Mercury Transit

November 8, 2006

What is a transit? -|- What Makes this Transit Special -|- Viewing the Transit in the SF Bay Area

Technical Information -|- Viewing the Transit Yourself -|- For More Information

What is a Transit?

A transit occurs when a planet crosses the line of sight between the Earth and the Sun. From Earth, we see a small circular dot on the face of the Sun, caused by the planet's shadow.

From Earth, only transits of Mercury and Venus are possible, because they orbit closer to the Sun than does the Earth. The outer planets (Mars, Jupiter, Saturn, Uranus and Neptune) are all farther from the Sun than Earth, and so they can never get between us and the Sun.

There is another celestial body that can cross between the Earth and Sun and cast its shadow on Earth: our Moon. Because the Moon is so close, it appears very large in our skies and completely blocks the Sun. For this reason, we call this event an eclipse. But the principle behind eclipses and transits are the same.

What is a transit? -|- What Makes this Transit Special -|- Viewing the Transit in the SF Bay Area

Technical Information -|- Viewing the Transit Yourself -|- For More Information

What Makes this Transit Special?

This is the first time Mercury has transited the Sun since 2003. This is a relatively rare occurrence. There are approximately 13 transits of Mercury each century. The next transit of Mercury will not occur until May 9, 2016.

The transit features four distinct events, as Mercury's disc moves into and across the face of the Sun:

1. First Contact, at 11:12 am, occurs when Mercury's disc first touches the Sun's disc. Mercury's disc has not fully moved in front of the Sun yet.
2. Second Contact, at 11:14 am, occurs when Mercury's disc has moved fully in front of the Sun, but the edges of both discs are still touching.
3. Third Contact, at 4:07 pm, occurs when Mercury's disc starts to move off the Sun's disc.
4. Fourth Contact, at 4:09 pm, occurs when Mercury has fully moved off the Suns's disc, but the edges of both discs are still touching.

What is a transit? -|- What Makes this Transit Special -|- Viewing the Transit in the SF Bay Area

Technical Information -|- Viewing the Transit Yourself -|- For More Information

Viewing the Transit in the SF Bay Area

Here in the San Francisco Bay Area, you can view the transit at the following locations:

San Francisco - Randall Museum

The Randall Museum will host a special event sponsored by the Randall Museum, San Francisco Amateur Astronomers, and San Francisco Sidewalk Astronomers.

From 11am until 1pm, the event is open for children and schoolgroups only. Sessions in the Randall Museum auditorium, as well as special educational activities will introduce children to the Sun and planets. Solar telescopes available for children to view the transit as it happens. From 1 pm until the 4 pm, the event will be open to the general public to view the transit.

The Randall Museum will also display a live feed of the Exploratorium webcast for guests, which is open to everyone.

San Francisco - Exploratorium

The Exploratoriumwill sponsor a live webcast of the event, from the Kitt Peak National Optical Astronomy Observatories in Arizona. For more information, see the Exploratorium page on the transit.

Oakland - Chabot Space and Science Center

The Chabot Space and Science Center will offer free viewing of the transit with paid admission.

Pleasant Hill and Walnut Creek - Mount Diablo Astronomical Society

The Mount Diablo Astronomical Society has one public event and 3 private events scheduled for the Mercury Transit on Nov 8. The public event is from 11am to 5pm at Diablo Valley College on the grass by the Library, next to parking lot 3. For more info, contact outreachinfo@mdas.net or visit http://www.mdas.net.

San Mateo - San Mateo County Astronomical Society

The College of San Mateo together with the San Mateo County Astronomical Society (SMCAS) will be hosting an event from the new rooftop observatory at College of San Mateo. The public is invited to join students, faculty, staff, and members on Bldg. 36, 4th floor on the College of San Mateo campus. For directions and parking information visit: http://www.collegeofsanmateo.edu/astronomy/ or call: 650-574-6272.

Santa Clara - The Astronomy Connection

Michael Swartz of the Bay Area Astronomy Connection is planning on setting up his refractor telescopes and solar gear in the main courtyard by the main fountain at the Santa Clara civic center. It is right by the IT department office and also right next to the cafeteria. He will be there from around 10:30am until the transit completes.

San Jose - San Jose Astronomical Association

The San Jose Astronomical Association is sponsoring free public viewing of the transit at Houge Park in San Jose, near Campbell and Los Gatos.

Salinas - Fremont Peak Observatory Association

The Fremont Peak Observatory Association (FPOA) is offering public viewing of the transit on the campus of the Hartnell Community College in Salinas in front of the campus planetarium.

Auburn - Starry Starry Nights

A group of astronomers (Starry Starry Nights) will be setting up telescopes to show the transit from 11:30 AM about 4 PM for free public viewing.

Location is in Auburn, about 40 miles above Sacramento, (along highway 80) at a park known as the American River Canyon Overlook Park (also known as the Auburn Skate Park).

Directions: To get there, go to downtown Auburn, to the historic Courthouse. One of the roads branching from there is Auburn-Folsom Rd. Take that east to the third stoplight (about a mile). This is Pacific Avenue. Turn left. Go about 0.8 mile to the Auburn Dam Overlook, which is on your right. We set up at the far (east) end of the parking lot.

What is a transit? -|- What Makes this Transit Special -|- Viewing the Transit in the SF Bay Area

Technical Information -|- Viewing the Transit Yourself -|- For More Information

Technical information

Here is the local information for the SF Bay Area, courtesy Dr. John Westfall of the Association of Lunar and Planetary Observers: