There are many astronomy resources on the web that help you to better understand the night sky. One of the finest is the 5 minute video from Sky & Telescope Magazine entitled SkyWeek. Hosted by associate editor Tony Flanders, I find these weekly videos to be quite illuminating, combining the highlights of the night sky with science and understanding of the things you are seeing. Tony delivers all of this with a great sense of wonder and enthusiasm, without talking down to the audience. I always feel like I am being taught something new and interesting, combining simple observations with deeper astrophysics.
I had the pleasure of spending time with Tony and his family while on an eclipse expedition several years ago, and I really liked how he could balance the far ends of the spectrum of observational astronomy and astrophysics. He has been creating SkyWeek episodes for about one and a half years, and I hope he continues for a long time into the future. The show is carried on many PBS affiliates, adding considerable depth to the quality educational lineup available on public television.
Saturn reaches a special moment in the sky for us Earth-bound viewers, a time when conditions are most favorable for viewing the 2nd largest planet in the Solar System in all its glory. Opposition is the time when the planet is directly opposite the Sun, from our Earthly point of view. That means a few things: (a) it is at its closest to Earth, and therefore brightest for the year, (b) it is visible all night, rising just after sunset and setting just before sunrise, and (c) it is illuminated straight overhead from the Sun, much in the way we view a full moon.
For the city dweller, Saturn is an easy object to find, outshining most of the stars in the sky except nearby Arcturus, and its rival planet Jupiter (which is slowly fading into the west earlier each night). Saturn glows a yellow-white hue, in contrast to another nearby bright star, Spica. To find Saturn, it rises right after sunset this evening and for the foreseeable future, and glides from the south-east to the southern sky, and then across to the south-west after midnight.
If you have a telescope, now is the time to put it to work, as the view of Saturn will be at its finest. Wait a little while after sunset until Saturn is higher in the sky, less susceptible to atmospheric effects. The ring system is tilted 18 degrees toward Earth, so the view is quite good, and as anyone who has seen Saturn in a telescope will attest, the rings are amazing to see with your own eyes.
As the Moon reaches first quarter phase, I find myself drawn to the Moon's 'terminator', the line that separates dark from light. At first quarter phase (happening this week), the Moon presents Earth a very fine view of the terminator, exposing the highs and lows of the surface of the Moon. As I regularly point out to people during star parties, the region of the terminator during the waxing phase of the Moon is the region of sunrise, the place on the Moon where the Sun is just emerging above the horizon for what will eventually be a long lunar day (this takes 29 'Earth-days' to complete). As such, the illumination on the Moon's surface is much like you would expect on Earth at sunrise: long shadows across the land, with unusual features such as valleys and mountains being partially illuminated. The image attached (courtesy of APOD) shows the view through a telescope of the terminator, with shadows clearly visible in the craters and from the peaks of the mountains.
Tonight will be a fine time to peer at the Moon with anything you have at your disposal. It's the easiest target to find with a telescope or binoculars, and it's always visible even in the worst city lights. And it's a treat to see something unusual yet familiar, the sight of sunrise on another world.
It's spring, and that means it's time for star parties at the Mountain Theater on Mt. Tamalpais in Marin County. Always a favorite place for stargazing, I am looking forward to being a part of the magical Saturday nights with lectures, star gazing and amateur astronomer telescopes each month.
The Friends of Mt. Tam (formerly the Mt. Tam Interpretive Association) have been sponsoring astronomy nights on Mt. Tam for 25 years, and this year will be another excellent one with monthly lectures from professional astronomers on topics such as Dark Energy, Asteroids, Mars Exploration and Climate Change. Following each lecture, I give a short tour of the night sky, and the San Francisco Amateur Astronomers host a star party with powerful telescopes to peer into the dark sky visible high above the fog on Mt. Tam.
The nights on Mt. Tam are a terrific astronomy experience and the price is free, so there's no excuse for not taking part. Families are welcome, and guests bring food and drink as well as cushions and warm blankets to really enjoy the evening there. The first event kicks off this Saturday April 13th at 8:30 pm, featuring Dr. Robert A. Rhode of the Berkeley Earth Surface Temperature. His lecture is entitled “Understanding the Climate Change of the Last 250 Years”. Click here for details.
I hope to see you Above the Fog on Mt. Tam sometime this season.
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.