OCTOBER 7 After a week of looking for easy-to-find objects, it's time to scan the night sky for some more challenging targets. Here, we present the first of four Sky Surprises in Starry Night's Fall Sky Tour.
Most people have seen the five brightest naked-eye planets, yet there is a sixth planet that can be spied without optical aid and another which can be picked-up using just a good pair of binoculars.
Youll have to know exactly where to look for these planets, of course. Both are currently well placed for viewing in the evening sky, and with the bright Moon out of the way for much of this week, it will be a good time to look for them.
Barely visible to the unaided eye on very dark, clear nights, the planet Uranus, currently shining at magnitude 5.8, is now visible during the evening hours among the stars of Capricornus, the Sea Goat. On a scale used by astronomers to indicate the brightness, larger numbers mean dimmer objects. The dimmest visible to the unaided eye under very dark skies is about 6.0.
Given Uranus' near invisibility, it is best to study the accompanying sky map first, then scan the proper region of the sky with binoculars to find the planet.
| Your Tour Guide | | Maps and images made with the new version of Starry Night Pro software. Click to enlarge | | 
Positions of Neptune and Uranus at 8 p.m. local time from mid-northern latitudes.
| | The planet Uranus as seen in ... The planet Neptune as seen in ...
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Using a magnification of 150-power with a telescope of at least 3-inch aperture, you should be able to resolve the planet into a tiny, pale-green featureless disk.
Greater challenge: Find Neptune
Neptune is much too faint to be perceived with the unaided eye, lying at an average distance from the Sun of 2.8 billion miles (4.5 billion kilometers). It is slightly smaller than Uranus, with a diameter of 30,600 miles (49,250 kilometers).
Currently at magnitude 7.9, Neptune is more than six times dimmer than Uranus.
Nonetheless, if you have access to a dark, clear sky and carefully examine our map, you should be able to find Neptune it with a good pair of binoculars. Like Uranus, Neptune can be found among the stars of Capricornus.
You might try using the fifth-magnitude star Upsilon Capricorni to steer you toward Neptune. Right now, Neptune is only about a degree (about a full Moons width) to the east of this star.
Located very close to Neptune -- only 4 arc minutes (or less than 1/6th of a Moon diameter) -- is a star catalogued as HIP102217. At magnitude 7.3, its a bit brighter than Neptune, but Neptune should be recognizable thanks to its bluish color.
With a telescope, trying to resolve Neptunes into a disk (instead of just a point of light) will be more difficult than it is with Uranus. Youre going to need at least a four-inch telescope with a magnification of no less than 200-power, just to turn Neptune into a tiny blue dot of light.
| About Your Tour Guide
Starry Night software maps the sky from your location. In this video, learn what one noted astronomer thinks of it. 
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Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for The New York Times and other publications, and he is also an on-camera meteorologist for News 12 Westchester, New York.
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