Astro Bob: How to find the planet Yoo-RAIN-us
On Wednesday, Nov. 9, Earth and Uranus will be at their closest for the year. All you need is a pair of binoculars to find and track this distant blue world.
When it comes to the seventh planet many of us feel awkward pronouncing its name. I grew up with yoo-RAIN-us because the word anus simply wasn't in common usage at the time. How I miss those days of innocence. As I grew older and wiser in the ways of the world I quietly switched to the alternative "YOUR-in-us" to avoid knowing looks and my own temptation to drop one-liners.
Now I'm back to using the older pronunciation because equivocating just takes too much energy. To back me up I direct your attention to Exhibit A — uranium. Element 92 was named after the planet. Say the word out loud, and you'll understand my point.
Not matter how you vocalize it, Uranus is certainly a strange planet. It rotates around the sun on its side tilted 98° from vertical. Astronomers hypothesize that a cataclysmic collision between a young protoplanet roughly twice the size of Earth literally tipped Uranus over.
Debris from the mashup could still be trapping heat rising from Uranus's core and account the planet's frigid atmospheric temperature which hovers around 350° below zero (-212° C). Some of its 27 known moons may even be shrapnel formed from material blasted into nearby space that later coalesced into spheres through self-gravity.
One year on Uranus lasts 84 Earth years — the time it takes the remote planet to circle the sun at an average distance of 1.8 billion miles (2.9 billion km). Light leaving the cold, cloudy world at 186,000 miles per second (300,000 km/sec) must travel 2.6 hours before reaching our eyes.
Uranus glows blue-green from methane (which absorbs red light and reflects back blue) and is almost exactly four times as big as Earth. That makes it the next largest planet after Saturn and third biggest overall. But its great distance makes it look no different from a star when viewed with the naked eye or binoculars.
A telescope magnifying 100x or more will reveal a tiny, bluish disk about the size of a pinhead. With a 10-inch or larger telescope, you can seek the planet's two largest and brightest moons, Titania and Oberon.
Now's the best time to see the remote ice giant, since it reaches opposition on Nov. 9, when it's closest to Earth and brightest. Under dark, moonless skies it's even visible without optical aid. Binoculars make it easily accessible even from relatively light-polluted skies.
Although Uranus resides in an out-of-the-way corner of Aries this season, it's relatively easy to find if you start at the Pleiades (Seven Sisters), a bright, dipper-shaped star cluster that's well-placed for viewing in the eastern sky starting around 8 p.m. local time.
The wide-view map at the top of this page shows the planet's general location and direction. Use it to get oriented, then switch to the more detailed chart. I added arrows with a suggested "route" starting at the Pleiades. From there, slide right and star-hop to two convenient "way stations," the Trapezoid and Triangle. Once you've found the Triangle, look a little below it for a "star" at the position(s) shown on the map. That's Uranus!
Of course, you can choose a different path to the target. Either way, if you drop by for a look every week or two you'll see Uranus inch westward (up and to the right when facing east). Seeing movement will guarantee that you're looking at the real thing. Stars are fixed in position relative to each, but planets move — one of the things that make them so cool to observe.