SLAS Regular Meeting
Friday, March 16, 2012
7:30pm
McDonnell Hall
Washington University

When Worlds Align – A Solar Eclipse, A Transit Of Venus

by

Mr. Mark Jones
Amateur Astronomer
St. Louis Astronomical Society 

The Moon orbits the Earth in almost the same plane as the Earth orbits the Sun. The “almost” means that Earth, Moon, and Sun usually do not line up exactly twice per month – the Moon is usually above or below the Earth-Sun line. Only twice a year is the alignment close enough that eclipses can occur. This year, one of those times occurs on May 20, when the Moon’s shadow falls on the Earth to create a solar eclipse. The darkest part of the shadow is narrow, and it will not reach St. Louis, so we will see a partial solar eclipse.

Most of the planets also orbit the Sun in almost the same plane as the Earth does. When the alignment is close to perfect, we can watch the disk of one of the inner planets,  Mercury or Venus, cross the face of the Sun. Such an event, called a transit rather than an eclipse, is quite rare. A transit of Venus will occur on June 6. The next one will not happen until December 11 – of 2117.

Observing solar eclipses and planetary transits safely requires special equipment and knowledge, since the Sun is being viewed directly. Instant and permanent eye damage results from even a quick look at the Sun through binoculars or a telescope, unless the proper equipment and safety precautions are employed. Mark Jones will explain precisely when the May 20 partial solar eclipse and the June 6 transit of Venus will occur, and how to view them safely.

Mark Jones, currently the Secretary of the St. Louis Astronomical Society, is a veteran amateur astronomer with decades of experience in observing both daytime and night skies.
Astro 101

Using the Night Sky Network

Jim Small
St. Louis Astronomical Society

A brief tutorial on using the Night Sky Network for members of local astronomy groups.  We will show how to log in to RSVP for events and edit local information for recieving notifications from the network.  We will also show how to download events to iCal and other calendar programs so you don't miss a single star party!