Recently, I had a unique opportunity to see one of the rarely-viewable (from Earth) planetary neighbors of Earth . . . Planet Uranus.
Yes, I know that the planet has received a bit of a rap from an increasingly smart-alec pop-Earth culture. I believe this is the greatest reason that, in the popular mind, most people tend to overlook the astronomical and scientific significance of this planet.
THE PLANET URANUS AND SCIENTIFIC FACTS
Before attempting to find the planet, I researched some of the greatest characteristics of this large, pale-aquamarine planetary neighbor in our Solar System. I wanted to know for certain that Planet Uranus had more to it’s name than an ongoing, crude jokes.
Uranus is the 7th planet from the Sun, orbiting at a distance of 2.88 billion km. But it’s still much closer than Neptune, which averages a distance of 4.5 billion km from the Sun. It is one of the “Jovian Planets”, the large planets with gaseous atmospheres that consists of Jupiter, Saturn, and Neptune.
Uranus is the 3rd largest planet in terms of size, the 4th in size in terms of mass, and one of the least dense objects in our Solar System. It has 63 times the volume of Earth by comparison.
It is also the only planet in the Solar System that takes it name from Greek (rather than Roman) mythology. The astronomical community settled on the name Uranus – the Latinized version of the Greek god of the heavens, Ouranos. In today’s culture, Ouranos could have saved the planetary name-calling jokes from becoming so wide spread.
Uranus is the coldest planet in the Solar System even though Neptune is much further away, However, this does not prevent Uranus from being colder than Neptune. It experiences an average temperature of 72 K (-201 °C/-330 °F), reaching a low of 55 K (-218 °C/-360 °F).
In contrast, the temperatures at the cloud tops on Uranus (which is defined as “surface temperature” for gas giants) averages 76 K (-197.2 °C/-323 °F), but can go as low as 47 K (-226 °C/-375 °F). This is due to the fact that, unlike the other large planets in the Solar System, Uranus actually gives off less heat than it absorbs from the Sun.
While the other large planets have tremendously hot cores, which radiate infrared radiation, Uranus’ core cooled down to the point that it no longer radiates much energy.
Uranus orbits the Sun on its side. All of the planets in the Solar System rotate on their axis, with a tilt that’s similar to the Sun. In many cases, planet’s have an axial tilt, where one of their poles will be inclined slightly towards the Sun. For example, the axis of the Earth’s rotation is tilted 23.5-degrees away from the Sun’s plane. Mars is similar, with a tilt of about 24 degrees, which results in seasonal changes on both planets.
But the axial tilt of Uranus is 99 degrees! All the planets look a bit like spinning top as they go around the Sun, but Uranus looks more like a ball rolling in a circular pattern. A day Uranus (that is, the time it takes for the planet to completely) is only about 17 hours long (versus Earth’s 24 hour rotation).
A Season on Uranus lasts one long day 42 Earth-years versus the seasons of Earth that are only around 3 months (or 0.25 Earth-years). But the sideways tilt of Uranus great enough that one pole or the other is usually pointed towards the Sun. This means that a day at the north pole of Uranus lasts half of a Uranian year – 84 Earth years. As an example, if you could stand on the north pole of Uranus, you would see the Sun rise in the sky and circle around for 42 years. By the end of this long, drawn-out “summer”, the Sun would finally dip down below the horizon. This would be followed by 42 years of darkness, otherwise known as a single “winter” season on Uranus.
Uranus is the second-least dense planet. The least dense planet in the Solar System is Saturn. With a mean density of 0.687 g/cm3, Saturn’s body is actually less dense than water (1 g/cm³). This means that the planet would float in a pool, provided it were roughly 60,000 km wide. With a mean density of 1.27 g/cm3, Uranus has the second-lowest density of any planet in the Solar System. Basically, despite the fact that Uranus is 14.5 times as massive as the Earth, its significantly lower density means that you would only experience about 89% the force of gravity, if you could stand on Uranus’ cloud tops.
Uranus has rings. Saturn’s rings are the most famous and visible. One could spot them using nothing more than a backyard telescope (which I did several months ago in this article). But ALL the gas and ice giants have their own ring systems, and Uranus’ is the second most dramatic set of rings in the Solar System. However, these rings are composed of extremely dark particles which vary in size from micrometers to a fraction of a meter – hence why they are not nearly as visible. Thirteen distinct rings are presently known, the brightest being the epsilon ring. And with the exception of two very narrow ones, these rings usually measure a few kilometers in width.
The matter in the rings may once have been part of a moon (or moons) that was shattered by high-speed impacts. From numerous pieces of debris that formed as a result of those impacts, only a few particles survived, in stable zones corresponding to the locations of the present rings.
