SJAA Ephemeris February 2011 | SJAA Home | Contents | Previous | Next

The Shallow Sky

Searching for Spots

Akkana Peck


February evenings are still a good time to catch Jupiter in the early evening sky, and see how the SEB is darkening. The planet is moving north and has just crossed the celestial equator, so it’ll be fairly high in the sky even when it’s past the meridian.

Mars, Uranus and Neptune are all too close to the sun to be of much interest this month.

Just after nightfall around the last week of February, look for a faint band of light stretching upward along the ecliptic. That’s the Zodiacal Light, and you’ll get a good viewing opportunity through the first week in March.

Really, most of the planet activity is in the dawn sky. Mercury is only visible briefly at the very beginning of February, but Venus shines brilliantly all month, and Saturn is in the morning sky as well.

And after you’ve looked at the morning planets, leave that telescope out and put on a solar filter. How ‘bout that sun?

We’re supposedly nearing solar maximum – back in 2006 NASA published a prediction that this solar cycle was going to be an especially active one, peaking “in 2010 or 2011”.

And now ... where are the sunspots? Nowhere, that’s where! A few measly spots show up from time to time, but mostly the sun’s face is all too clean. And the new prediction is that the cycle won’t peak until May 2013 ... and even then, it’ll probably be the lowest cycle since 1928, with a predicted sunspot number of only 90 (vs. 132 at the last maximum, back in 2001).

Just goes to show, you can’t trust anything! Even something as seemingly reliable as the sun! That’s what you get when you stick your planet in an orbit around a variable star.

Of course, the unexpectedly low sunspot number is causing lots of people to jump in and blame things like the current cold winter on our underactive sun. Yes, fewer sunspots do mean a cooler sun. Although sunspots themselves are cooler areas on the sun’s surface, more sunspots mean higher solar output, for reasons that aren’t entirely clear – perhaps higher temperatures in the bright halo around each sunspot, or perhaps as a result of the intense magnetic activity associated with sunspots.

Whatever the reason, fewer sunspots means a cooler sun, so ... climate change! Something to counteract global warming! Woohoo, maybe we can go ahead and keep driving that SUV!

Well, er, not really. In fact, sunspots are probably a fairly minor factor in climate here on earth.

Take the Maunder Minimum. Starting around 1645, this long period of extremely low sunspot activity corresponded with the peak of the “Little Ice Age”, a period of cooler temperatures and increased glaciation in Europe. Of course, we don’t know much about what the sun was doing before the Maunder Minimum – only three sunspot cycles had elapsed since Galileo first trained a telescope on the sun in 1611– but those first three solar cycles observed by Galileo and his contemporaries showed quite a few more sunspots.

And yet ... the cooling of the Little Ice Age started long before the Maunder Minimum. An increase in oceanic ice began as early as 1250, 400 YEARS early, and the climate continued to get colder all the way through the late 1600s. That’s a lot of time to be blaming on a sunspot cycle or two.

So our climate is still warming, and you’re still justified in getting on the waiting list for a Nissan Leaf. But meanwhile, on days when it’s clear, pull out that solar filter (the safe kind that goes in front of the aperture) and see if you can find some sunspots. If there aren’t any ... well, it’s still a good excuse to be outside soaking up a little vitamin D on a cold winter day.


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