Astronomical Events of 1990: A Stargazer’s Almanac

By Fred Schaaf
Published on January 1, 1990
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In 1990 the moon will come as close to Earth as will get for the rest of this century, and we'll witness two full moons in the same month: December.
In 1990 the moon will come as close to Earth as will get for the rest of this century, and we'll witness two full moons in the same month: December.
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In 1990, our sun is expected to enter a period of unusually high activity—perhaps the highest in centuries—producing many sunspots and solar flares.
In 1990, our sun is expected to enter a period of unusually high activity—perhaps the highest in centuries—producing many sunspots and solar flares.
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Sunlight, reaching the moon from the upper left in this illustration, creates its phases: 1) new moon, 2) crescent, 3) first quarter, 4) gibbous, and 5) full. The moon then wanes through the sequence in reverse.  
Sunlight, reaching the moon from the upper left in this illustration, creates its phases: 1) new moon, 2) crescent, 3) first quarter, 4) gibbous, and 5) full. The moon then wanes through the sequence in reverse.  
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The red planet, Mars, will shine with uncommon brilliance in the night skies this summer and fall.
The red planet, Mars, will shine with uncommon brilliance in the night skies this summer and fall.
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The Hubble Space telescope may answer the riddle of Neptune's Great Dark Spot.
The Hubble Space telescope may answer the riddle of Neptune's Great Dark Spot.

Whether you’re an accomplished amateur astronomer or simply a casual observer, 1990’s night skies will offer some real treats. Among the astronomical events of the months to come are the best look at Mars we’ll get until 2001, and many striking conjunctions (close pairings) of the moon with major planets. Topping the list, though, is the likelihood that the sun will reach an unusually high peak of activity rivaling even 1957-58’s record maximum. One result will be brilliant displays of northern lights visible virtually everywhere in the United States.

Sun and Northern Lights

The sun reaches a period of “maximum” activity–sunspots, flares, etc.–every 11 years or so. However, this year’s anticipated maximum–expected around March–may present us with a higher level of activity than almost any other year in recent centuries.

That’s the logical conclusion, at least, to be drawn from 1989’s activity, which produced dozens of naked-eye sunspot groups and counts of over 260 sunspots at a time by expert observers. (Never view the sun directly unless you have the proper filters and the expertise to use them.) Last year, solar flares disturbed radio and electrical systems all over the world (6 million people in Quebec temporarily lost their electricity thanks to one of the March flares). And on the nights of March 12 and 13, 1989, the northern lights shone spectacularly, casting glowing, fluctuating patches of red light across all the U.S. and as far south as Central America! [Editor’s note: For a thorough discussion of the northern lights, details on when and where to look for auroral displays, and tips on observing and photographing the phenomenon, see “Northern Lights Over America.”]

Moon

On December 2 this year, the moon will be as close to us as it will get in the final quarter of the 20th century. On that day the distance from the moon’s center to Earth’s will be just 221,545 miles–only 93 miles more than its absolute closest approach during the period 1750 to 2125. Also in December, the moon will be full twice in the same month–a situation not to be repeated until August 1993.

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