SEE URANUS THIS WEEK
How to see Uranus in the night sky
(without a telescope) this week
NASA’s Voyager 2 spacecraft captured this image of the planet Uranus on Dec. 18, 1986. (Image credit: NASA/JPL-Caltech)
Just how many planets are visible without a telescope?
Not including our own planet, most people will answer “five” (Mercury, Venus, Mars, Jupiter and Saturn).
Those are the five brightest planets,
But in reality, there is a sixth planet that can be glimpsed without the aid of either a telescope or binoculars.
That sixth planet is the planet Uranus.
This week will be a fine time to try and seek it out,
Especially since it is now favorably placed for viewing in our late-evening sky and the bright moon is out of the way.
SEE URANUS THIS WEEK
This sky map shows where Uranus will be located around midnight on Sept. 13-14, as seen from New York City.
Look for it in the constellation of Aries, the ram.
Of course, you’ll have to know exactly where to look for it.
Astronomers measure the brightness of objects in the night sky as magnitude.
Smaller numbers indicate brighter objects, with negative numbers denoting exceptionally bright objects.
But Uranus is currently shining at magnitude +5.7, relatively dim on the scale;
Barely visible by a keen naked eye on very dark, clear nights.
It is currently located within the constellation of Aries, the Ram,
About a dozen degrees to the east (left) of the brilliant planet Mars.
It’s already one-third up from the eastern horizon by 11:30 p.m.
local daylight time and will reach its highest point — more than two thirds up from the southern horizon — just before 4 a.m.
It is best to study the accompanying chart first, then scan that region with binoculars.
Using a magnification of 150-power with a telescope of at least three-inch aperture,
you should be able to resolve it into a tiny, blue-green featureless disk.
An icy, cold world
This week Uranus is about 1.771 billion miles (2.851 billion kilometers) from Earth (only Neptune is farther away).
It takes 84.4 years to orbit the sun.
The planet has a diameter of about 31,518 miles (50,724 km), making it the third-largest planet,
And according to flyby magnetic data from Voyager 2 in 1986, has a rotation period of 17.23 hours.
At last count, Uranus has 27 moons,
All in orbits lying in the planet’s equator in which there is also a complex of nine narrow, nearly opaque rings, which were discovered in 1978.
Uranus likely has an icy, rocky core,
Surrounded by a liquid mantle of water, methane and ammonia, encased in an atmosphere of hydrogen and helium.
In fact, Uranus has the coldest atmosphere of any planet in the solar system,
With a minimum temperature of -371 degrees Fahrenheit (minus 224 degrees Celsius).