KFOG Broadcast - September 24, 2015

Stopped in at the KFOG studios to talk with Mike, Greg and Renee about the upcoming eclipse and the supermoon. Click here to listen.

Total Lunar Eclipse of September 27, 2015 - in San Francisco!

Sunday September 27 we experience a total lunar eclipse visible from North America and of course here in San Francisco. This eclipse features the Moon passing nearly through the center of Earth's shadow, meaning that the Moon will remain in eclipse for over an hour and should be fairly dark, at least on one side. And from San Francisco we will see the unique situation of a Moonrise that is of a nearly fully eclipsed Moon, an unusual sight.

Total Lunar Eclipse - geometry

The eclipse takes several hours to occur, from first touch of the Earth's penumbral shadow to last contact, but the main part of the eclipse is the most exciting part, that of 'Totality' when the Moon's surface is fully darkened by the shadow of the Earth. From the west coast, totality starts at 7:13 pm and ends at 8:22 pm. Given that the Sun sets at 7:01 pm, the local conditions should lead to a very interesting Moonrise (just moments after the sunset) with nearly all of the Moon eclipsed.

The San Francisco Amateur Astronomers (SFAA) will be set up at Pier 15 along San Francisco's Embarcadero (just next to the Exploratorium) for public viewing, as the rising Moon should make a lovely picture just above Treasure Island and the San Francisco Bay. We will be there from 6:30 until 8:30 pm.

Here are several excellent resources on the eclipse:

EarthSky: http://earthsky.org/?p=51212

Wikipedia: https://en.wikipedia.org/wiki/September_2015_lunar_eclipse

NASA: http://eclipse.gsfc.nasa.gov/lunar.html 

This Week Facing East

This Week Facing East

The dawn sky is punctuated this week with a spectacular lineup of some of the brightest celestial objects in the heavens. The waning crescent Moon is the centerpiece of the eastern horizon in the hour before sunrise, shimmering next to Venus, currently a blazing gem of a ‘morning star’ due east, piercing the darkness of the horizon well before the first light of day, and remaining brilliant until the glow of sunrise washes out the planet.

Fall is a great time for seeing the morning sky since the days are getting shorter and the darkness lingers longer each morning, giving early risers like me a chance to get in some astronomy before starting my day in earnest. Each morning this week as I step out of my front door facing east, I await the spectacle of some of the brightest stars in the entire night sky and the wandering visitor Moon this week, taking the stage with Venus to amaze me and all who take a moment to savor this sight.

Image courtesy Sky & Telescope. 

Change of the Season

Late Summer is a time when the heat waves set in, giving everyone a last taste of the warmth that longer days and warming landscapes bring. However, as Earth approaches the Autumnal Equinox, the days are becoming noticeably shorter as sunrises arrive later in the morning while sunsets arrive earlier in the evening. The dual effect is most pronounced around the time of the Equinox, as the amount of time the Sun spends above the horizon shrinks most rapidly in this period.

Change of the Season

Every day throughout the year, the time of sunrise or sunset changes slightly, extending the number of hours of sunlight from December until June, and reversing course from July until December again. However, the mid-points of this gradual change are the Equinoxes, the point at which the change is at its greatest (tip for the mathematically inclined: it is the maximum point of the first derivative of the duration of the day, a sine wave that is passing through an intercept J).

What does this feel like? Take note of this for the coming weeks as you experience your daily routine, and notice the time when brightness arrives in you morning and when darkness sets in each evening. The change is quite pronounced, with the amount of daylight diminishing by up to 30 minutes in a single week in mid-September, at mid-northern latitudes as we have in San Francisco. If you are located further north in latitude (Canada, Northern Europe) the effect is even more pronounced, with up to an hour in a single week! I find this fascinating and marvel every year at the dramatic changes that we all take for granted in our environment. Fall is indeed a season of great change. Savor the moments.