Is There a Possibility of Life on Uranus?

Uranus

The planet Uranus, the seventh planet from the sun, was so hard to find in part because it is a whopping 1.8 billion miles away from Earth. It is actually the third-largest planet in our solar system and would fit 4 Earths inside its mass. Sir William Herschel was the first to discover Uranus in March 1781 using a telescope. But his sighting made him conclude it was a dim comet. It is hard to see with the naked eye and moves very slowly across the sky. It was not until years later that it was upgraded to the status of a planet. Voyager 2 passed Uranus within 81,500 kms in 1986 and took a staggering photo of Uranus (seen above). This photo made the scientific community excited because it looked so fertile and verdant. Surely the search for a planet similar to Earth (the small blue dot) had been successful. Some certainly thought this was the best possibility yet judging by appearances.

Well let’s investigate.

FACTS ABOUT URANUS

Uranus was too dim to have been seen by the ancients. Herschel tried to have his discovery named “Georgian Sidus” after King George III. The name Uranus was suggested by astronomer Johann Bode. The name comes from the ancient Greek deity Ouranos. The only planet to be named after a Greek god and not a Roman god.

Uranus turns on its axis once every 17 hours, 14 minutes. The planet rotates in a retrograde direction, opposite to the way Earth and most other planets turn. Uranus makes one trip around the Sun every 84 Earth years. During some parts of its orbit one or the other of its poles point directly at the Sun and get about 42 years of direct sunlight. The rest of the time they are in darkness. Uranus is often referred to as an “ice giant” planet. Like the other gas giants, it has a hydrogen upper layer, which has helium mixed in. Below that is an icy “mantle”, which surrounds a rock and ice core. The upper atmosphere is made of water, ammonia and the methane ice crystals that give the planet its pale blue colour. Uranus hits the coldest temperatures of any planet. With minimum atmospheric temperature of -224°C Uranus is nearly coldest planet in the solar system. While Neptune doesn’t get as cold as Uranus it is on average colder. The upper atmosphere of Uranus is covered by a methane haze which hides the storms that take place in the cloud decks.

Uranus has two sets of very thin dark coloured rings. The ring particles are small, ranging from a dust-sized particles to small boulders. There are eleven inner rings and two outer rings. They probably formed when one or more of Uranus’s moons were broken up in an impact. The first rings were discovered in 1977 with the two outer rings being discovered in Hubble Space Telescope images between 2003 and 2005. Only one spacecraft has flown by Uranus. In 1986, the Voyager 2 spacecraft swept past the planet at a distance of 81,500 km. It returned the first close-up images of the planet, its moons, and rings. Saturn is the least dense planet in our celestial family, Uranus is not far behind. Most of its mass is made up of an icy dense fluid of water, ammonia, and methane. Like Saturn, Jupiter and Neptune, Uranus is a gas giant, and does not have a solid surface. Neither does it have a super hot core arising from super-heated metals.

ORBIT & ROTATION

One day on Uranus takes about 17 hours (the time it takes for Uranus to rotate or spin once). Uranus makes a complete orbit around the Sun (a year in Uranian time) in about 84 Earth years (30,687 Earth days). The unique tilt of Uranus causes the most extreme seasons in the solar system. For nearly a quarter of each Uranian year, the Sun shines directly over each pole, plunging the other half of the planet into a 21-year-long, dark winter. Uranus is also one of just two planets that rotate in the opposite direction than most of the planets (Venus is the other one), from east to west.

The tilt of Uranus is so pronounced 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. So, 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. Thanks to its sideways turn, Uranus has some wild seasons, with the sun blazing across each pole while the opposing side lingers in the pitch blackness of space. And that’s not the only strange thing about its spin. The retrograde rotation plays havoc with Uranus’ magnetosphere, the magnetic field enveloping the gaseous world. It’s tipped nearly 60 degrees from the axis of rotation and offset by a third of its mass. That sets the planet’s auroras out of line, making them appear far from the poles, unlike those on Earth. It also creates an unstable magnetic field.

TEMPERATURE

Uranus is the seventh 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. However, this does not prevent Uranus from being colder than Neptune. Whereas the former 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 dip 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.

ATMOSPHERE AND WEATHER

Uranus owes its vibrant blue-green hues not from unusual oceans but from an upper atmosphere flush with methane which absorbs the sun’s red light and scatters blue light back to our eyes. The rest of planet’s atmosphere is largely made of hydrogen and helium, with small amounts of ammonia, water, carbon dioxide, carbon monoxide and methane. Trace amounts of hydrogen sulphide such that should you be able visit this distant place without a spacesuit, the planet would smell like rotten eggs. Uranus maybe photogenic but it belies that fact that its atmosphere is a toxic mixture of gases which don’t support life as we know it. While Voyager 2 saw only a few discrete clouds, a Great Dark Spot and a small dark spot during its flyby in 1986, more recent observations reveal that Uranus exhibits dynamic clouds as it approaches equinox, including rapidly changing bright features. Uranus’ planetary atmosphere, with a minimum temperature of 49K (-224.2 degrees Celsius) makes it even colder than Neptune in some places. Wind speeds can reach up to 560 miles per hour (900 kilometers per hour) on Uranus. Winds are retrograde at the equator, blowing in the reverse direction of the planet’s rotation. But closer to the poles, winds shift to a prograde direction, flowing with Uranus’ rotation.

