Vernal Equinox Monday is Official Spring for Oregon Coast, Washington Coast: Science Curiosities

Published 03/19/23 at 5:23 AM
By Oregon Coast Beach Connection staff

(Astoria, Oregon) – Ya gotta love vernal equinox. It's the first day of official spring. It contains some engaging astronomical aspects in that this is the day when both the north poles and south poles of the Earth are at an equal distance from the sun – whereas any other day of the year one is always tilted closer. (Above: Long Beach, Washington - Oregon Coast Beach Connection)

Plus, on the Oregon coast and Washington coast, it means more and more sunlight, and often increasingly warmer days even at the end of March (though it's often known to get rainy during the two spring breaks). However, there are some real intricacies that come about for the region that may surprise you.

According to Jim Todd, astronomy expert at Portland's OMSI, March 20 is the big day of the official switch of seasons. The vernal equinox brings true equilibrium to the Earth: those poles are both 92.6 million miles from our family star. The whole thing really kicks in at 2:24 p.m. here in the Pacific Northwest, the exact instant the sun stands directly over the Earth's equator.

Above: Coos Bay area as seen from space, from the ISS

Todd said the term “vernal” comes from the word green, and “equinox” means “equal night.” Both are derivatives of Latin. Equinox also represents the idea that the hours of night and daylight are absolutely equal on this date. However, there's a caveat there – keep reading.

If you're on the Washington coast or Oregon coast, as well as Portland or Seattle, you'll get to witness the stellar fun.

“As seen from Portland on March 20 and 21, the noon sun will reach its mid-point in the sky near 45 degrees from the southern horizon,” Todd said. “On the day of an equinox, it is a good day for finding due east and due west from your own backyard. Just go outside around sunset or sunrise and notice the location of the sun on the horizon with respect to familiar landmarks.”

Oceanside at night, Oregon Coast Beach Connection

Todd said the Earth's axis is tilting at 23.4 degrees in summer, giving us the sun's rays more directly then and keeping things warm. When winter comes, we here in Oregon and Washington have titled away from the sun, which means the sun has to go through more layers of atmosphere, thus cooling its rays.

Therein lie some weird possibilities, if you think about what if there was no tilting action of the Earth.

“If the Earth rotated on an axis perpendicular to the plane of the Earth's orbit around the Sun, there would be no variation in day lengths or temperatures throughout the year, and we would not have seasons,” he said.

Now there's a kooky little hitch in all this. The more scientifically exact moment of equal day and night actually happened on March 17, at least for Portland. The exact times and dates of that 12-hour effect differ somewhat for the Washington coast and Oregon coast, because of their positions away from Portland or from the inland areas closest to them. Towns on those coastlines have about a 7-minute or less difference in sunset / sunrise times than the valley towns closest to them. And those differences change considerably the farther north you go into Washington or down towards the south Oregon coast.

The fact that Portland is near the 45th parallel factors in. March 17 as the date was when the region around the parallel had 12 hours of day and 12 hours of night. Sunrise was at 7:18 a.m. and sunset at 7:19 p.m.

On March 20, sunset in Seattle, Washington will be 7:22 p.m. Sunset in Moclips is 7:29 p.m.

For Portland, Oregon, exact sunset is 7:23 p.m. It's 7:28 in Seaside on the north Oregon coast.

For Bandon, it's 7:30 p.m., while in Medford sunset occurs at 7:24 p.m.

“At the 45th latitude North, the time it takes for the sun to fully rise and set, which is several minutes, is added to the day and subtracted from the night, and therefore the equinox day lasts a little longer than 12 hours,” Todd said. “Another reason why the day is longer than 12 hours on an equinox is that the Earth's atmosphere refracts sunlight.”

Now, those hours after dark will start shrinking faster and faster. This will continue through September 25, when the autumnal equinox begins. Even so, and this is very true even in winter, there's another fun fact for the Washington coast and Oregon coast: as you can see by these times, if you want just a few extra minutes of daylight, head to the beaches.

Another intense surprise: Sunset Science: Dusk Isn't What It Seems on Oregon, Washington Coast

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Andre' GW Hagestedt is editor, owner and primary photographer / videographer of Oregon Coast Beach Connection, an online publication that sees over 1 million pageviews per month. He is also author of several books about the coast.

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