Just a short while ago, our understanding of the universe was limited to nine planets within our own solar system (before Pluto was reclassified). However, in the past few decades, we have witnessed a remarkable expansion of our knowledge as thousands of planets have been discovered orbiting stars other than our Sun. With each passing month, more confirmations add to this growing tally. Among these discoveries are worlds so incredibly unique and alien that even the most imaginative science fiction writers would struggle to envision them. In this week’s listicle, we embark on a journey to explore ten of the most breathtaking and awe-inspiring skies found in the vast expanse of our Universe.
#1. Proxima b
An artist’s impression of the sky as seen from Proxima b during the day time. In the background are the two Sun-like stars Alpha Centauri A and B.
25 trillion miles (40 trillion km) away lies our closest stellar neighbour, the red dwarf star of Proxima Centauri. This relatively tiny star, being only about 12% as massive as our own, hosts a rocky planet slightly larger than Earth. Although likely not habitable, contrary to popular thinking, the view from planet Proxima b would be quite otherworldly to say the least, largely because Proxima Centauri is likely part of the Alpha Centauri binary star system. Not only would you see the deep red ball of the alien sun in the daytime; you’d also see two other distant suns in the sky.
#2. Pluto
Based on images and data gathered by NASA’s New Horizons probe, this artist’s impression shows the barren surface and alien skies of Pluto.
The lonely dwarf planet of Pluto, with its selection of at least five moons, lies between 30 and 50 times further away from the Sun than Earth. As such, it’s a dark world, but not as gloomy as you might think. In fact, although the Sun looks much like a star from the surface in terms of size, it’s still hundreds of times brighter than the full Moon as seen from Earth. Even more amazingly, the hazy particles in Pluto’s tenuous atmosphere scatter the sunlight in such a way that there’s even a deep blue tinge to the sky.
#3. Phobetor
An artist’s impression of the sky as seen from the surface of a pulsar planet, such as Phobetor, Draugr or Poltergeist.
Phobetor is a planet that shouldn’t exist. This planet, about four times more massive than Earth, accompanies the worlds of Draugr and Poltergeist in orbit of Lich (PSR B1257+12), the undead husk of a star left behind after a supernova explosion billions of years ago. Instead of a sun like our own, the daytime skies of Phobetor are dominated by a rapidly spinning light accompanied by spectacular and eternal auroras. This stellar remnant is a pulsar, a tiny, extremely dense ball of neutrons that weighs 40% more than our Sun, yet is no bigger than Central Park.
#4. The Moon
One of the most famous photos ever taken, Earthrise was shot in 1968 during the Apollo 8 mission to the Moon.
Easily one of the most beautiful sights in the Universe is the view of our own world as seen from the surface or in orbit of the Moon, a privilege that, so far, only 24 people have enjoyed. The so-called ‘Earthrise’ picture was taken on Christmas Eve of 1968, and it was one of the photos that truly changed the world, bringing the wonders of space exploration closer to the masses. Thanks to a complete lack of atmospheric or light pollution, the Earth appears to lunar-based observers as a crystal-clear marble dominating the skies.
#5. Kepler-186f
A simulated view of the sky as seen from the surface of Kepler-186f, assuming it has an Earth-like atmosphere.
550 light-years away lies one of the most potentially habitable worlds that science has so far discovered, Kepler-186f. Only slightly larger than Earth, this rocky exoplanet lies comfortably within the habitable zone but, orbiting a red dwarf star, its skies would appear very different to our own. The small, dim sun would likely give the sky a deep reddish hue, lending to spectacular blood-red sunsets, albeit depending on the as-yet undetermined atmospheric conditions. Nonetheless, it may just be that our distant descendants will look up at this alien sky and call it home.
#6. Europa
While the surface of Europa is incredibly cold and airless, several miles beneath your feet exists a vast ocean of liquid water.
With its vast subsurface ocean, Jupiter’s moon Europa is one of the most promising places in the solar system for finding extraterrestrial life. While its icy surface is as hard as granite in temperatures of −171 °C, the view would nonetheless be one of the most splendid of all. Imagine the enormous globe of Jupiter, some 25 times the apparent diameter of the Moon as seen from Earth, dominating the skies. Combine that with the spectacular geysers of water vapour erupting from the underground ocean, and you’ve got a pretty otherworldly view to gaze upon.
#7. Small Magellanic Cloud
Taken from Chile’s Atacama Desert, you can see the Large and Small Magellanic Clouds to the left.
Known since ancient times, the Small Magellanic Cloud is one of the closest of at least 50 satellite galaxies that are gravitationally bound to our own Milky Way. Although no planets have yet been discovered in this dwarf galaxy, probability alone dictates that there must be millions of them. The view from the surface of such a planet would be truly amazing, with the Milky Way dominating the night sky alongside the Large Magellanic Cloud, the largest satellite galaxy, which is even closer to home.
#8. Titan
A view of Saturn as seen from the surface of Titan, the only moon known to have a dense atmosphere.
Titan is Saturn’s largest moon and, it is, without a doubt, one of the most unusual worlds in our solar system. It’s the only moon with more than a trace atmosphere but, even more impressively, it is unique in that it has lakes, seas, rivers and rain. There’s one huge difference, however; it’s frigid surface temperature of −179 °C precludes the existence of water, so in place of water is liquid methane. Combine that with the orange skies and spectacular view of the ringed world overlooking the land, and you’ve got a truly alien sky that is also, in some way, incredibly familiar.
#9. Rogue Worlds
An artist’s impression of a lonely planet floating in interstellar space.
Imagine a world that doesn’t have a sun at all, not even a stellar remnant such as a pulsar or white dwarf. Instead, it floats lonely through interstellar space where it’s always night. These are rogue planets ejected from their original solar systems by an event such as a supernova. It sounds like the goth’s ultimate fantasy, but these planets may number in the billions in the Milky Way galaxy alone. Nonetheless, such a world could be home to moons with subsurface oceans like those on Europa on Enceladus, kept liquid by tidal heating from an enormous gas giant planet.
#10. Venus
One day, humans may live on Venus is huge floating aerostat habitats comfortably far above the infernal surface.
Lastly, we have the most dreadful environment in the solar system. Or is it? While Venus’s hellish surface is under extreme pressures and scorching temperatures, the planet’s clouds present one of the most hospitable environments in our solar system. Some 34 miles (55 km) above the surface, the Venusian atmosphere sports a comparable air pressure and temperature to those found on Earth. Provided there is access to oxygen and protection from the sulphuric acid rain, we may one day be able to colonise the clouds of Venus with enormous floating aerostat cities.
