COEUR d’ALENE — This Saturday will mark the second blue moon of 2018, a feat that will not happen again until 2037, Casey Hallett said.

Hallett has taught elementary astronomy at North Idaho College for six semesters. She said the blue moon’s show starts Friday evening and continues into early Saturday morning.

“I would suggest looking at the moon starting March 30th at its rise at 6:28 p.m. It then moves into official full moon at 5:36 a.m. the morning of the 31st before it sets at 6:57 a.m.”

She added that the moon won’t look much different on Saturday than it will look on Friday evening. “So if you’re not a Saturday early bird, you can still get a good view before bed on Friday night.”

A spotting scope or a cellphone camera is a good alternative for those who don’t have telescopes, Hallett said. “As long as the sky is clear, we shouldn’t have any problems seeing it from the city,” she said.

Hallett explained that the time it takes the moon to go from new moon phase back to new moon phase is 29.5 days, thus making it rare to see more than one full moon in a single month. A blue moon is the second full moon of a calendar month.

A blue moon took place earlier this year on Jan. 31, which coincided with a lunar eclipse and a supermoon. This weekend’s lunar event will be unique because it marks the first time since 1999 that two blue moons have taken place in one calendar year, Hallett said.

“These types of celestial events show us how dynamic our solar system is,” she said. “The phases of the moon are caused by the alignment of the sun, Earth, and moon. Because Earth is rotating around the sun while the moon is rotating around Earth, the lunar cycle is dynamic and is why the phases of the moon don’t always occur on the same days of the month and why a blue moon is a rare event.”

Hallett earned her B.S. in Physics and M.A. in Education from the University of La Verne in California, an M.S. in Physics from the University of Idaho, and wrote her thesis on mountain chains and hills on Saturn’s largest moon, Titan.