Unveiling the Mysteries: The Unsung Heroes of Our Solar System

Our solar system is a great big messy place full of planets and dwarf planets (yes, there’s a difference) and asteroids and comets. But it’s not just the planets that hold wonders: there are a whole slew of minor bodies that play an important role in exploring the origins and evolution of the solar system. In this series, we’ll take a tour of these quirky outliers, looking at their story through the lens of our understanding of how the solar system formed and evolved over time.

The Enigmatic World of Arrokoth

Arrokoth, one of the oldest planetesimals in the Kuiper Belt, likely formed around 4 to 4.5 billion years ago, during the solar system’s infancy. It’s a little icy world that, until January 2019, remained hidden from view. After the New Horizons mission revealed that Arrokoth had two distinct sides – one light and one dark – and was actually a double-lobed planetesimal, scientists started to uncover how these pieces of ice and rock added up to the formation of our solar system.

Chariklo's Icy RINGS: A Marvel of the Cosmos

Chariklo itself is the largest centaur — comet-asteroid hybrids that circle the Sun, my favourite celestial oddballs — but even in that company Chariklo stands apart because it is the first known rocky body in the solar system to sport no fewer than two rarefied ice rings. In fact, the very existence of Chariklo’s rings pushes the boundaries of what we know about ring-forming conditions, and represents a tantalising glimpse into the hidden intricacies of the cosmos.

The Mystery and Magic of Mimas

The ‘Death Star’: Mimas, the smallest of Saturn’s moons, with its huge Herschel Crater, nicknamed the ‘Death Star’ for it resemblance to the iconic Star Wars space station. This picture from the Voyager 1 spacecraft shows Mimas (240km x 190km) compared to our Moon (3,470km). Courtesy NASAWhat is so intriguing about this nickname for Mimas? Well, sure it might resemble the iconic Star Wars space station, but it has more going on than a Death Star-like appearance. If you dig right down to the crust, you will find Mimas is actually made from ice. This might seem out of place orbiting so close to Saturn. But there’s more. Even more strange than its composition, Mimas has an extremely eccentric orbit. Its eccentricity is 0.311, which is more than twice the eccentricity of our nearest planetary neighbour, Venus (0.00677). How can this be? Orbiting so close to Saturn, why is Mimas so eccentric? This is what I set out to try to explain.

Ceres: A Dwarf Planet with Big Secrets

The first, Ceres, which sits in the asteroid belt between Mars and Jupiter, pushes up against certain boundaries between asteroid and dwarf planet. As the largest object between Earth and Jupiter, it’s the only dwarf planet in the inner solar system. Given its copious reservoirs of water ice, it’s also a key spot in the search for any life that might exist beyond our world.

Dinkinesh: A Testament to Cosmic Wonders

Selam, an intricate contact binary system concealed within the tiny asteroid known as Dinkinesh, located in the asteroid belt’s main asteroid belt. Photo courtesy of Danielle Moser/Adobe StockWithin its confines, Dinkinesh also harbours two smaller objects that orbit each other in a contact binary system – a recent discovery that’s not only intriguing but that also pushes our understanding of the cosmos’s evolution and variety to new levels.

The Quasi-Moons of Earth

Seven of those quasi-moons inhabit our Sun’s orbital plane with Earth, in our own solar system. Of the seven co-orbital asteroids, Kamo’oalewa contains one of the most stable orbits, and could conceivably orbit with Earth around the Sun for the next several million years. Their orbits reveal the gravitational ballet of the solar system.

A Universe of Twins: The Binary Asteroids

Binary asteroids are a reminder that, sometimes, twins have taken over the cosmos. The 2017 YE5 is one such example, with two nearly identical rocky bodies orbiting each other. Such objects emphasise the diversity of asteroid quintets, pitting up to five interlocking bodies against one another, and push astronomers to re-evaluate formation theories – as well as discover new configurations of gravity.

Io: Jupiter's Volatile Offspring

Io, Jupiter’s innermost of the Galilean moons, shows it’s furious face as the most active volcanic body in the solar system. Gravitational tugs-of-war with Jupiter stretch Io to its breaking point, and are the cause of its volcanic rage. The violent moon is a window to the powerful forces at work in the solar system.

Haumea: The Fast-Spinning Dwarf Planet

Haumea lies in the Kuiper Belt, where it spins at breakneck speed in an elongated shape. It is an icy dwarf planet encrusted with crystallised water ice and has two moons. It shows how processes carve a path in the outer solar system.

Comet 67P/Churyumov-Gerasimenko: A Celestial Time Capsule

The single-minded devotion and consistent results made possible technological wonders. In 2014, the Philae lander from ESA’s Rosetta mission became the first spacecraft to land on a comet – in this case, Comet 67P/Churyumov-Gerasimenko – revealing this celestial vagabond’s composition and habitat in detail. Trapped in time like a bottle inering, the delivery vehicle of 67P’s slushy solar-system-forming ice-rock nucleus bears witness to the dawn of the solar system.

UNDERSTANDING THE RING PHENOMENON

Rings are not the exclusive prerogative of the giant planets; Chariklo’s icy rings prove that they are processes and structures that extend beyond size and material. Both in how they form and why these rings stick around, nature leaves us baffled – and in awe. The rings of the solar system are a testament to the power and beauty of celestial art, to the mysteries that surround even our own neighbourhood of the universe.

Now these unsung heroes – icy worlds, ringed centaurs, flaming moons, and elusive comets – call on us to push the boundaries of our knowledge of space within our own solar system. As each of these objects introduces a new narrative or reveals a new story, our universe grows, enabling us to contemplate what lies beyond our home planet.