The atmosphere of Uranus contains “ices” due to the extreme cold. The third-most-abundant component of Uranus’s atmosphere is methane (CH), which is what accounts for Uranus’ aquamarine color. There are also trace amounts of other hydrocarbons, such as ethane, acetylene, methylacetylene, and diacetelyne – all of which are believed to be the result of methane interacting with solar ultraviolent radiation (aka. photolysis). There are confirmed traces of water, ammonia, carbon dioxide, carbon monoxide, and hydrogen sulfide within the layers of Uranus’ atmosphere.
Compared to Jupiter and Saturn seems average (with it’s light and uniform aquamarine color). It’s easy to see the swirling clouds and eddies in Jupiter and Saturn’s atmospheres. But advanced instruments can examine planets through other wavelengths (i.e. infrared). In 1986, the Voyager 2 spacecraft swept past the planet at a distance of 81,500 km, becoming the only spacecraft to “visit” as closely. It returned the first close-up images of the planet, its moons, and rings. It has been determined that Uranus has powerful zonal winds within its atmosphere that can reach up to 250 m/s (900 km/h, 560 mph), and can generate anticyclonic storms like Jupiter’s Great Red Spot. It also has cloud patterns that differ between hemispheres, some of which last for mere hours while others can persist for years or decades.
Uranus has many moons (not unlike Jupiter, Saturn, and Neptune). Astronomers can confirm 27 separate moons the planet’s orbit. But for the most part, these moons are small and irregular. The largest moons of Uranus are (in order of size) Miranda, Ariel, Umbriel, Oberon and Titania. These moons range in diameter and mass from 472 km and 6.7 × 1019 kg for Miranda to 1578 km and 3.5 × 1021 kg for Titania. Each of these moons are dark in color. Ariel is the brightest while Umbriel is the darkest. Each one is comprised of roughly equal amounts of rock and ice, except for Miranda which is made primarily of ice, which may include ammonia and carbon dioxide, while the rocky material is believed to be composed of carbonaceous material.
Uranus was the first planet discovered after the invention of the telescope. It was first recorded in 1690 by John Flamsteed, who thought it was a star in the constellation Tauri (e.g. it was cataloged as the star 34 Tauri in the Taurus constellation). But Sir William Herschel 1781’s observations that helped confirmed that it was a planet.
It IS possible to see Uranus without a telescope, and has actually been spotted many times in the past by ancient and pre-modern astronomers. With a visible magnitude of 5.3, Uranus is just within the brightness scale that a human eye can detect. Unfortunately, you’d need to ensure the night sky was very dark, was as free of light pollution and clouds as possible.
You also have to know exactly where to look, but there’s a way to do this (e.g. see the image above for the Sky Guide locator app image).
THE TELESCOPE SETUP
To see Uranus the closest, I chose the 10mm eyepiece to increase the power. In my case, I again used my small traveling telescope which is a Celestron Travel Scope 70.
I then queried the SkyGuide app (that I’ve used for the past 2 years) to see when and where Uranus would rise during the evening hours. On October 22, it was positioned near constellations Aries, Pisces, and Andromeda, just behind Saturn visible trajectory by over hour (and visible at the same time as well). Everything was ready once again . . .
GETTING A CLEAR VIEW
Around 9:30 PM Arizona time, I took a look. With the telescope, I could very faintly see Uranus as a lightly tinged bluish and light green “star” among the others. As I’m in the a Phoenix metro area, the telescope helped.
The upper left shows a similar image to what I saw, but the iPhone I had was not able to zoom in clearly through the scope lens. The bottom image would be closer to I would have seen if I had a stronger telescope (but likely more blurry). The blurring is to be expected given atmospheric conditions like temperature, humidity, faint clouds, etc. I’ve lately been looking into scope options. 🔭💫
Even if you’ve missed the October 2019 Opposition date, there should still be plenty of great opportunities to see Saturn throughout the rest of 2019z You can also still get great views of Jupiter and Saturn like previous months )although slightly further away as Earth moves on it’s orbital course around the Sun). As before, a small telescope similar to what was used here or go down to an observatory that might be close to you.
For The Great Galactic Space Gimmick, I’m Gimmick Commander Ben Faltinowski. 🔭 ⭐️
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DISCLAIMER: The images and information cited herein came from various sources on the internet and are used here strictly for discussion, educational purposes, and for promotion of astronomy and the Space Program. Also, Celestron telescopes were mentioned as the manufacturer of the small telescope that was used for this article, which can be construed as a positive review of this product. No royalties were collected or sought for this article, and this article is free to the public. It is believed that this constitutes fair use.