Uranus? You Betcha!

Uranus has 27 moons, a half dozen of which are shown in this photo taken in 2002 by the VLT in the Atacama Desert of northern Chile. Credit: ESO
Uranus has 27 moons, a half dozen of which are shown in this photo taken in 2002 by the VLT in the Atacama Desert of northern Chile. Instead of assigning names from Greek mythology, John Herschel (son of the planet’s discoverer William Herschel) named the moons after magical spirits in English literature. Uranus also possesses a system of at least 13 faint, dark rings. Credit: ESO

Not many people pay attention to the 7th planet. Sure, sure we have lots of fun with its name, but have you have stepped out at night to see it with your own eyes? Several nights ago under a dark sky, I could faintly see Uranus just by looking up at the right spot in Pisces the Fish, its haunt for the past few years. No binoculars, no telescope. How many thousands of eyes over the centuries must have run across this point of light? Not a one knew it stood apart until English astronomer William Herschel “put it on the map” in 1781.

We start easy on our quest to find Uranus, beginning with the Square of Pegasus. Shoot a diagonal line across the Square downward to the east and you'll arrive at three faint stars in a row:
We start easy on our quest to find Uranus, beginning with the Square of Pegasus. Shoot a diagonal line across the Square downward to the east and you’ll arrive at two fainter 4th magnitude stars, Delta (right) and Epsilon Piscium. Center your binoculars on the pair and Uranus will be in your field of view a short distance (2°) to the south of Epsilon. Its position is shown for mid-November. Source: Stellarium

Dark skies were the norm hundreds of years ago. Now they’re the exception. That’s why I don’t expect you to just walk out and find Uranus. But the good news is a pair of binoculars will do the job, and the planet is ideally placed for viewing during the early evening hours.

Start with the giant Square of Pegasus, a big, connect-the-dots square of stars high in the southeastern sky around mid-month. Next, shoot a diagonal line through the Square downward into the dim constellation Pisces to the two faint stars Epsilon and Delta Piscium. Uranus lies a short distance directly below Epsilon.

North is up in this wide-field binocular view of Uranus and environs. Its path is shown Nov. 15 through early April 2016. I've labeled several stars with their magnitudes. Uranus is magnitude +5.7 is slightly brighter than the typical naked eye limit. Created with Chris Marriott's SkyMap
North is up in this wide-field binocular view of Uranus and environs. Its path is shown Nov. 15 through early April 2016. I’ve labeled several stars with their magnitudes. Uranus, at magnitude +5.7, is slightly brighter than the typical naked eye limit. The three stars at top — Zeta, Epsilon and Delta Piscium — are all dim naked eye stars. Created with Chris Marriott’s SkyMap

It looks just like a star, similar to several in its neighborhood. That’s why the detailed map will help you to figure out exactly which is which.

Uranus moves westward until the day after Christmas, then resumes its normal eastward motion. All the outer planets take a several-month-long side jaunt to the west around the time they’re closest to Earth. It’s called retrograde motion because the planet appears to stop and move “backwards” (west) in retrograde. What’s really happening? The faster Earth passes the slower, more distant planet, making it look like it’s falling behind. We see the same thing happen when passing a car on the freeway – as we speed by, it temporarily appears to travel backwards.

Only after 84 years would a hypothetical Uranian citizen be able to celebrate their 1st birthday. Uranus rotates on its side unlike the other planets with each of its four seasons lasting 21 years. It will be fall in the planet's northern hemisphere until the 2028 winter solstice. Credit: Nature of the Universe with additions by Bob King
Only after 84 years would a hypothetical Uranian citizen be able to celebrate their 1st birthday. Uranus rotates on its side unlike the other planets, with each of its four seasons lasting 21 years. It will be fall in the planet’s northern hemisphere until the 2028 winter solstice. Credit: Nature of the Universe with additions by Bob King

While binoculars will only show the planet as a “star”, a small telescope magnifying around 100x reveals a tiny disk, exposing its true identity. Owners of telescopes in the 10-inch and larger range may want to seek out the planet’s two brightest moons, Titania and Oberon. Although nearly buried in Uranian glare, a night of steady air coupled with magnifications of 200x or higher will coax each into view. To find out where they are at any time on any night, launch Sky and Telescope’s  Uranus Moon Finder.

Uranus and Earth compared. Uranus has an atmosphere of hydrogen and helium with clouds of ammonia and methane. It's the methane that gives the planet its characteristic aqua color. Credit: NASA
Uranus and Earth compared. Uranus has an atmosphere of hydrogen and helium with clouds of ammonia and methane. It’s the methane that gives the planet its characteristic aqua color. Credit: NASA

Close-up photos taken by the Voyager 2 spacecraft during its January 1986 flyby of the planet showed mostly a bland blue sphere, but Uranus is anything but boring. Here are 8 fast facts to help illuminate this faraway world:

  •  Twice as far from the sun (1.8 billion miles) as the planet Saturn. If you could fly there in a transcontinental jet cruising along at 550 mph, it would take 373 years to arrive. Even Voyager 2 needed 8 1/2 years to make the journey.
  •  Its axis is tilted 98°, so Uranus orbits the sun on its side with its poles periodically facing Earth.
  •  Uranus looks blue because methane in its atmosphere absorbs red light. While its atmosphere is primarily hydrogen and helium, it has more methane than Jupiter or Saturn.
  •  Uranus is the first planet discovered with the telescope. English astronomer William Herschel stumbled across it with his homemade 6.2-inch reflecting telescope on March 13, 1781.
  • Each season on Uranus lasts 21 years. Due to its sideways rotation, each pole is plunged into complete darkness for 21 years of every orbit around the sun. Brrrr!
  • Uranus is an “ice giant”. Eighty percent of the planet’s mass is made up of a hot, dense fluid of water, methane and ammonia with a rocky core at center.
  • The average temperature is -350°F (-212°C) compared to clement Earth’s 61°F (16°C) average.
  • A day on Uranus lasts 17 hours and 14 minutes, hardly enough time to eat, sleep, work and do the grocery shopping.

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