Scorpius now in view

The summer constellation Scorpius is now center-stage in the southern sky. It's always a treat to see the distinctive shape of Scorpius with red supergiant star Antares glowing in the sky. Through binoculars Scorpius is great because of an abundance of deep-sky objects in and near the constellation. And this week there is an extra treat as the moon passes through.

Star Party on Saturday 27 June

This Saturday is a chance to hear a great lecture and enjoy star gazing with the San Francisco Amateur Astronomers (SFAA) for their monthly star party on Mt. Tam. This month, Professor Lynn R. Cominsky of Sonoma State University is giving a lecture at 8:30 pm at the Mountain Theater. Her topic will include "blazing galaxies, intense stellar explosion and super-massive block holes" and should be quite captivating. Afterwards, the SFAA will set up telescopes for public viewing of the universe and there is a lot to see this time of year. The Moon will be a lovely crescent, Saturn is visible, and many deep space objects such as star clusters and nebulae will be on display. And if all goes well, I'll be there pointing out constellations with my trusty green laser pointer.

Hope to see you Saturday night - above the fog.

Eerie Moon

We all know what the Moon looks like when it is in its early phases, waxing from a thin crescent over a two-week interval of time through first quarter and then to full moon. Although many people might not be able to explain exactly which way the "horns" of a crescent moon are pointed, it's something that you just know is right when you see it. For us living in the Northern Hemisphere, the horns of the young crescent moon point left and up when you see the moon in the western sky after sunset. That is, they point primarily south (left) and up (east) because the moon is being illuminated by the setting sun -- which is typically to the lower right (northwest) of the crescent moon. If you suddenly saw the horns of the crescent moon pointing the other direction, you might find it strangely discomforting. I certainly would!

Each month as the moon wanes from full moon to last quarter to a thin crescent in the morning, the orientation of the crescent reverses compared to the first 14 days of the lunar cycle. But because these phases are visible late in the night and in the early morning, there are generally fewer opportunities to see the moon in these phases. When I am up late at night or very early before sunrise and I see an old moon in the sky, the reversal of the orientation of the horns always throws me off. This week and weekend if you are up late at night or early in the morning you can take note of this as the waning moon passes Jupiter (see image) and continues eastward in its path, slimming to a thin crescent by June 18-20. Sky and Telescope Magazine called the waning gibbous late at night an "eerie moon" and I can appreciate why they would call it that. Whenever you see the moon, be it a slender evening crescent just starting its 29-day cycle, or a bold full moon lighting up the night, or a waning gibbous, think about the view and how it makes you feel. If you can start to gain a familiarity with the phases of the moon, you will find it does indeed evoke different feelings depending upon which phase it is in.

Above The Fog: Star Parties on Mt. Tam

It's been foggy in San Francisco. Really foggy. It seems like we have one clear night and six foggy nights per week lately and that is not what an Urban Astronomer likes. So it was with delight that I drove myself and my daughter to Mt. Tamalpais last Saturday for the monthly lecture and star party put on by the San Francisco Amateur Astronomers (SFAA). The Mt. Tam lecture series has been going on for many years and features a wide range of speakers from different areas of astronomy and cosmology.

Following each month's lecture, the SFAA hosts a star party featuring a collection of telescopes, some homemade by SFAA members, pointing out the wonders of the night sky. Despite the foggy conditions in San Francisco and Marin, Mt. Tam is almost always a great vantage point because you are literally "above the fog" and despite the proximity to the city lights of the Bay Area, the viewing conditions on Mt. Tam are quite good. Last Saturday was no exception and the view of the first quarter Moon, Saturn and the spring and summer constellations was great. My daughter and I used an iPhone application called "Star Walk" to help us to identify the fainter stars in Libra and Virgo, to get a full picture of the big summer constellation Ophiuchus, and to even identify part of Centaurus. Using the "Star Walk" application we were able to see that the view from Mt. Tam toward the south was good enough for us to see the upper half of Centaurus and even though we could not see our nearest stellar neighbor, the Alpha Centauri system, we felt like we were nearly there. In fact, it was very interesting to see on my iPhone that the Southern Cross was only a few degrees below the horizon at that moment and even though we can never see it from 37 and 38 degrees north latitude (the Bay Area), I felt like I was *almost* there. I guess I need a vacation at a more southerly latitude ...

Blue Neptune

A first for me: Early this morning before sunrise was the first of three conjunctions between Neptune and Jupiter. The rare "triple conjunction" started this morning with a close passage of Jupiter near Neptune in Capricorn. The separation was less than half a degree (less than a moon-width) and the difference visually between giant Jupiter and its four moons and blue Neptune was dramatic. Neptune looks essentially like a dim blue star through binoculars -- and is invisible to the unaided eye.

I had never taken the time to look for Neptune in the past. Because it is so dim and nearly impossible to resolve to anything but a pinpoint of light, I had never been motivated to seek it in a field of dim stars. But with Jupiter as my guide, it was an easy find and a magical moment to see those two solar system objects in one field of view. The alignment of two very distant planets - one 450 million miles away, the other almost 3 billion miles away - in a compact cluster less than half a degree apart was nothing short of remarkable. Now that the two planets have lined up once, they will soon reverse course and move in retrograde motion across the sky and will have the second conjunction on July 13th. Then they will return to prograde motion and have their final conjunction on December 20th. This long slow process is rare indeed, but as Jupiter speeds eastward away from Neptune after December 20th, it will soon arrive near to Uranus and will have a triple conjunction with Uranus starting in June 2010. I'll be sure to catch that one as well - because - yes, because I haven't ever seen Uranus either!

Moon passing through Gemini and Leo

As we transition from spring to summer, during the early phases of the lunar cycle the Moon's path appears to jump out of the western twilight sky fairly steeply toward the zenith. Gemini is the zodiac constellation that appears highest in the sky compared to the 11 other constellations of the zodiac. Thus in springtime when the Moon passes through Gemini, it appears fairly high in the western sky. This week you can see the Moon on its journey first through Gemini, then briefly across Cancer, then into Leo and a flyby of Saturn.

I am fascinated by the daily lengthening of the minutes and hours of sunlight at this time of year. Each day the sun rises a minute earlier and sets a minute later. It's very interesting to watch the transition from sunset to dark moving later and later each evening. In addition to the timing of sunset, the location is also changing. The sun sets quite far north of west and the point of sunset continues to move north until the summer solstice.

Jupiter in the morning

Jupiter and the Moon are going to share the southern sky during the early morning hours the next few days. If you are up before dawn look south-east for the waning Moon and bright Jupiter. On the 17th the two will have a close encounter that should be a pretty sight for the naked eye or through binoculars.

KFOG Broadcast: May 13th, 2009