BLOOMBERGÂ – At 6:47 p.m. in New York, the sun will cross the celestial equator and spring will begin in the Northern Hemisphere. The big moment will occur at 10:47 p.m. in London, 7:47 a.m. Saturday in Tokyo.
In Wellington, New Zealand, and Sydney, as well as Sao Paulo and the rest of the Southern Hemisphere, autumn will descend at the same time.
Aside from its annual trip north across the equator, the sun has been busy this week. It may not be quite right to anthropomorphize the nearest star, but this week it seems to fit.
As the U.S. was waking up Friday, a supermoon — so called because itâ€™s at its closest point to the Earth, and therefore looks larger than usual — was drifting in front of the sun.
â€œThe path of the Moonâ€™s shadow is quite narrow, so you usually have to travel to see a solar eclipse,â€ said William Pesnell, project scientist with the Solar Dynamics Observatory at NASA. Fridayâ€™s â€œtotal solar eclipse is visible only from the Faroe Islands and Svalbard, but most of Europe will see a partial solar eclipse.â€
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Earlier this week, the sun fired off a couple of eruptions that merged just as they arrived in the Earthâ€™s neighborhood, setting off a brilliant aurora display across the high latitudes.
All of which begs the question: With the supermoon between the Earth and sun, could our largest natural satellite be a shield in the event of a huge coronal mass ejection?
â€œNope, too small to make a difference,â€ Robert Rutledge of the U.S. Space Weather Prediction Center said in an e-mail interview.
The sun is pretty big.
The earth, by comparison, is about the size of an average sunspot, according to the National Weather Service.
The power of the sun is about to have a major impact on the Northern Hemisphereâ€™s weather.
As the sun creeps north and bathes the Arctic region in light and warmth, the weather mechanics across the entire hemisphere change, said Stephen Baxter, a meteorologist at the U.S. Climate Prediction Center in College Park, Maryland.
The temperature gradient from the North Pole to the equator weakens and becomes less extreme than it is in winter, when the cold, dark pole stands in stark contrast to the warm, bright equator.
â€œWe tend to see less large-scale storm activity,â€ Baxter said. â€œBig, large-scale storms develop in response to the very strong temperature gradients.â€
In the winter, a kind of conveyor belt sets up to move warm air north and cold air south in an attempt to bring stability to the atmosphere, Baxter said. This usually means bigger storms as the air masses collide.
In the summer, as the sun reaches its highest point in the sky, which is brought on by the tilt of the earth, the atmosphere settles down a bit. Except for hurricanes. The sun heats the oceans, which are the driving force behind hurricanes, typhoons and cyclones, Pesnell said.
And before we reach beachfront nirvana, the hemisphere, mainly the central U.S., will have to pass through a period ripe for tornado production, Baxter said.
Thereâ€™s a downside to everything.
So at 6:47 p.m. Eastern Daylight Time in the U.S., take a moment to consider the sun and how it is going to break the grip of winter and bring about spring.
Of course, in New York, Boston, Philadelphia and Washington, you wonâ€™t actually get to see the sun at that particular moment because … well … it will probably be snowing.
Snow spreading across the mid-Atlantic will reach New York by midday, dropping 3 to 5 inches before it mixes with rain and ends Friday night, said Michael Silva, a weather service meteorologist in Upton, New York.