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| The Top 10 for 2010 |
By Alan Dyer
The year 2010 brings a number of fine astronomical sights. Winter features Mars high, bright and close to Earth. Spring brings Saturn at its best. Summer shows off with a triple-planet gathering in the evening twilight, while the annual Perseid meteor shower peaks on an ideal moonless night. In autumn, Jupiter shines near Uranus. As a bonus, we may see a couple of moderately bright comets, perhaps even a naked-eye comet in October. To wrap up the year, we have a well-timed total eclipse of the Moon.
In chronological order, here’s our list of the top 10 celestial sights of 2010.
Click on photos to enlarge. |
 Friday, January 29
MARS CLOSE TO EARTH
The New Year opens with a close approach to Earth of the red planet. Minimum distance between Earth and Mars is on January 27, at 99 million kilometres. Although Mars shines high and bright in the winter sky, this isn’t a particularly favourable approach. Two days later, on January 29, Mars is officially at opposition, directly opposite the Sun. By coincidence, the Moon is full that night, so it, too, lies opposite the Sun. That evening sees the full Moon near Mars, then at its brightest, with the two worlds flanking the Beehive star cluster. Binoculars will nicely frame the scene.
Courtesy TheSkyX™/Software Bisque
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 Saturday, March 20
MOON CLOSE TO PLEIADES
For the past couple of years, we’ve enjoyed seeing the Moon pass in front of the bright Pleiades star cluster a few times a year. That series of occultations is now over, thanks to the Moon’s orbital path shifting over an 18-year cycle. But this spring, we do get a fine night with the waxing crescent Moon shining very close to the Pleiades in the evening twilight, an event visible over all of North America. Once again, binoculars will provide the best view (inset).
Courtesy TheSkyX™/Software Bisque (both)
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 Sunday, March 21
SATURN AT OPPOSITION
When an outer planet reaches opposition, it is then as large and as bright as it will appear for the year, rising at sunset and at its highest in the sky at local midnight. This year, Saturn’s opposition date falls on the first full day of spring, March 21. Its rings are then tipped open by 3.2 degrees (left), similar to their appearance last spring. Through April and May, the rings appear to close up, reaching a minimum tilt of 1.7 degrees at the end of May, giving us another “thin ring” spring of Saturn viewing.
Courtesy TheSkyX™/Software Bisque
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 Thursday, April 15
MERCURY AND VENUS PAIR UP
Spring is always the best season for sighting Mercury in the evening sky. This year, Mercury reaches its greatest angle away from the Sun on April 8, when it lies just 3.5 degrees away from brilliant Venus, making it easy to locate the small planet. A week later, on April 15, Mercury and Venus are still no more than a binocular field apart, and the Moon joins the inner-planet pair, poised just above Mercury. The next night, the crescent Moon sits between Venus and the Pleiades. As a bonus (inset, far right), Mars shines higher up in the sky, near M44, the Beehive star cluster.
Courtesy TheSkyX™/Software Bisque (both)
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 Wednesday, July 14, to Friday, July 16
MOON PASSES A PLANET TRIO
By mid-June, three planets—Venus, Mars and Saturn—have begun to converge in the evening sky, forming a neatly spaced line of worlds across the western twilight. By mid-July, they are more tightly grouped in the west. Over the course of three nights, the crescent Moon passes each planet in turn. While none are particularly close conjunctions, any time we have three naked-eye planets gathered in the evening sky plus the crescent Moon, we have a scene sure to catch the eye.
Courtesy TheSkyX™/Software Bisque
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 Thursday, August 12
PERSEID METEORS PEAK
While no one can guarantee a show as good as 2009’s outstanding display, the 2010 edition of the annual Perseid meteor shower does have the advantage of dark skies. This year, the crescent Moon sets early, leaving the sky dark all night for enjoying the Milky Way and the sight of dozens of meteors an hour shooting across the sky. The traditional peak falls in the early evening for North American viewers, so the timing is perfect. This is also the prime weekend for summer star parties.
Courtesy TheSkyX™/Software Bisque
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 Thursday, August 12, and
Friday, August 13
MOON AND PLANETARY TRIANGLE
The sunset sky on Perseid night also contains our three evening planets—Venus, Mars and Saturn—now clustered in a tight triangle that can fit within a binocular field. The thin crescent Moon sits just below the planet trio. From Canadian latitudes, the grouping is partly lost in the evening twilight. The next night, the Friday of many summer star party weekends, sees the Moon a little higher and more obvious. Hilltop locations with a clear horizon to the west will be best for catching the sunset scene.
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 Wednesday, September 22
MOON MEETS JUPITER-URANUS PAIR
As it did in 2009, Jupiter once again plays tag with an outer planet. Last year, it was Neptune. This year, it is Uranus. Jupiter spends the last half of 2010 retrograding back and forth near Uranus in Pisces. The first encounter is on June 8, when the two worlds lie just 1/4 degree apart, low in the predawn sky. But on September 21, Jupiter and Uranus both reach opposition and are due south in the middle of the night and 3/4 degree apart. The next night, the full Moon joins the duo.
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 Saturday, October 30
TWIN SHADOWS ON JUPITER
Jupiter takes centre stage in late autumn as the lone evening planet visible to the naked eye. Through a telescope, its orbiting moons provide a constant source of eclipses and occultations as they move around Jupiter. October 30/31 is one of the best nights of the year for a Jovian moon dance, as Europa and Ganymede both cast their shadows onto the planet at once. This double shadow transit is a late-night event visible all across North America, beginning at 12:15 a.m., EDT (10:15 p.m., MDT).
Courtesy TheSkyX™/Software Bisque (all)
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 Monday, December 20
MOON TOTALLY ECLIPSED
This is the big event of the year: a total eclipse of the Moon visible from across the continent. Totality, when the full Moon lies completely within the Earth’s umbral shadow, lasts for 73 minutes and begins at 2:40 a.m., EST (12:40 a.m., MST), putting the main event well into the wee hours of December 21. However, the reddened Moon lies high in the south, glowing amid the rich star fields of the winter Milky Way. (The next total lunar eclipse we can see is a much less favourable one, visible at moonset from western Canada on the morning of December 10, 2011.)
Far right: Courtesy Simulation Curriculum Corp.; inset: Courtesy TheSkyX™/Software Bisque
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