Recent volcanic activity on Earth may mean that the moon will appear a particularly rich shade of red during Sunday's lunar eclipse, astronomer Ken Tapping says.
The moon will move to the earth's shadow from 7:33 pm. PT, with the total eclipse lasting from 8:41 p.m. to 9:43 p.m.
"The way the moon appears during an eclipse depends largely on what is happening in the Earth's atmosphere at the time," said Tapping, who works at the federal radio observatory south of Penticton.
If the atmosphere is relatively free of pollutants, the moon will be a light copper color, Tapping said.
If the atmosphere is more obscure, as Tapping said today, it is because of recent volcanic eruptions around the world, there is a better chance that the moon appears to be a "dark red and blood color."
If the atmosphere was much more contaminated than usual, the moon would look gray, Tapping said.
This is the only lunar eclipse that will be visible from British Columbia this year. So far, the climate is cooperating, as Environment Canada is forecasting a clear sky on Sunday.
While a lunar eclipse presents mostly an opportunity for some interesting observations, scientists can use the occasion to get accurate readings about how quickly the moon cools when its surface darkens, Tapping said.
"There is a huge difference between the daytime temperature of the moon from about 100 ° C during the day and about -100 ° C at night," said Tapping.
Usually the temperature drops relatively slowly when night falls on the moon, but with an eclipse the darkness arrives much more quickly, he said.
"Radio observatories like ours can use a lunar eclipse to accurately measure the temperature drop on the moon," said Tapping.
"Basically, with a lunar eclipse, it's like someone abruptly turns out the moonlight."
In the 1960s, when plans were being made for the first lunar landing, scientists were not sure whether the surface of the moon would be solid enough to support the weight of landing craft or whether the spacecraft would sink dangerously into the powdered substance.
Low-orbit flights, as well as measurements from radio observatories, helped scientists determine that the moon's surface would support the spacecraft's weight, Tapping said.
This July marks the 50th anniversary of the first moon landing.