Life & Family | Astronomy

The Maunder Minimum spanned the period from 1645 to 1715. Two lesser minima are also noteworthy: The Dalton Minimum, which took place from 1790 to 1820, and the Sporer Minimum, which extended from 1450 to 1540. What are these mysterious minima? They are periods during which the Sun was exceptionally “quiet” and lacking in spots.

Most people have seen sunspots in photographs; many have observed them through telescopes. Sunspots are common and usually easy to observe. But not anymore! For several years now, the sun has been virtually spotless. In 2008, the Sun lacked spots on 266 days; one has to go back to 1913 to find a year with so many spot-free days. The Sun has also been atypically quiet in other respects, hitting a 55-year low in radio emissions and a 50-year low in solar wind intensity. Needless to say, the trend continued in 2009.

So unusual is the Sun’s current behavior that scientists have begun to hold conferences on the subject. Even the press has taken notice: On April 21, 2009, the headline “Sun at its quietest for 100 years” appeared on the Press Association’s newswire; “The Missing Sunspots: Is This the Big Chill?” was a headline in The Independent on April 27, 2009; even the Times had a story. A big question is whether we are entering another solar minimum. This is of more than academic importance as previous minima have been associated with significant climate change: Europe suffered a “Little Ice Age” beginning with the Maunder Minimum; it snowed regularly in London in the early 1800s, at the time of the Dalton Minimum; and New York rivers often froze over in the early 1900s, a period when solar activity was relatively low. The past several decades have seen unusually high solar activity, which may have contributed to global warming. Since the Sun has lost its spots, however, the warming trend is reversing and even ocean levels (reflecting polar ice melt) have flattened. Perhaps a Solar minimum will call a halt to global warming and give us some time to break our fossil fuel habit. Stay tuned.

This February is a good time to examine Mars and Saturn. Both planets will grace the night skies, with Mars rising in the early evening and Saturn an hour or so before midnight. Around midnight, Mars will appear as a bright reddish star high in the sky. Mercury will be a morning planet rising in the Eastern sky an hour or so before the Sun. Most of the other planets will be up during daylight hours, and thus not visible in the evening skies. There are no significant meteor showers in February. There are about 9½ hours of daylight in February with a gain of about 12 minutes each week.