I was in San Francisco this morning recording another podcast for the KFOG Morning Show Podcast Series. Morning Show Producer Irish Greg and I had a very spirited and lively conversation about planets, the Solar System, Star Parties, Iridium Flares, Dark Energy and Dark Matter. In a fast-paced 9-minute conversation we discuss everything from the phase of the Moon to the origin of the Universe. Get inspired to see the sky tonight: Click here to listen.
This week the sky features four of the brightest planets in a beautiful lineup in the sunset sky. The illustration on the left, borrowed from Sky & Telescope Magazine, demonstrates how the planets all align themselves in a path across the sky known as the Ecliptic. This line in the sky, actually a gentle curve from west to east across the south part of the sky, is the plane of the Solar System as viewed from our observing platform on Earth. We see fast-moving Mercury close to the Sun, then Venus, Mars and Saturn, a most impressive line-up.
To set this into perspective, the young Moon emerges from the glare of the Sun on Tuesday 13th, moving somewhat parallel to the Ecliptic but each day a bit farther south of the Ecliptic. This is because the orbit of the Moon around the Earth is slightly inclined to the rest of the bodies in the Solar System. And as we just had a Total Solar Eclipse on Sunday, the Moon is following a path away from the Ecliptic into what is called the "descending node" south of the Ecliptic.
One of the most dramatic spectacles of nature takes place Sunday July 11th, as the New Moon passes in front of the Sun and creates a Total Solar Eclipse over the South Pacific Ocean. This eclipse will be especially unique for those who travel to Easter Island to see it. As the shadow of the Moon sweeps across the ocean at speeds of up to 1000 miles per hour, the darkness will pass directly across Easter Island and the famous Moai, the large stone statues that are nearly 1000 years old.
I have experienced Total Solar Eclipses in the past and they are remarkable, not only for the brilliant image you see in the sky, but also for the dramatic changes in the environment you experience as the sky slowly darkens, the horizon changes color, the animals begin to react strangely, and the fellow eclipse-chasers react with great anticipation. Although I will not travel to this one, I plan to travel to one of the upcoming eclipses in the next few years.
The evening sky over the next few weeks offers a study in the changes that take place in the sky along the path of the Moon and the path of the planets. This is exciting to watch and helps to unveil some of the intricacies of the Solar System, something you can see right from your own backyard. For quite a while now I have been particularly fond of sharing the path of the planets across the sky (the "Ecliptic") while conducting star parties and giving astronomy talks. I find that the ability to visualize this band across the sky is an important one for those who wish to have a basic understanding of the motion of the planets across the sky. And for several months the bright planets, a collection of bright stars, and the monthly sweep of the Moon across the sky have provided a perfect laboratory for learning. This month is no exception.
Shortly after sunset there is an excellent parade of planets and stars easily visible as the glare of dusk fades, starting with brilliant Venus in the west, and then in succession from west to south are Regulus, Mars, Saturn and Spica. These bright objects show the line of the Ecliptic.
At the end of this week there is a total solar eclipse (unfortunately not visible
from the San Francisco Bay Area). The eclipse comes at the middle of an Eclipse Season and as such, the Moon follows a descending path below the Ecliptic in the days that follow the eclipse, in particular from the 12th to the 17th of July. As it moves from day to day, it swoops just below the Ecliptic and makes a pleasant arc across the southern sky below Venus and Regulus, then Mars, then Saturn and then Spica.
And in addition, we are just coming into a period of time when fast-moving Venus has close encounters with the other planets and stars along the Ecliptic, starting with a close encounter of Regulus on the 9th of July. More drama to come in the next few weeks -- stay tuned!
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.