Jupiter, your attention will be drawn to the dazzling brightness of the largest planet in the Solar System. And once the Moon has moved into Last Quarter phase next week, Jupiter will remain steadfast in the evening sky, waiting for you to find it in binoculars or a small telescope. Take a moment and look up close if you have not seen Jupiter up-close. It's a worthy (and easy) target.
There are many ways to get involved with astronomy. No matter where you live, you can find local clubs and events using the Night Sky Network website. Just about anywhere you go, you'll find a friendly astronomy club ready to welcome a new guest or member.
I take part in a few specific events. One of my favorite places to show off the night sky is at the weekly NightLife event at the Cal Academy in Golden Gate Park, every Thursday night. When the skies are clear, I can be found on the Living Roof showing off the skies with a trusty laser pointer, alongside Academy staff with telescopes pointing at the Moon, Jupiter, or other objects of interest. It is an excellent place to have fun and learn some new things about the night sky.
On November 5th, I'll be working with Tucker Hiatt of Wonderfest during the Bay Area Science Festival with a star party on Mt. Tamalpais in Marin County. We're calling the event "Nekkid-Eye Nightscape," and it will follow a lecture called The Milky Way as Dark Matter Laboratory. Tucker and I will give an introduction to the night sky, showcasing the best and the brightest objects in the Autumn Sky. After the lectures, the SFAA will be there with wonderful telescopes to show off the night sky up-close and personal.
In 2005 I began writing a column for the San Francisco Waldorf School newsletter called "The Urban Astronomer." I started this blog in 2007 as a place to archive my articles and to offer additional insights on the night sky - even if you live in a big city. In 2008 I became an occasional guest on the KFOG Morning Show, and more recently on KALW and KGO. Archived shows are posted on the blog.