The Victoria atmosphere has finally acquired some Spring like qualities. This means that it is almost time to launch the 2019 Public Outreach Season. The official kick off takes place on Saturday April 27th with Astronomy Day. From 10AM to 4PM the Victoria Centre will be hosting the session at the Royal BC Museum. Numerous tables devoted to all things Astronomical will be located in the Clifford Carl Hall. Three lectures will be delivered in the adjacent Newcombe Conference Hall. David Lee, the captain of the Astronomy Day Team has recruited leaders to organize the various tables and things are coming together nicely. From 7:30PM to 11PM, our cousins, the Friends of the DAO, will be hosting the first Saturday Star Party of the season at the Dominion Astrophysical Observatory. RASC members will be in force with their telescopes to act as tour guides of the Universe. RASC will also have an information table in the Centre of the Universe. Star Parties at the DAO will be held every Saturday until September 7th.
Victoria Centre usually hosts another type of Star Party each year. The main focus of this event is an observing session directed toward the community of amateur astronomers rather than the general public. Selecting the date of a Star Party can be a challenge. It should meet the following criteria: fall near a New Moon, have a sufficient amount of darkness, avoid conflict with other nearby Star Parties and … oh yes … enjoy favourable weather conditions. This year the Mount Kobau Star Party, near Osoyoos will take place between July 31st and August 4th and the Island Star Party, held at Bright Angel Park in the Cowichan Valley, will occur on the Labour Day weekend. Many Victoria RASCals are loyal attendees of the Island Star Party so it is best to avoid that weekend. The New Moon and amount of darkness are easy to predict. It is, however, a bit trickier when it comes to the weather.
The saying goes that climate is what you expect and weather is what you get. While climate statistics can let you down it does reveal that the atmospheric dice are loaded. One rudimentary statistic which has proven useful in this area is the chance of 5 consecutive days without rain. The premise is that if there is no rain during a 5 day interval it suggests the presence of a ridge of high pressure that is diverting weather systems away from the area and suppressing afternoon shower activity. Using 50 years of quality controlled precipitation data from Victoria International Airport I calculated that the chance of 5 consecutive days without rain varied from 65% on Aug 1st to 47% on Sept 1st to 29% on Sept 28th. These values suggest that favourable weather conditions may be more than twice as likely on August 1st than during the New Moon interval near Sept. 28th. During the last three summers, however, smoke from wildfires has frequently obscured the night skies during July and August. Also astronomical twilight ends at 8:43 PM on Sept. 28th compared to 11:13PM on Aug. 1st. As a consequence the Council is leaning towards holding the Victoria Centre Star Party from Friday Sept. 27th to Sunday Sept. 29th. The location will once again be the yard of St. Stephen’s Anglican Church in Central Saanich … which was rained out on Sept. 7th last year. Be wary of those climate statistics!