MONTREAL -- If they can stay awake, Canadians from coast to coast will get a chance to view a total lunar eclipse this week -- the first of four that will occur nearly every six months.

Total lunar eclipses occur twice a year but are not visible everywhere on Earth at the same time.

The year's first eclipse will begin just before 2 a.m. EDT on Tuesday and will offer ideal viewing for observers throughout the Western Hemisphere.

Andrew Fazekas, a spokesman for the Royal Astronomical Society of Canada, says North America hasn't seen a total lunar eclipse since 2011.

"We've actually had this cosmic dry spell that we've been under that's lasted over two and a half years now," he said in a recent interview.

Fazekas noted that North America has been out of luck while Asia and Africa have had their share of such eclipses.

"So we finally break that spell with this really beautiful total lunar eclipse where the full moon will turn an orangey-red in colour in the overnight period Monday night into Tuesday, April 14th to the 15th."

A total lunar eclipse occurs when the sun, the Earth and the moon are in perfect alignment so that the Earth's shadow completely covers the surface of the moon.

"You can see this one -- even within city limits -- just using your eyes," Fazekas explained.

"You don't need binoculars and it's totally safe to see a lunar eclipse. It's not like a solar eclipse -- you can watch it with your naked eyes."

A solar eclipse happens when the moon comes between Earth and the sun and blocks the sun.

Watching it directly without special precautions can be harmful.

For people on eastern time, this week's eclipse will occur mostly during the early hours Tuesday.

"You can expect it to start at about 1:58 a.m. eastern time," Fazekas noted.

"The full moon will rise in the local eastern horizon and it'll be quite high in the sky by the time the eclipse happens -- and that will really be kicking in at around 3:26 a.m. eastern."

The entire event, from the start until the moon is out of the Earth's shadow, will last approximately three and a half hours.

Fazekas also said the actual colour of the eclipse is hard to predict because that's influenced by the levels of pollutants and dust that are floating around the Earth's atmosphere.

"The more dust there is, the deeper orange and red will be the colour of the lunar eclipse," he added. "It varies from one event to the other and we'll just have to go outside and see for ourselves exactly what colour this lunar eclipse will be.

Fazekas, who calls himself "The Night Sky Guy," pointed out that, including Tuesday's eclipse, Canadians will get to see four in a row -- a series known as a tetrad -- over the next 18 months.

"That won't happen -- that tetrad of lunar eclipses-- for another 20 years," he said.

"So if you get clouded out or you just can't get up so late in the overnight period, then you'll have more chances over the next 18 months to see another total lunar eclipse."

The other three will occur Oct. 8 this year and April 4 and Sept. 28, 2015.