Our solar system is an undeniably fascinating place, featuring an assortment of celestial oddities and wonders. Between the planets, moons, comets, and asteroids, there’s no shortage of places for us to explore. Slowly but very surely, we’re finding all sorts of incredible—and sometimes unexplainable—phenomena.
Here, we present to you some of the most dramatic and enigmatic places within our home star system.
A version of this story was originally published on June 19, 2020.
Mars’s Olympus Mons, one of the largest volcanoes in the solar system, is all sorts of ridiculous. It measures 374 miles (600 km) in diameter, which is roughly the same size as Arizona. Its summit caldera rises some 15 miles (24 km) above the surrounding Martian plains. Olympus Mons is the product of excessive lava flows, likely the result of lower surface gravity and frequent eruption rates.
During its 2015 flyby of Pluto, NASA’s New Horizons spacecraft captured images of the dwarf planet’s bladed terrain, littered with gigantic shards of methane ice the size of skyscrapers. Astoundingly, the tallest of these structures reach 1,600 feet (500 meters) tall. A similar formation, called penitentes, is seen on Earth at a vastly smaller scale. Planetary scientists theorize that, millions of years ago, methane froze at Pluto’s high elevations and has been slowly evaporating into gas over time, in a rather unique form of erosion. Jupiter’s moon Europa exhibits similar features, the tallest of which measure five stories high.
Saturn’s moon Titan is arguably the most alien place in the solar system, with its thick atmosphere, hydrocarbon seas, giant dust storms, ice volcanoes, and precipitation in the form of raining methane and ethane. In 2013, NASA’s Cassini spacecraft spotted a 100-square-mile (260 square km) island-like geological formation in Ligeia Mare, one of Titan’s largest seas. Previous scans showed no signs of this feature, and it proceeded to disappear over the next several months. And then it appeared again.
Scientists aren’t entirely sure what it is, citing such possibilities as waves, bubbles, floating solids, and suspended solids (like silt in a terrestrial delta). Also, because Titan was transitioning from spring into summer at the time of the observations, scientists believe the phenomenon is tied to the change of seasons. Like I said, Titan is a very alien place.
Verona Rupes is a cliff on Uranus’s moon Miranda, and at 12.4 miles deep (20 km), it’s the tallest sheer cliff in the solar system. For perspective, Verona Rupes is 10 times deeper than the Grand Canyon. Its edge seems like an ominous place to stand and gaze at the wonder that is Miranda, but here’s the funny thing—you could probably survive a leap off this colossal structure, thanks to the paltry gravity on this tiny moon, which measures just 292 miles (470 km) in diameter. According to NASA, a free fall from top to bottom should take about 12 minutes, so you better bring something to read for the trip down. As to how this structure formed, scientists suspect a large impact or tectonic forces.
Saturn has around 60 moons, some of which are located either inside or next to its majestic ring system. Five of these ring moons, as they’re called, are exceptionally weird in terms of their physical appearance, featuring equatorial bulges. Some bulges are pronounced and amorphous, while others are more skirt-like in how they’re wrapped around the moons.
Recent research suggests these moons—none of which is wider than 12 miles (20 km) across—formed from the same giant impact that spawned Saturn’s rings.
“The moons are giant shards left over from the impact,” Bonnie Buratti, an astronomer from NASA’s Jet Propulsion Laboratory and the California Institute of Technology, told Gizmodo in March of 2019. “The ‘skirts’ around their equators are particles from the rings that continue to accrete. The way the moons scoop out particles in their path could be a smaller example of how planets form from smaller particles.”
After New Horizons flew past Pluto in 2015, mission controllers at NASA steered the spacecraft toward a mysterious Kuiper Belt object called 2014 MU69. This distant object is located around 44 AU from the Sun, or around 4 billion miles from Earth (6.5 billion km), making it the farthest object ever visited by a probe.
We knew New Horizons would find something exotic, but nothing prepared us for the images it sent back soon after its brief encounter on New Year’s Day 2019. Arrokoth, as the object is now named, looks like a two-lobed snowman. Astronomers call it a contact binary, in which two distinct objects have fused together to form a singular structure. It’s very cool, if not a bit spooky.
