It’s still spring, but the June sun is just about tracing its highest arcs across the sky. For all of the northern hemisphere of Earth, we are nearing the summer solstice when the sun reaches its peak altitude and exerts its greatest influence.
Our sun is 865 million miles wide (109 times Earth’s diameter) and contains 99.85 percent of all matter in our solar system. Most of the rest belongs to Jupiter, so the sun in the center barely registers the gravitational tug of the other planets, moons, asteroids, comets and everything else in our solar system.
The rotational axis of any planet matters even less to the sun. To it, the seasons on Earth, defined by the north pole’s greatest tilt toward the sun (the summer solstice) or away from it (the winter solstice), are largely irrelevant. Overall, the relationship between Earth and the sun is pretty one-sided.
This spring, we were reminded of how central the sun is to our lives with the last great American total solar eclipse on April 8, and phenomenal displays of the northern lights on May 10-11 from the biggest geomagnetic storm in more than 20 years, triggered by coronal mass ejections from the sun.
The chance to see another total solar eclipse in our region is gone for this generation, but the same is not true for auroras. The huge sunspot (15 times the size of Earth) responsible for May’s historic auroras, has rotated to the sun’s far side and back, and is again facing our way. If it launches a coronal mass ejection toward Earth, we could have strong auroras tonight or tomorrow. This could also happen before you read this, or not at all.
The moon is new tomorrow, so skies will be dark making faint auroras easier to see. Circumstances are similar to those before the May auroras, but it is too early at the time of this writing to say much more. Check for updates on Spaceweather.com or anywhere space weather news is available.
The subtle effects of auroras are easy to miss, but the summer solstice, which comes just over two weeks from now, dominates our lives. We’re pretty much already at “high noon” for the year, and have mostly set jackets and sweaters aside … at least for the time being.
This seems slightly strange given that it’s only been about a month since my friends and I were able to comfortably take our first nighttime walks in the woods wearing just T-shirts, a milestone I look forward to each spring as such conditions seem to take their time arriving. But come they do, along with opportunities to head out into the daylight after dinner. So far, an added bonus of this year’s extended evenings has been the low numbers of mosquitoes and other biting insects.
If daylight is your thing, and why you are happy that June has finally arrived, allow me to remind you of an old saying: “What goes up, must come down.” In other words, get your fill of long days now, before the reversal starts.
For most of us, that happens way too soon — right after the solstice. The promise of summer comes packaged with the inexorable slide toward winter. It starts with the sun at its highest and strongest, but immediately transitions into a season of diminishing daylight.
The saving grace is that even though the days are shortening, the warmest part of the year lags behind the solstice, just as the warmest parts of days usually come during the afternoon when the sun has already crested and is descending.
A few notable events surround the summer solstice starting with our earliest sunrise (5:13 a.m.) on June 14 — just over a week from now. The solstice itself comes a week later as the sun reaches its northernmost point in our sky. That’s when it traces its longest path and we get our longest day.
The summer solstice, which marks the moment the sun halts its northward march and starts falling south, comes this year on Thursday, June 20 at 4:50 p.m.
If we choose not to quibble over the few seconds of difference between the several days surrounding the solstice, we can say that for all intents and purposes, they are equally long. In Springfield, the sun stays up 15 hours and 15 minutes from June 18 to June 21. The days immediately before and after those differ by only a few additional seconds.
The day after the solstice — our first full day of summer — the sun is past its peak and we’ve begun our half-year descent into winter. A week after that, we get our latest sunsets, which in Springfield are at 8:30 p.m..
In Springfield, the summer solstice delivers 6 hours, 9 minutes more daylight than the winter solstice in December. We also get our briefest nights: about 8 hours 45 minutes. Subtract morning and evening twilight, and the darkest portions of night lasts just 7-1/2 to only five hours — depending on which definition twilight we use.
This year, the full moon which falls on June 21 — the day after the solstice — further diminishes these nights.
The farther north one goes, the shorter the nights are. It changes quickly. In Derby, Vermont, near the Canadian border, a solstice night is 22 minutes shorter than in Springfield. Go far enough and the sun doesn’t set on the solstice at all. That’s called the Arctic Circle.
The sun’s average distance is about 93 million miles, but it is now about 94 million miles away — several million miles farther than in winter. From way out there it supports most life on Earth, yet — if one stays exposed for too long — it can be quite harmful.
Never mind the incomprehensible scale of the rest of the universe; our existence pales compared to just the Sun, our parent star, which itself is an insignificant corner of the cosmos. The simple fact that we denizens of Earth are next-to-nothing floating in an endless void, seems reason enough to want to make our one shot here count.
There will be no moon tonight, so even if no auroras are visible, don’t pass up the opportunity to do some stargazing. The clearer the air, and farther from city lights you get, the deeper into space you can see.
Find rise and set times for the sun and moon, and follow ever-changing celestial highlights in the Skywatch section of the Weather Almanac in The Republican and Sunday Republican.
Patrick Rowan has written Skywatch for The Republican since 1987 and has been a Weather Almanac contributor since the mid 1990s. A native of Long Island, Rowan graduated from Northampton High School, studied astronomy at the University of Massachusetts-Amherst in the 1970s and was a research assistant for the Five College Radio Astronomy Observatory. From 1981 to 1994, Rowan worked at the Springfield Science Museum’s Seymour Planetarium, most of that time as planetarium manager. Rowan lives in the Florence section of Northampton with his wife, Clara, and their cats, Eli and Milo.
