TORONTO -- If the sky is clear Tuesday morning, then most Canadians will get a chance to see a unique astronomical phenomenon.

The moon will pass by Mars, in what skygazers call the occultation of Mars.

"You'll have Mars and the Moon moving closer and closer together as the sun comes up. Eventually, the Moon will cover Mars, or occult it, and we'll be able to watch that happen from Canada 鈥� weather allowing, of course," Elaina Hyde, a professor of physics and astronomy at York University in Toronto, said Sunday on 麻豆影视 Channel.

What anyone looking up at that moment will see is the bright shine of Mars suddenly vanishing behind the moon.

B.C. and most of Alberta won鈥檛 get to witness the occultation. Should the skies be clear, Medicine Hat, Alta. will be the first sizable Canadian community to spot Mars vanishing behind the moon, at approximately 4:47 a.m. MST.

Over a period of 90 minutes or so, Mars will disappear west-to-east across Canada. call for the disappearance to occur in Winnipeg at 6:02 a.m. CST, in Toronto at 7:26 a.m. EST, in Montreal at 7:39 a.m. EST, in Halifax at 9:02 a.m. AST and in St. John's, N.L. at 9:51 a.m. NST.

In all areas, Mars will be visible in the sky for about three hours prior to its disappearance and will reappear on the other side of the moon approximately 75 to 80 minutes after it vanishes 鈥� although the reappearance will be difficult to spot if sunrise has occurred.

Calgary is too far west to see the vanishing act, but will witness the red planet's reappearance at approximately 5:59 a.m. MST. Ditto for Edmonton three minutes later.

The occultation will also be visible across most of the continental U.S., save for some parts of the West Coast, as well as Mexico and most of Central America.

"We're not going to have another chance to see an occultation of Mars by the moon this whole entire year," Hyde said. There will be four other occultations in 2020, all visible from the Southern Hemisphere.

The occultation will be too distant to be visible with the naked eye, but anyone with a telescope or binoculars will be able to spot Mars in its final moments before it vanishes and first moments after it reappears.

For everyone else, York University will have a telescope in its observatory pointed at the moon Tuesday morning, and will be as long as the view is clear.