Therefore Earth has a midnight sun in summer at its poles, and a long polar night in winter. But those dark and bright times at Earth’s poles affect a smaller part of our planet, and don’t last nearly as long as they do on Uranus. For two 21-year seasons on Uranus – the winter-summer seasons – the poles of Uranus are pointed (more or less) either toward the sun, or away from it. During Uranus’ winter-summer season, the winter side of the planet never sees the sun. It doesn’t see the sun for 21 long years. Meanwhile, the summer side of the planet has continuous daylight. That’s a long polar night, and a long midnight sun!

Now think about the other two seasons – spring and autumn – on Uranus. At those seasons, Uranus is oriented in its orbit so that sunlight strikes its equatorial region. At those seasons, the length of a day on Uranus comes into play. Uranus spins on its axis about every 17 hours, 14 minutes. So its day-night cycle lasts that long. During the planet’s spring and fall, a large percentage of the planet has day and night – a shift between daylight and darkness – again and again about every 17 hours. So, for much of the planet, where there had been continuous day or continuous night lasting decades on an earthly scale, now there’s a fast change between day and night.

That change causes dramatic shifts in the cloud pattern on Uranus, as earthly astronomers have now seen. Uranus has been visited by one spacecraft – the NASA spacecraft Voyager 2 in 1986. When Voyager 2 passed Uranus, this world was in its northern hemisphere summer, and Voyager saw Uranus as blue and featureless. As the years have passed since Voyager 2’s flyby of Uranus – as technologies for observing Uranus from Earth (or Earth-orbit) have become more powerful – and as Uranus moved in its 84-year orbit around the sun – we’ve seen the seasons on Uranus change.

In the years after the Voyager 2 flyby, the planet came out of the grip of its decades-long winter/summer season. Its northern hemisphere autumn equinox occurred in 2007; that’s when the sun was shining above Uranus’ equator. Sunlight had begun reaching some latitudes for the first time in years. The light and warmth in the atmosphere triggered gigantic storms comparable in size to North America (but with temperatures of 300° below zero), visible as bright spots in the planet’s atmosphere. Around that time, observers on Earth saw more clouds in the atmosphere of Uranus – and bands encircling the planet that had changed in size and brightness – as sunlight struck parts of the planet for the first time in decades. They saw a dark spotand more bright spots, which earthly observers were able to follow for years. The dark spot on Uranus is similar to the Red Spot on Jupiter andmarks fierce storms which can last for years.

RINGS

When it comes to ring systems, Saturn’s are the most famous. In addition to be colourful and far-reaching, they are also highly visible. One could spot them using nothing more than a backyard telescope. But in truth, 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 micrometres to a fraction of a meter – hence why they are not nearly as discernible as Saturn’s. 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 kilometres in width. The rings are probably quite young, and are not believed to have formed with Uranus. 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.

MOONS

Like all of the giant planets, Uranus has its share of moons. At present, astronomers have confirmed the existence of 27 natural satellites. But for the most part, these moons are small and irregular. If you were to add up all of their masses, they would still be less than the half the mass of Triton, Neptune’s largest moon. However, unlike Triton, Uranus’ larger moons are all believed to have formed from an accretion disk of space detritus that surrounded the planet, rather than being captured objects.

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 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.

Now let’s sum up the conditions related to the likelihood of Life on Uranus

I believe any thinking person would conclude that Uranus is the least likely for all the planets in our Solar System for life to exist of any sort. There is no solid surface on Uranus to enable a space ship of any sort to land. Neither would it be possible to build a house or structure on Uranus to protect life. In fact scientist theorize that any metal structure coming within the atmosphere of Uranus would be destroyed.

There is no oxygen to breathe and in fact the make-up of the atmosphere would be toxic to human life and to plant life as we know it here on Earth. Besides which having darkness for 21 years across the planet would certainly count against any plants surviving and no oxygen therefore no cycles of photosynthesis from the Sun’s light and heat. it seems a lost cause. Winds of up to 900 kph would be detrimental to say the least.

You might imagine some perfect place inside Uranus, where the temperature could support life. The problem is that the pressures inside Uranus are enormous and would crush life. The other problem is that life on Earth requires sunlight to provide energy. There’s no process inside Uranus, like volcanism on Earth, that would give life inside the planet a form of energy.

What appeared to be a distinct possibility of another planet capable of supporting life with the publishing of the Voyage 2 photo has evaporated. Yet despite the mass of evidence to contrary when asked if there is a possibility of life on Uranus, scientists make such comments as “it appears highly unlikely but we live in hope.” “Maybe, but probably not.”

Forgive me if I am deluded. I would say it takes quantum amounts of faith in science and present observable processes being the key to understand the origins of life (translation for Donald Trump – oranges) . Looking at all of this information I have gathered leads me to one conclusion. God created the heavens and the earth and placed it perfectly to sustain life for mankind whom He designed to live on the planet he made for us. Then like the creatures He created, He threw in some planets to play with our minds but ultimately to help us realise the “small blue dot “ that we call home is perfect for our habitation. There is no other.

But we do have one more planet to assess. I am sure you are thinking like me – fat chance. After looking at Neptune I will return us to Earth and point you to other factors which make Earth the home it is for us.