Located on Comet 67P/Churyumov-Gerasimenko’s large lobe, Imhotep is a remarkably diverse region covering about 200 acres. It is one of the “most geologically diverse regions” observed by the Rosetta probe, according to the ESA, and an excellent place for studying the comet and how it formed.
In addition to an unusually flat swatch of real estate filled with fine-grained materials, Imhotep features many boulders (2,207 to be exact), rocky terrains, basins in which rocks and boulders have accumulated, fractured terraces indicative of internal layering, bright patches pointing to the presence of ice, and mysterious roundish features not seen elsewhere on the object. Comets, as Imhotep demonstrates, are far from boring.
On its own, Io is easily one of the most mind-blowing places known to astronomers. In orbit around Jupiter, Io is the most volcanically active object in the solar system, featuring lakes of molten silicate lava on the surface. Io’s extreme volcanic nature is due to gravitational forces exerted by Jupiter and two neighboring moons, Europa and Ganymede.
Lots of volcanoes exist on Io, but Loki takes the cake, accounting for 15 percent of the moon’s total heat expenditure. What’s more, this 124-mile-wide (200 km) volcano is a periodic volcano, meaning its eruptions tend to follow a distinct pattern. Since 2013, Loki has been erupting at roughly 475-day intervals, with eruptions lasting for roughly 160 days.
Behold the largest skating rink in the solar system: Korolev Crater on Mars. Located in the northern lowlands of the Red Planet, the crater measures 51 miles (82 km) in diameter. The ice within this crater is a permanent feature, which, wow. Who’s up for the most epic game of hockey in the history of the solar system?
Titan has a large equatorial desert called the Shangri-la Land Sea, and it features a rather impressive network of sand dunes. These dunes extend across an area measuring over 3.9 million square miles (10 million square km), with some individual dunes reaching as tall as 330 feet (100 meters). Sand dunes on Earth are composed primarily of silicates, but Titan’s dunes are made from organic materials bombarded into existence by the Sun’s cosmic rays, according to recent research.
Venus’s most terrifying feature—its atmosphere—is also its most fascinating. Clouds located in the upper atmosphere race across the planet at speeds reaching 224 miles per hour (360 km), blowing from east to west (opposite to how we do it here on Earth). Hurricane-strength winds perpetually blow across the entire globe, though at altitude. Oh, and these clouds are filled with sulfuric acid that rains down upon the planet’s surface, hot enough to melt lead. To add insult to injury, the planet has electric winds that stripped the planet of its atmospheric water. Venus also features one of the most impressive atmospheric structures in the solar system—a bow-like weather feature that stretches for nearly 6,200 miles (10,000 km) across the planet.
We tend to associate Saturn with circles, from its monumental rings to the yellow and gold bands in its upper atmosphere. That’s why the hexagon-shaped storm at the planet’s north pole seems so jarring. It’s just so... unnatural. The storm, which measures some 19,000 miles (30,000 km) across, is caused by alternating flows and high-latitude zonal jets, according to new research. It’s undeniably weird, but yet another striking feature of the solar system’s most striking planet.
Valles Marineris is the largest canyon in the solar system, stretching for a whopping 370 miles (600 kilometers). At its deepest, the canyon reaches a depth of 5 miles (8 km). The Grand Canyon in Arizona is a bit longer, but it’s only 1.1 miles (1.8 km) deep. Keep in mind, however, that the diameter of Mars is only slightly more than half of Earth’s diameter. Fair to say, if Mars had a vibrant tourist industry, Valles Marineris would be a must-see.
Our solar system is home to some really amazing and bizarre places, but absolutely nothing compares to Earth. Located in a stable orbit within the habitable zone, our home planet features a highly protective magnetic field, an oxygen-rich atmosphere, copious amounts of liquid water, plate tectonic activity, lots of terrestrial surfaces, regularly changing seasons, and of course, life.