Astronomically, it will be a busy weekend with a “supermoon” on Saturday and the vernal equinox heralding the arrival of spring on Sunday.
Due to the sun’s gravitational pull, the moon comes closest to Earth every 18 years. This event coincides with a full moon on Saturday that will be larger and brighter than usual.
“The immediate name is a supermoon, and it’s a few percent larger than the normal full moon,” said George Loyer, president of the Robert Ferguson Observatory, Valley of the Moon Observatory Association. “It’s interesting to know about, but you’d have to measure it. It won’t look noticeably larger.”
Meteorologists predict that while the weather may improve, the full moon this weekend will likely not be visible through the storm clouds.
Technically speaking, the moon is at a distance of about 356,417 kilometers at its perigee, while at its apogee it is at its furthest distance from the earth, namely 406,917 kilometers.
However, not all perigrees and apogees are the same. While the moon is in its orbit, it is still subject to the gravitational pull of the sun, which changes the orbit slightly in cycles of about 18.5 years, Loyer said.
“Someone watching the sky might notice the difference,” said Ed Megill, director of the Santa Rosa Junior College Planetarium. “But it won’t be something that jumps out at you, so to speak.”
The moon, which is a quarter the size of the Earth, also exerts its strongest influence on the ocean during this time, causing some of the highest tides.
Bodega Bay will see a high tide of 6.2 feet at 12:29 a.m. Monday, a high tide of 6.3 feet at 1:08 a.m. Tuesday, and a high tide of 6.2 feet at 1:52 a.m. Wednesday.
The spring equinox, when there is an equal amount of daylight and darkness during the day, occurs on Sunday at 4:21 p.m. when the sun crosses the equator and enters the Northern Hemisphere.
“The sun is shining longer, it’s higher, and it’s the beginning of our warmer weather,” Megill said. “It’s called the beginning of spring.”
