Wake Up To Spring Tomorrow And See The Space Station

Harry Nynas of Duluth heaved shovels fresh snow on top of the high banks that have accumulated over the season along his sidewalk yesterday. Photo: Bob King

After shoveling another 8 inches of snow after a winter of white, the banks along my walkway are now nearly at eye level. If there’s a lawn under there, I’m gonna need a team of archaeologists to find it. No matter, that won’t stop spring.

Tomorrow morning at 6:02 a.m. (Central time) the sun quietly slips over the line into the northern half of the sky. We call this the vernal equinox or start of spring. For me it will be a matter of faith in the cyclical movement of the sun. For you, the zephyrs of the new season may already be blowing through your hair.

The tip of Earth on its axis causes the seasons. On the first day of spring or vernal equinox, we face the sun from the side and days and nights are approximately of equal length in both northern and southern hemispheres. Credit: Tao-olunga

On the first day of spring, Earth’s axis is oriented neither toward nor away from the sun. If the southern hemisphere represents the planet’s feet and northern hemisphere its head, tomorrow we’ll be showing the sun our belly or profile if you like. In winter, the northern hemisphere is tipped away from the sun with short days and a low, chilly sun. In summer, we’re tipped toward the sun with long days, a high sun and more heat than most of us need. But during the vernal and autumnal equinoxes, neither hemisphere has the solar advantage (or disadvantage) and equality rules. Days are 12 hours long, nights are 12 hours long.

The rising sun tomorrow will bring with it the start of the spring season in the northern hemisphere. Credit: Rick Klawitter

The sun also also rises due east and sets due west. If you’ve ever been puzzled by which direction is which in your neighborhood, face the sunset sun around the time of the equinoxes and stick out both your arms at your sides. Your right arm points due north, the left due south. Pretty handy, eh?

On the first day of spring the sun crosses the celestial equator, an imaginary extension of Earth’s equator onto the sky, moving north. As the sun moves north, it climbs higher and higher in the sky – with increasing daylight hours – until it’s highest on the first day of summer. Illustration: Bob King

Spring and fall are the in-between times when temperatures moderate and the sun rests for a brief moment between extremes. For folks living on the equator, tomorrow the sun will rise in the east and pass directly overhead at noon before declining in the west. Equatorial skywatchers will stand in their own shadows at local noon.

Take an imaginary flight to Earth’s south pole and tomorrow means something quite different. There the sun will hover along the horizon 24 hours straight, neither rising nor setting. Starting March 21, it won’t breach the horizon for another 6 months. What marks the start of spring for northerners means the beginning of fall for Australians and a temporary end of sunshine for itinerant Antarcticans.

As you’d expect, the situation is just the opposite at the north pole, where 6 months of daylight begins with tomorrow’s sunrise.

The sun sets due west tomorrow on the first day of spring in the northern hemisphere. Photo: Bob King

Our planet’s tilted axis combined with its yearly orbit makes such strange things happen here on the ground. Just think how monotonous the weather and daylight-length would be if our axis were straight up and down with no tilt. Our skewed planet is like an artist looking at the world from varied and surprising perspectives.

Spring also coincides with a series of fine morning passes of the International Space Station (ISS) for at least the U.S. and Canada. Less than an hour before spring’s start, the station will pass over northern Minnesota tomorrow morning. To find times when it’s visible from your location, log on to Heavens Above (which also provides excellent maps of its path in the sky) or key in your zip code at Spaceweather Satellite Flybys page. The ISS first appears in the western sky and moves eastward, appearing like a very bright, moving star.

Space Station times for Duluth, Minn. region:

* Tues. March 20 starting at 5:14 a.m. “Magically” appears out of Earth’s shadow high in the southern sky and moves east. Brilliant pass!
* Weds. March 21 at 5:58 p.m. across the northern sky
* Thurs. March 22 at 5:09 a.m. Exits Earth’s shadow at 5:09 a.m. above the North Star and moves eastward
* Fri. March 23 at 5:52 a.m. across the northern sky
* Sat. March 24 at 5:03 a.m. Exits Earth’s shadow just below the North Star and moves east
* Sun. March 25 at 5:46 a.m. across the northern sky

6 Responses

  1. Wayne Hawk

    Aloha Astro Bob!

    You may or may not be consciously aware of this, but you seem to be anxious for much warmer weather, judging by some (perhaps) inadvertent words in your last few articles. I have to smile when I sense your urgency because I remember living in Minnesota and basically loving those cold, snowy winters…that is, until about the last half of March.

    It was like some sort of natural “switch” would click inside of me and suddenly, I couldn’t see the beauty I used to see in ANY more snowfall or sub-zero temperatures that came after this time of year. I too would be looking forward to those “April showers and May flowers”, as they say.

    One thing you can be sure of Bob, spring always comes. Before long, it will be summertime and on those Minnesota days where the temperature reaches into the 100’s, you’ll long for these days where the snow banks exceeded our height.

    It has always amazed me how anything can survive in a state where the temperature can dip to -36 degrees below zero Fahrenheit to 103 (or more) degrees above zero Fahrenheit. That’s a 140 degree difference! It is incredible, isn’t it?

    Believe it or not, there are times where I actually do miss those extreme days!

    Aloha For Now!

    1. astrobob

      I appreciate your words Wayne. I rather suddenly felt the same way as you. Yes, I love winter and extremes and the skiing’s been great, but last night I had had enough. I’m sure I’ll rally again however, since we still have nearly a month left of winter – then the mud begins!

  2. Edward M. Boll

    Finally, I saw Panstaars. 2.3 magnitude. Barely visible with the naked eye. With 20×60 binoculars, I could discern a faint tail pointing directly to the opposite of the Sun’s set position.

    1. astrobob

      Wonderful news Edward! I just got back myself from an ~1 hour PANSTARRS viewing session. Biting 30 mph winds but beautiful comet in binoculars and through the scope. The nucleus is a small, brilliant yellow “pea”. Using Alpha And I estimated PANSTARRS magnitude at ~2.8.

  3. Larry M. Gibson

    Just found your blog today and found it very useful and informational. I have casually photographed comets since 1986. On 3-19-13 I photographed PANSTARRS at about 8:50 PM from Anderson, IN. I noticed you published photos from others. How would I send you a photo, if you are interested? Thanks. Keep up the good work.

Comments are closed.