Be sure to look up Sunday night: Uranus will twinkle in the night sky gently lit by the crescent Moon. Just below the dimly lit crescent moon, which will be illuminated approximately 7%, Uranus will be there twinkling in the western sky, right after dark. The best time to see Uranus is Sunday night; but don’t wait too long to peer into the night sky; Uranus will set below the horizon not long after sunset, so it’s best to view it within an hour of sunset. Uranus won’t be visible in the night sky until this fall when it’ll reappear in October.
Uranus will appear just below and to the right of the Moon as a blue-green dot; using binoculars or a telescope will improve the view.
Uranus is a mysterious place, with scientists learning more and more about the distant planet each year. Recent research has uncovered that Uranus smells and squirts X-Rays and it appears slushy balls move about in the planet’s atmosphere.
Researchers using a telescope on Hawaii in 2018 were able to determine that Uranus smells with an atmosphere rich in rotten egg smelling hydrogen sulfide; another observatory on Hawaii combined with satellite data confirmed that the mysterious planet also squirts x-rays.
Using technology made possible with a telescope on Hawaii’s Big Island, scientists have been able to identify the smelly gas there, setting the stage for other interesting discoveries in our Universe and beyond. Prior to this point, the composition of Uranus’ atmosphere has never been unambiguously identified. It was widely assumed to be composed primarily of either ammonia or hydrogen sulfide (H2S) ice. In a paper published in April 2018 in Nature Astronomy, scientists describe how they confirmed the hydrogen sulfide in the atmosphere there.
“If an unfortunate human were ever to descend through Uranus’ clouds, they would be met with very unpleasant and odiferous conditions,” study lead author Patrick Irwin, of Oxford University in England, said in a statement. “Suffocation and exposure in the negative 200 degrees Celsius (minus 328 degrees Fahrenheit) atmosphere, made of mostly hydrogen, helium, and methane, would take its toll long before the smell.”
In a report published in the Journal of Geophysical Research, scientists have determined that Uranus is also emitting x-rays. In this new study, researchers used Chandra satellite observations taken in Uranus in 2002 and then again in 2017. They saw a clear detection of X-rays from the first observation, just analyzed recently, and a possible flare of X-rays in those obtained fifteen years later. Scientists were able to superimpose an optical image from the Keck-I Telescope, captured in another study in 2004, with the observations nearly at the same orientations as the satellite imagery, to help visualize what is happening. The Keck-I Telescope is located near the Gemini North telescope on Mauna Kea too.
Beyond being a smelly, X-Ray emitting planet, scientists now believe balls of slush are harboring ammonia in the planet’s atmosphere. A study presented by Tristan Guillot at the Europlanet Science Congress (EPSC) 2021 shows that mushballs could be highly effective at carrying ammonia deep into the planet’s atmospheres, hiding the gas from detection beneath relatively opaque clouds.
Recent remote observations at infrared and radio wavelengths have shown that Uranus lacks ammonia in its atmosphere compared to the other giant planets in our solar system. This is surprises scientists because beyond ammonia, they are otherwise rich in other compounds that make Uranus especially smelly.
Guillot, a researcher at the CNRS, Laboratoire Lagrange in Nice, France, turned to a recent discovery at Jupiter for a possible answer to the puzzle. “The Juno spacecraft has shown that in Jupiter, ammonia is present in abundance, but generally much deeper than expected—thanks to the formation of mushballs. I show that what we have learned at Jupiter can be applied to provide a plausible solution to this mystery at Uranus and Neptune,” said Guillot.
The Juno observations of Jupiter have shown that ammonia-water hailstones can form rapidly during storms. Models indicate that these mushballs in Jupiter may grow to weights of up to 2 pounds or more, which is greater than the weight of the largest hailstones found on Earth. As they plunge downwards, they transport ammonia very efficiently to the deep atmosphere, getting locked-up beneath the cloud base.
“Thermodynamic chemistry implies that this process is even more efficient in Uranus and Neptune, and the mushball seed region is extended and occurs at greater depths,” said Guillot. “Thus, ammonia is probably simply hidden in the deep atmospheres of these planets, beyond the reach of present-day instruments.”
While it’s unlikely humans will ever be able to visit this smelly, mushball-filled atmosphere, the idea that the sophisticated observing equipment that scientists have at their disposal to unlock mysteries on far away planets excites and titillates many. And such discoveries may help unlock mysteries on Earth and nearby planets that humans could be exploring in the coming years.